Controllable Multicompartmental Capsules with Distinct Cores and

Subscriber access provided by NEW YORK UNIV

Article

Controllable Multi-Compartmental Capsules with Distinct Cores and Shells for Synergistic Release Fan He, Wei Wang, Xiao-Heng He, Xiu-Lan Yang, Ming Li, Rui Xie, Xiao-Jie Ju, Zhuang Liu, and Liang-Yin Chu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b01278 • Publication Date (Web): 15 Mar 2016 Downloaded from http://pubs.acs.org on March 18, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Controllable Multi-Compartmental Capsules with Distinct Cores and Shells for Synergistic Release Fan He,† Wei Wang,*,† Xiao-Heng He,† Xiu-Lan Yang,† Ming Li,† Rui Xie,† Xiao-Jie Ju,† Zhuang Liu,† and Liang-Yin Chu*,†,‡,§

†

School of Chemical Engineering, Sichuan University, No. 24, Southern 1 Section, Yihuan Road,

Chengdu, Sichuan 610065, P. R. China ‡

State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan

610065, P. R. China §

Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing,

Jiangsu 211816, P. R. China

ACS Paragon Plus Environment

1


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 47

ABSTRACT: A facile and flexible approach is developed for controllable fabrication of novel multiple-compartmental calcium alginate capsules from all-aqueous droplet templates with combined co-extrusion minifluidic devices for isolated co-encapsulation and synergistic release of diverse incompatible components.

The multi-compartmental

capsules exhibit distinct

compartments, each of which is covered by a distinct part of a heterogeneous shell. The volume and number of multiple compartments can be well-controlled by adjusting flow rates and device numbers for isolated and optimized encapsulation of different components; while the composition of different part of the heterogeneous shell can be individually tailored by changing the composition of droplet template for flexibly tuning the release behavior of each component. Two combined devices are first used to fabricate dual-compartmental capsules, and then scaled up to fabricate more complex triple-compartmental capsules for co-encapsulation.

The

synergistic release properties are demonstrated by using dual-compartmental capsules which contain one-half shell with constant release rate and the other half shell with temperaturedependent release rate. Such a heterogeneous shell provides more flexibilities for synergistic release with controllable release sequence and release rates to achieve advanced and optimized synergistic efficacy. The multi-compartmental capsules show high potential for applications such as drug co-delivery, confined reactions, enzyme immobilizations, and cell cultures. KEYWORDS:

Multi-compartmental capsules; Distinct shells; Calcium alginate; Co-

encapsulation; Synergistic release


2

Page 3 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


INTRODUCTION Capsules are widely used as encapsulation systems for protection of active species,1-3 immobilization of cells and enzymes,4-9 controlled release of drugs,10-12 and confined microreaction of chemicals.13-15 Multi-compartmental capsules are highly functional carriers, as they can provide separate compartments for independent co-encapsulation of diverse incompatible actives in one single capsule, without cross-contamination.16-18

Moreover, by

introducing functional materials into the capsule shell, they enable on-demand synergistic release of different components,19,20 and allow reaction of multiple encapsulated reactants upon triggering.21,22 Multi-compartmental capsules containing controllable distinct core compartments and heterogeneous shell with distinct parts covering different compartments exhibit a higher flexibility for controlled release of different encapsulants. Control of the volume and number of core compartments allows accurate manipulation of the quantities and the types of encapsulants for flexible and controllable co-encapsulation. Control of the permeability of different shell parts facilitates independent adjustment and flexible combination of the release behavior of the encapsulant in each relevant compartment for more versatile release, such as sequential release and synergistic release. Therefore, development of such multi-compartmental capsules with controllable distinct core compartments and heterogeneous shell is highly desired for applications such as co-encapsulation and controlled release in biomedical or biological fields. Typically, multi-compartmental capsules can be developed by several strategies that employ templates for creating the compartments. Polyelectrolyte dual-compartmental capsules with capsule-in-capsule structures can be fabricated by a two-step Layer-by-Layer deposition process on sacrificial CaCO3 particle templates, followed with template removal, for spatially confined enzymatic micro-reactions.23,24 However, such techniques require harsh solvent for template


3


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 47

removal and troublesome multi-step process for fabrication. Utilization of liquid droplets as compartment templates allows direct use of the droplets as liquid compartments for encapsulation, or easy removal of the droplets by mild washing. Capsules with distinct internal compartments that act as chemical microreactors can be fabricated by encapsulating multiple water droplets with an assembled amphiphilic polymer bilayer in oil and then transferring the droplets into water phase based on gravity-mediated settlement.25,26 The contents and number of the compartments can be well controlled, but the fabrication process is time-consuming and lowyielding.

Alternatively, by using core-shell droplets from compound-fluidic electrospray as

templates, multi-compartmental titania capsules can be effectively fabricated for encapsulation and release of actives.27 However, it is worth noting that, precise control of the structures of the capsules and the compartments remains difficult for the above-mentioned multi-compartmental capsules.

With fantastic manipulation of droplets,28-31 emulsions prepared by microfluidic

techniques can be used as excellent templates for fabricating multi-compartmental capsules.1,32-36 Typically, capsules with concentric dual-compartments can be fabricated by using core-shell double emulsions as templates. The two compartments can be separately used for encapsulation of hydrophilic and hydrophobic components without cross-contamination for synergistic release.35 Moreover, more complex capsules with concentric multiple-compartments can be created by incorporating smaller capsules with single or dual compartments in the inner droplets of the double emulsions for programmed release of multiple components.34 By using double emulsions with multiple inner droplets, capsules with multiple parallelly-located compartments covered by a shell can be fabricated.19,32,33,37 The accurate control of the size, number and type of the emulsion drops provided by microfluidics enables precise manipulation of the structures of the capsules and compartments and effective optimization of the encapsulation conditions for co-


4

Page 5 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


delivery of multiple distinct components.

Although these capsules can provide diverse

compartments for flexible encapsulation of versatile components, their shells that cover these compartments are usually with homogeneous structures. Thus the release behavior of each component can not be individually tailored, which restricts the use of these capsules for more flexible applications in biomedical, biological or chemical fields, such as controlled release and confined reaction.

Recently, capsules with multiple distinct compartments covered by their own

shells are developed by using microfluidic double emulsions with distinct inner cores contained in a Janus outer droplet.36 However, the fabrication process involves organic solvents and UV irradiation, which limit the use of the capsules for encapsulating sensitive biomolecules or cells for biomedical applications. Therefore, development

of

a

simple and green technique

for

controllable fabrication of multi-compartmental capsules with distinct core compartments and a heterogeneous shell is quite essential and important. Here we report on a facile, flexible and green strategy for controllable fabrication of multicompartmental

capsules

with distinct compartments covered by a heterogeneous shell for co-

encapsulation and synergistic release. The volume and number of the multiple compartments can be well-controlled by adjustment of flow rates and device numbers, while the composition of different part of the heterogeneous shell can be individually tailored by changing the composition of the droplet template.

We first demonstrate this by fabricating dual-

compartmental capsules, and then scaling up to fabricate more complex triple-compartmental capsules. Calcium alginate (Ca-Alg), which is widely used for cell culture and enzyme immobilization due to its biocompatibility and mild fabrication process,38-46 is employed as shell materials to construct the capsule.

Up to now, multi-compartmental Ca-Alg hydrogel spheres

with heterogeneous network fragments have been fabricated by a centrifuge-based droplet


5


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 47

formation method,40 or an electro-millifluidic method,41-43 for bioengineering applications such as encapsulation of enzymes and cells. Compared to Ca-Alg hydrogel spheres, Ca-Alg capsules with hollow compartments provide more capacity for encapsulation, but controllable fabrication of multi-compartments in the capsules still remains challenging. Therefore, we employ the CaAlg as shell materials to demonstrate the power of our strategy for controllable fabrication of multi-compartmental capsules. Two water-in-water (W/W) droplets, with outer layer containing sodium alginate (Na-Alg) for constructing the shell and inner aqueous cores for encapsulating actives, are generated by two co-extrusion minifluidic devices for capsule fabrication. The two droplets are then coalesced by a stainless steel needle fixed below the devices to form a Janus ϴshaped droplet as templates for fabricating the capsules via

crosslinking

in

Ca2+-containing

solution. Each composition of the inner and outer droplets in the two W/W droplets can be individually manipulated, thus dual-compartment capsules with two separate compartments, each of which is covered by its own half of a Janus shell can be fabricated. Scale-up of the capsule structure can be achieved by simply combining three minifluidic devices for fabricating triplecompartmental capsules. The co-encapsulation of diverse components is demonstrated by using the dual- and triple-compartmental capsules for separately encapsulating distinct components in each of their compartments. Moreover, the synergistic release is demonstrated by using dualcompartmental capsules with one half of the Janus shell embedded with thermo-responsive nanogels to achieve temperature-dependent shell permeability for controlled release. Thus, encapsulants in their two compartments can show two different release behaviors, one of which with constant release rate and the other with temperature-dependent release rate, for flexible synergistic release, indicating tunable release sequence and rates. The multi-compartmental


6

Page 7 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


capsules developed in this work are highly potential for applications in various fields such as drug co-delivery, confined reaction, enzyme immobilization, and cell culture.

EXPERIMENTAL SECTION Materials.

Rhodamine B labeled dextran (TRITC-dextran) (Mw=20 kDa), fluorescein

isothiocynate labeled dextran (FITC-dextran) (Mw=20 kDa and 150 kDa), folic acid and Nisopropylacrylamide (NIPAM) are purchased from Sigma-Aldrich. Disperse Red and Disperse Blue are purchased from Jialong Dyeing. N,N-methylenebisacrylamide (MBA), ammonium persulfate (APS), sodium alginate (Na-Alg), sodium carboxymethylcellulose (CMC) and calcium nitrate (Ca(NO3)2) are all of analytical grade and purchased from Chengdu Kelong Chemical Reagents. Pure water produced from water purification system (Elix®10, Millipore) is used throughout the experiments. Fabrication of Dual-Compartmental Ca-Alg Capsules. A co-extrusion minifluidic capillary device used for fabricating W/W droplets (Figure 1a) is fabricated according to our previous work.47 Briefly, a square tube, with outer dimension of 1.4 mm, is inserted into a cylindrical capillary tube with inner diameter of 2.0 mm to construct a co-flow geometry. The outlet of the square tube is treated to obtain a cylindrical cone. Illustrations A–A and B–B in Figure 1a are cross-section images of the minifluidic device in relevant positions. By separately injecting the inner fluid (IF) and outer fluid (OF) into the square tube and cylindrical tube via pumps (LSP012A, Baoding Longer Precision Pump), W/W droplets can be formed at the outlet of the cylindrical tube. To prepare dual-compartmental Ca-Alg capsules, two co-extrusion minifluidic devices are combined and placed nearly vertically (Figure 1b) to generate two different W/W droplets.


7


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 47

Typically, aqueous solutions containing 1% (w/v) CMC are used as the inner fluid 1 (IF1) and inner fluid 2 (IF2) to construct the core compartment of the W/W droplets; while aqueous solutions containing 1.5% (w/v) Na-Alg are used as the outer fluid 1 (OF1) and outer fluid 2 (OF2) to construct the shell compartment. The viscosities of the 1% (w/v) CMC solution and 1.5% (w/v) Na-Alg solution are measured by viscosimeter (DV2TLV-CP, Brookflied) at 25 ºC. The flow rates of the inner fluids and outer fluids for droplet generation are 20 mL h-1 and 15 mL h-1 respectively. To fabricate dual-compartmental capsules with distinct core compartments, 0.2% (w/v) folic acid is added in IF2; while, to fabricate dual-compartmental capsules with Janus shell, 0.1% (w/v) Disperse Red and Disperse Blue are respectively added in OF1 and OF2. After droplet generation, the two W/W droplets simultaneously fall across a stainless steel needle horizontally arranged between them, which triggers their coalescence to form a Janus ϴ-shaped droplet. The height difference between the needle and the outlet of the cylindrical tubes is 6 mm. Then, the Janus ϴ-shaped droplet falls into an aqueous solution of 10% (w/v) Ca(NO3)2, where the Ca2+ crosslinks the alginate in the outer layer of Janus ϴ-shaped droplet to form the dualcompartmental capsule. For functionalization of the capsules with magnetic-responsive property, 0.5% (w/v) magnetic nanoparticles (MNPs) that are prepared according to our previous study,48 are added in the 1.0% (w/v) CMC solution as IF2 to construct a MNPs-containing compartment. For fabrication of dual-compartmental capsules, with one compartment protected by a Ca-Alg shell embedded with poly(N-isopropylacrylamide) (PNIPAM) nanogels as thermo-responsive microgates for controlled release, 1% (w/v) PNIPAM nanogels are added in the 1.5% (w/v) NaAlg solution as OF2. The monodisperse PNIPAM nanogels are synthesized by precipitation


8

Page 9 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


polymerization,49 and their morphology are characterized by field-emission scanning electron microscope (FESEM, JSM-7500, JEOL). Morphological Characterization of Dual-Compartmental Capsules.

The formation

process of the dual-compartmental capsule is monitored by high-speed digital camera (pco edge 4.2, PCO) through a macro lens (AF-S VR Miro-Nikkor 105 mm f/2.8 G IF-ED, Nikon). The morphologies of dual-compartmental capsules are characterized by digital camera (PEN Lite EPL5, Olympus), fluorescence microscope (SZX16, Olympus) and confocal laser scanning microscope (CLSM) (SP5 II, Leica). To differentiate the distinct cores and Janus shell under fluorescent field, 8 µmol L-1 FITC-dextran (Mw=150 kDa) is added in IF2 or OF2 respectively. Magnetic-Responsive Property of Dual-Compartmental Capsules. To test the magneticguided rotational motion, the dual-compartmental capsule with magnetic functionalization is used as sample and placed in a water-containing holder. The holder is placed on a magnetic stirrer with a constant rotation speed. To test the magnetic-guided translational movement, dualcompartmental capsules with magnetic functionalization are placed in a water-containing holder, and guided by a cylinder-shaped magnet (Size: Φ 20 mm × 8 mm) with surface magnetic intensity of 2.1 T. Synergistic Release Behavior of Dual-Compartmental Ca-Alg Capsules. To investigate the synergistic release behaviors of two solutes through the different halves of the PNIPAMnanogel-embedded Janus shell, 6 µmol L-1 TRITC-dextran (Mw=20 kDa) and FITC-dextran (Mw=20 kDa) are used as model solutes and added in the 1% (w/v) CMC solution as IF1 and IF2, respectively. First,

the thermo-responsive hydrodynamic diameters of the PNIPAM nanogels in pure water

are measured by dynamic light scattering (DLS) (Zetasizer Nano-ZEN3690, Malvern) at


9


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 47

temperatures ranging from 20 ºC to 47 ºC. Before each measurement, the dispersion of PNIPAM nanogels is equilibrated at each predetermined temperature for 20 min. Next, the temperature-dependent diffusional permeabilities of the Janus shells for TRITCdextran and FITC-dextran are investigated by fluorescent photometer (RF5301PC, Shimadzu). After crosslinked in Ca(NO3)2 solution for 1 min, the resultant capsules, with each compartment containing a distinct solute, are transferred into 50 mL pure water at 25 ºC or 40 ºC for studying the synergistic release behaviors. Under conditions of continual shaking, the time-dependent concentrations of TRITC-dextran and FITC-dextran in the surrounding medium are measured by the fluorescent photometer. The excitation wavelengths of TRITC-dextran and FITC-dextran are 553 and 488 nm respectively, while the emission wavelengths are 576 and 520 nm respectively. Scale-up of the Devices for Fabricating Triple-Compartmental Ca-Alg Capsules. To fabricate triple-compartmental capsules, three co-extrusion minifluidic devices are combined for generation of three W/W droplets. Meanwhile, a stainless steel needle is horizontally fixed below the outlet of the three co-extrusion minifluidic devices for coalescing the three W/W droplets. The third IF is 1% (w/v) CMC solution with 0.1% (w/v) Disperse Red, and all the outer fluids are 1.5% (w/v) Na-Alg solutions. The flow rates of the inner fluids and outer fluids are 20 mL h-1 and 15 mL h-1 respectively.

RESULTS AND DISCUSSION Controllable Fabrication of Dual-Compartmental Ca-Alg Capsules. Two co-extrusion minifluidic devices are combined for controllable fabrication of the dual-compartmental Ca-Alg capsules (Figure 1). The co-extrusion minifluidic device is made by assembling of a square tube inside a cylindrical capillary tube to construct a co-flow geometry. Two fluids, with one flowing


10

Page 11 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


in the inner square tube and the other in the interstice between the square tube and cylindrical capillary tube, can be broken into core-shell droplets at the outlet of the device (Figure 1a). For fabrication of capsules with water-containing core and Ca-Alg shell, 1% (w/v) CMC solution and 1.5% (w/v) Na-Alg solution, with viscosities of 398.5 ± 9.3 mPa s and 779.5 ± 18.6 mPa s, are respectively used as IF and OF for generating W/W droplets. The high viscosities of IF and OF protect the W/W droplets against fast mixing, then the W/W droplets can be collected in Ca2+containing solution and effectively converted into core-shell capsules via rapid crosslinking between Ca2+ and alginate.47,50,51 By combining two co-extrusion minifluidic devices (Figure 1b), two W/W droplets can be simultaneously formed at the device outlets (Figure 1c). The angles of the device inclination are 4º, and the distance between the centers of the outlets of two devices is 4.4 mm. A horizontally arranged stainless steel needle is used to trigger the coalescence of the two W/W droplets during their falling process; this leads to formation of a Janus ϴ-shaped droplet (Figure 1d, and Movie S1). Due to the highly-viscous IF and OF, mix of the two core solutions and two shell solutions in the Janus ϴ-shaped droplet can be avoided. Subsequently, the Janus ϴ-shaped droplet falls into the Ca2+-containing solution, in which the Ca2+ crosslinks with alginate very rapidly to form Ca-Alg capsule with dual-compartments (Figure 1e). The formation mechanism of the Ca-Alg capsules is based on the fast crosslinking between Na-Alg and Ca2+ ions. First, during the falling of the shell

Janus

ϴ-shaped droplets in air, the alginate in their

solutions remains uncrosslinked, due to the absence of Ca2+ (Figure

1f). After the droplets

drop into the aqueous solution containing high concentration of Ca2+, the Ca2+ diffuse into the shell

solutions of the Janus

ϴ-shaped droplets, and then rapidly crosslink the alginate for

constructing the Ca-Alg shells (Figure

1g).

Since alginates are anionic polysaccharides

composing of 1,4-linked β-D-mannuronic acid and α-L-guluronic acid, their crosslinking can be


11


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 47

achieved by exchange of Na+ from the α-L-guluronic acid with Ca2+ for forming an egg-box structure with different alginate chains (Figure 1h).52 The egg-box structure restricts the free motion of the alginate chains, which results in the sol-gel transformation of alginate for constructing the Ca-Alg shell. In general conditions, Ca-Alg shell of the dual-compartmental capsules exhibits a desirable chemical stability and a slow degradation rate. Although the degradation of Ca-Alg networks can be accelerated in the presence of phosphate buffer, high pH solution, or chelating agent such as citrate or Na+ with high concentration, the dualcompartmental Ca-Alg capsules can show good stability for at least several months without the above-mentioned conditions.52 It is worth noting that, the use of stainless steel needle is necessary for the formation of Janus ϴ-shaped droplet for fabrication of dual-compartmental capsules. Without the needle,

the

coalescence of droplets from the two devices can also be achieved by decreasing the distance between the two outlets; however, the coalesced droplet adheres to both outlet tips of the two devices, leading to continuous mixing of IF1, IF2, OF1, and OF2 for several seconds. Thus, although the coalesced droplet can fall with increasing volume, the internal of the falling droplets are totally mixed, resulting in no ϴ-shaped structures. Therefore, for successful fabrication of the dual-compartment capsules, the stainless

steel

needle is required to coalesce two separately-

formed W/W droplets. This restricts the solution mixing in the falling droplets within ~1 s before they drop into the Ca2+-containing solution for crosslinking, ensuring the continuous fabrication of dual-compartmental capsules. A high-speed camera is used to monitor the formation process of the dual-compartmental capsules (Figure 2a). First, the Janus ϴ-shaped droplet drops into the Ca2+-containing solution, and its shape is deformed due to the impact of the air/water interface. During the falling process


12

Page 13 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


and the crosslinking process, mix between the shell layer and the core compartment, and mix between the two core compartments, are effectively avoided due to the high viscosities of the core solutions and the shell solutions. This is important for fabricating capsules with dual compartments and Janus shell from these Janus ϴ-shaped droplets. It should be noted that, the addition of CMC in aqueous solution as IF is necessary to maintain the structure of the Janus ϴshaped droplet, otherwise surfactant and specific preparation conditions are required for capsule fabrication.53 After entering into the Ca2+-containing solution, the aqueous shell layer of Janus ϴ-shaped droplet is converted into Ca-Alg hydrogel shell within dozens of milliseconds, due to the fast crosslinking between Ca2+ and alginate. Thus, capsules with dual compartments and Janus Ca-Alg shell can be obtained. The effect of the falling height of the coalesced droplet (H), defined as the distance between the horizontally fixed stainless steel needle and the surface of the Ca2+-containing solution, on the structure of the resultant dual-compartmental capsules is investigated (Figure 2b). For H values varied in the range from 0.7 cm to 34 cm, all the resultant dual-compartmental capsules show intact ϴ-shaped structures with two distinct core compartments without crosscontamination. At H values lower than 0.7 cm, the core solutions and shell solutions touch the surface of the Ca2+-containing solution and spread out before complete coalescence of the two W/W droplets, thus capsules can not be fabricated. At H values higher than 9.4 cm, dualcompartmental capsules can be formed, but with non-uniform compartments, due to the strong impact of the air/water interface on the Janus ϴ-shaped droplet. The results show that our technique is a robust approach for the effective fabrication of dual-compartmental capsules at a wide range of falling heights.


13


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 47

Dual-Compartmental Capsules with Controllable Distinct Cores.

The resultant dual-

compartmental capsules show good shape and high uniformity (Figure 3a). The individual liquid cores of these capsules can serve as separate compartments for co-encapsulation of distinct components, which allow the encapsulated components well isolated from each other. Moreover, since the Janus ϴ-shaped droplet templates are derived from the two W/W droplets, change of relevant flow rates enables accurate and separate manipulation of the structures of the two W/W droplets for tailoring the structure of Janus ϴ-shaped droplet.

This allows excellent and

individual control of the volumes of core compartments and shell halves for flexible coencapsulation. We demonstrate the excellent controllability by fixing the flow rates of IF1 (QIF1) and OF1 (QOF1) respectively at 20 mL h-1 and 15 mL h-1 to keep QIF1/(QIF1+QOF1) at 4/7, and changing the flow rates of IF2 (QIF2) and OF2 (QOF2) to adjust the capsule structure (Figure 3b). For the changes of QIF2 and QOF2, their sum (QIF2+QOF2) is kept constant as that of (QIF1+QOF1). This is necessary to synchronize the falling frequencies of W/W droplets from both devices, because their falling occurs with increasing their volume. Such a setup of flow rate ensures the continuous production of Janus ϴ-shaped droplets on the stainless steel needle for capsule fabrication. When QIF2/(QIF2+QOF2) is 4/7, the resultant capsules exhibit symmetrical ϴ-shaped structures, with the volume ratio of the two hemispherical core compartments equal to 1:1 (VIF1/VIF2=1).

With decreasing the value of QIF2/(QIF2+QOF2), the yellow core compartment

becomes smaller and the relevant shell half becomes thicker; while the transparent core compartment and its shell half remain unchanged, showing an increased VIF1/VIF2.

When

QIF2/(QIF2+QOF2) decreases to 1/9, the resultant dual-compartmental capsules show an unsymmetrical ϴ-shaped morphology, but still with two distinct core compartments enclosed by a Janus hydrogel shell without cross-contamination. Therefore, through the flexible adjustment


14

Page 15 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


of flow rates, the structure of the capsules and the stoichiometric ratio of the encapsulated components can be well manipulated. The dual-compartment structures are further confirmed by using fluorescence microscope and CLSM for characterizing the capsules with one compartment containing FITC-dextran with green fluorescence (Figure 3c and 3d). As shown in Figure 3d, diffusion of the FITC-dextran to the other compartment is not observed. The separate shell between the two compartments effectively isolates the FITC-dextran in its own compartment for avoiding cross-contamination. Moreover,

the bulge in the center of the separate shell may be caused by alginate chain

contraction and Ca2+ diffusion.54 Specifically, for the ϴ-shaped capsule shell, the center part of the separate shell is the last part that crosslinks with Ca2+, due to the inward Ca2+ diffusion. The shape of the non-crosslinked center part can be changed from flat to curved by the surrounding crosslinked shells, due to the contraction of alginate chains. Such a chain contraction exerts a frictional force on the core solution nearby, resulting in the elongation of the non-crosslinked center part. Thus, after final crosslinking of the elongated center part, a bulge is obtained.54 The dual-compartmental capsules provide a novel and promising system for controllable isolated coencapsulation of diverse incompatible components in single capsules, avoiding their crosscontamination. Magnetic-Responsive

Properties

of

Dual-Compartmental

Capsules.

Magnetic

functionalization of the dual-compartmental capsules by encapsulating MNPs in one of compartments allows remote manipulation of the capsules with external magnetic field. Under a rotational magnetic field, the dual-compartmental capsule with one compartment containing MNPs, which is placed in the water-containing holder, can correspondingly rotate with the rotational magnetic field (Figure 4a, and Movie S2). Under a translational magnetic field, the


15


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 47

capsules can instantly respond to the magnet and move towards it (Figure 4b, and Movie S3). The results indicate that the MNPs-loaded dual-compartmental capsules exhibit excellent magnetic-responsive properties for flexible rotational and translational movements. In addition, since their magnetic-responsive properties mainly depend on the encapsulated MNPs content, further improvement of the magnetic-responsive properties can be obtained by increasing the MNPs content in the corresponding compartment.

Such magnetic-responsive dual-

compartmental capsules may show potential as mini-mixers for local stirring and mixing. Furthermore, for the potential applications as carriers for synergistic release, targeted delivering and recycling can be easily achieved via magnetic-guided manipulation. Dual-Compartmental Capsules with Janus Shell. Our technique that employs the ϴ-shaped droplet with Janus shell solutions as capsule templates allows fabrication of dual-compartmental capsules with distinct cores and a Janus shell. Because the shell solutions can remain un-mixed in the Janus ϴ-shaped droplet, simple addition of functional components in different shell solutions enables facile and individual tailoring of the two halves of the Janus shell for versatile functionalization (Figure 5a1). We first demonstrate this by simply adding different dyes in the two shell solutions. As shown in Figure 5a2 and a3, the dual-compartmental capsules exhibit a Janus shell with different halves, with one halve containing Disperse Red and the other half containing Disperse Blue. Moreover, the CLSM images of the dual-compartmental capsule with one half of the Janus shell containing FITC-dextran further confirm the structure of the Janus shell (Figure 5b and 5c). The green fluorescent molecules only exist in one half of the Janus shell, and the boundary between the distinct shell halves remains clear. The results demonstrate that the dual-compartmental capsules designed in our work exhibit distinct core compartments, with each enclosed by a specific half of the Janus shell.


16

Page 17 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Synergistic Release of Different Encapsulants from Dual-Compartmental Ca-Alg Capsules. The dual-compartmental capsules with a Janus shell provide a higher flexibility for co-encapsulation of each compartment with distinct actives and individual modification of the different halves of Janus shell with distinct permeabilities for more versatile controlled-release applications.

We demonstrate such flexible controlled release properties by using dual-

compartment capsules with two compartments containing distinct actives and two shell halves with different permeabilities for combining two controlled-release behaviors in one single capsule.

Fluorescent TRITC-dextran (Mw=20 kDa) and FITC-dextran (Mw=20 kDa) are

respectively encapsulated in the two core compartments as the model solutes. To achieve Janus shell containing two halves with different permeabilities, monodisperse PNIPAM nanogels, with average diameter of 343 nm in air-dried state (Figure S1), are dispersed in the shell solution for embedding the nanogels in one half of the Janus shell, which covers the core compartment containing FITC-dextran, as the functional gates (Figure 6a).

Figure 6b shows the dual-

compartmental capsule with TRITC-dextran (red fluorescent) and FITC-dextran (green fluorescent) encapsulated in distinct core compartments for synergistic release.

The two

encapsulated solutes are well-isolated in their own compartments without cross-contamination. In addition, since the PNIPAM nanogels can show reversible volume phase transitions when temperature changes across the volume phase transition temperature (VPTT) (~33 ºC) (Figure 6c), they can serve as thermo-responsive microgates in the Ca-Alg hydrogel networks to tune the shell permeability for controlled release. When the environment temperature is 25 ºC, below the VPTT, the nanogels are in swollen state, which occupy most of the diffusion channels in the shell half for closing the gates and decreasing the shell permeability. Thus, the release of FITCdextran molecules through this half of the Janus shell is reduced.


By contrast, when the

17


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 47

environment temperature is 40 ºC, above the VPTT, the nanogels are in shrunken state, with their volume dramatically decreasing to lower than 80% of their original volume at 25 ºC (Figure 6c), which open the gates and increase the permeability of this shell half. Then the FITC-dextran molecules can easily permeate through this shell half for enhanced release. Meanwhile, because the other half of the Janus shell contains no thermo-responsive nanogels, its permeability remains constant. Thus, the release behavior of the TRITC-dextran molecules through this shell half remains nearly unchanged at different temperatures. The kinetic analysis of the release behavior is conducted by first investigating the accumulated release behaviors of TRITC-dextran and FITC-dextran through different shell parts of the dualcompartmental capsules at 25 ºC and 40 ºC respectively (Figure 6d). For FITC-dextran released at 25 ºC, and TRITC-dextran released at both 25 ºC and 40 ºC, the results show similar release behaviors, with respectively 23.9%, 21.4% and 24.9% of the encapsulants released at t=33 min. Compared with the above-mentioned three release cases, the release of FITC-dextran at 40 ºC is much faster due to the open state of the PNIPAM nanogel microgates, with 35.7% of the encapsulants released at t=33 min. Next, the release kinetics is further studied by investigating the diffusional permeability coefficient (P) of the solute across the shell at certain temperature, which is determined by the increase of solute concentration in the surrounding medium with time. The P value is calculated using the following Equation (1), which is derived from the Fick’s first law of diffusion:55,56

P=

⎛ C − Ci ⎞ VsVm ln ⎜ f ⎟ A (Vs + Vm ) t ⎝ Cf − Ct ⎠

(1)

where Ci, Ct, and Cf are the solute concentrations in the surrounding medium at the initial, at time t, and at the final, respectively [mol L-1];

Vm is the total volume of the hemispherical


18

Page 19 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


compartments that contain one kind of solutes in all the capsule samples [L]; Vs is the volume of the surrounding medium [L], A is the total surface area of the hemispherical compartments that contain one kind of solutes in all the capsule samples [m2], and t is the time [s]. The Vm and A can be calculated based on the number of capsule samples and the measured average diameter of the compartments. Cf is the measurable solute concentration in the surrounding medium when the equilibrium of the diffusion is reached. Figure 6e shows the diffusional permeation characteristics of the two solutes across the Janus shell of the dual-compartmental capsules at 25 ºC and 40 ºC. A fitted linear relationship is observed between the ln[(Cf-Ci)/(Cf-Ct)] and t for each case. Especially, the slopes of the two fitted straight lines for TRITC-dextran at 25 ºC and 40 ºC are very close to each other, showing similar release behaviors. The hydrogel networks of the Ca-Alg shell, which covers the TRITCdextran-containing compartment, do not change at both temperatures, indicating a nearly constant shell permeability.

Meanwhile, at 25 ºC, the release behavior of FITC-dextran

encapsulated in the compartment covered with nanogel-embedded Ca-Alg shell is also similar to that of TRITC-dextran. This is due to the swollen state of the PNIPAM nanogels in the Ca-Alg hydrogel networks, which provide the shell with similar permeability as that of the Ca-Alg shell without any nanogels. However, at 40 ºC, because the shrinking of the embedded nanogels leads to increase of the permeability of FITC-dextran across the shell, and thus the slope of the fitted straight line is much higher than those of the other three ones, indicating a much faster diffusion of FITC-dextran through the nanogel-embedded shell. Based on the slopes of these fitted straight lines, the value of P can be calculated by equation (2) as follows:

P=

VsVm K A (Vs + Vm )


(2)

19


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 47

where K is the slope of the fitted straight line of ln[(Cf-Ci)/(Cf-Ct)] versus t. Figure 6f shows the calculated P values of the two model solutes across the Janus shell of the dual-compartmental capsules at 25 ºC and 40 ºC. For the TRITC-dextran diffusing across the Ca-Alg shell without any nanogels, their P values are quite similar at both temperatures (5.30 µm s-1 and 5.50 µm s-1 respectively). For the FITC-dextran diffusing across the nanogel-embedded Ca-Alg shell, the P value (9.27 µm s-1) at 40 ºC is much higher than that (6.03 µm s-1) at 25 ºC. All the results show the excellent performance of the Janus shell for individually controlling the release characteristics of each encapsulant for flexible synergistic release. Triple-Compartmental Ca-Alg Capsules. The combined devices can be further scaled up by incorporating more minifluidic devices for controllable fabrication of capsules with more distinct compartments and heterogeneous shell. We demonstrate this by combining three co-extrusion minifluidic devices for fabrication of Ca-Alg capsules with triple compartments (Figure 7a). A stainless steel needle is also horizontally fixed below the device outlets to trigger the coalescence of the three W/W droplets generated from the three devices. After that, the coalesced droplets, with triple core compartments and shell compartments, fall into the Ca2+-containing solution and then form triple-compartmental capsules. The triple-compartmental capsules show three distinct cores (Figure 7b). Similarly, the shell parts that cover different core compartments can be further tailored into different functions by separately incorporating versatile functional components in the shell solutions for more versatile controlled release of multiple encapsulants.

CONCLUSIONS In summary, a facile and flexible strategy has been developed for controllable fabrication of CaAlg capsules with distinct multiple compartments and heterogeneous shell by advanced co-


20

Page 21 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


extrusion minifluidics for isolated co-encapsulation and synergistic release of diverse incompatible components. The volume of each compartment can be well-controlled by adjusting flow rates for optimizing encapsulation conditions, while the compartment number can be wellmanipulated by changing the device numbers for co-encapsulating more diverse components. The composition of different parts of the heterogeneous shell can be separately tailored by changing the composition of droplet template for flexible combination of different release mechanisms and release behaviors for more flexible synergistic release. We demonstrate this by controllable fabrication of dual- and triple-compartmental capsules for isolated co-encapsulation of different components. By incorporating thermo-responsive nanogels in one half of the Janus shell of the dual-compartmental capsules, we demonstrate their advanced synergistic release which combines a constant release rate for one encapsulant and a temperature-dependent release rate for the other encapsulant.

Such a heterogeneous shell provides more flexibilities for

synergistic release of different incompatible components, with controllable release sequence and release rates to achieve advanced and optimized synergistic efficacy. Moreover, more versatile mechanisms for controlled release can be achieved by incorporating versatile stimuli-responsive materials, such as pH-responsive,10 glucose-responsive,57 and ion-responsive ones,58 in the heterogeneous shell.

Our technique that involves all-aqueous droplet templates provides a

versatile and green strategy for controllable fabrication of multi-compartmental capsules for coencapsulation of versatile incompatible components, or even sensitive biomolecules for applications such as synergistic drug delivery, confined reaction, cell culture, and enzyme immobilization.


21


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 47

ASSOCIATED CONTENT: Supporting

Information

Available:

FESEM

image of the PNIPAM nanogels that used as

functional gates for the synergistic release, movies of the coalescence process of two W/W droplets triggered by a stainless steel needle for fabricating dual-compartmental capsules, the magnetic-guided rotational motion of a dual-compartmental capsule, and the magnetic-guided translational movement of the dual-compartmental capsules. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Authors * E-mail: [email protected] (L.-Y. Chu); [email protected] (W. Wang). Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS The authors gratefully acknowledge support from the National Natural Science Foundation of China (91434202, 81321002), the Program for Changjiang Scholars and Innovative Research


22

Page 23 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Team in University (IRT15R48) and State Key Laboratory of Polymer Materials Engineering (sklpme2014-1-01).

REFERENCES (1) Wang, W.; Zhang, M. J.; Chu, L. Y., Functional Polymeric Microparticles Engineered from Controllable Microfluidic Emulsions. Acc. Chem. Res. 2014, 47, 373-384. (2) Choi, S. W.; Zhang, Y.; Xia, Y. N., Fabrication of Microbeads with a Controllable Hollow Interior and Porous Wall Using a Capillary Fluidic Device. Adv. Funct. Mater. 2009, 19, 2943-2949. (3) De Rose, R.; Zelikin, A. N.; Johnston, A. P. R.; Sexton, A.; Chong, S. F.; Cortez, C.; Mulholland, W.; Caruso, F.; Kent, S. J., Binding, Internalization, and Antigen Presentation of Vaccine-Loaded Nanoengineered Capsules in Blood. Adv. Mater. 2008, 20, 4698-4703. (4) Orive, G.; Santos, E.; Poncelet, D.; Hernández, R. M.; Pedraz, J. L.; Wahlberg, L. U.; De Vos, P.; Emerich, D., Cell Encapsulation: Technical and Clinical Advances. Trends Pharmacol. Sci. 2015, 36, 537-546. (5) Nguyen, D. K.; Son, Y. M.; Lee, N. E., Hydrogel Encapsulation of Cells in Core-Shell Microcapsules for Cell Delivery. Adv. Healthcare Mater. 2015, 4, 1537-1544. (6) Rao, W.; Zhao, S. T.; Yu, J. H.; Lu, X. B.; Zynger, D. L.; He, X. M., Enhanced Enrichment of Prostate Cancer Stem-Like Cells with Miniaturized 3D Culture in Liquid Core-Hydrogel Shell Microcapsules. Biomaterials 2014, 35, 7762-7773. (7) Qu, Y. N.; Huang, R. L.; Qi, W.; Su, R. X.; He, Z. M., Interfacial Polymerization of Dopamine in a Pickering Emulsion: Synthesis of Cross-Linkable Colloidosomes and


23


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 47

Enzyme Immobilization at Oil/Water Interfaces. ACS Appl. Mater. Interfaces 2015, 7, 14954-14964. (8) Huang, R. L.; Wu, S. K.; Li, A. T.; Li, Z., Integrating Interfacial Self-Assembly and Electrostatic Complexation at an Aqueous Interface for Capsule Synthesis and Enzyme Immobilization. J. Mater. Chem. A 2014, 2, 1672-1676. (9) Blum, C.; Nichtl, A.; Scheibel, T., Spider Silk Capsules as Protective Reaction Containers for Enzymes. Adv. Funct. Mater. 2014, 24, 763-768. (10) Wei, J.; Ju, X. J.; Zou, X. Y.; Xie, R.; Wang, W.; Liu, Y. M.; Chu, L. Y., Multi-StimuliResponsive Microcapsules for Adjustable Controlled-Release. Adv. Funct. Mater. 2014, 24, 3312-3323. (11) Ping, Y.; Guo, J. L.; Ejima, H.; Chen, X.; Richardson, J. J.; Sun, H. L.; Caruso, F., pHResponsive Capsules Engineered from Metal-Phenolic Networks for Anticancer Drug Delivery. Small 2015, 11, 2032-2036. (12) Esser-Kahn, A. P.; Odom, S. A.; Sottos, N. R.; White, S. R.; Moore, J. S., Triggered Release from Polymer Capsules. Macromolecules 2011, 44, 5539-5553. (13) Choi, W. S.; Park, J. H.; Koo, H. Y.; Kim, J. Y.; Cho, B. K.; Kim, D. Y., "Grafting-from" Polymerization inside a Polyelectrolyte Hollow-Capsule Microreactor. Angew. Chem., Int. Ed. 2005, 44, 1096-1101. (14) Duan, L.; He, Q.; Wang, K. W.; Yan, X. H.; Cui, Y.; Moewald, H.; Li, J. B., Adenosine Triphosphate Biosynthesis Catalyzed by F0F1 ATP Synthase Assembled in Polymer Microcapsules. Angew. Chem., Int. Ed. 2007, 46, 6996-7000. (15) He, Q.; Duan, L.; Qi, W.; Wang, K. W.; Cui, Y.; Yan, X. H.; Li, J. B., Microcapsules Containing a Biomolecular Motor for ATP Biosynthesis. Adv. Mater. 2008, 20, 2933-2937.


24

Page 25 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(16) de Hoog, H. P. M.; Nallani, M.; Tomczak, N., Self-Assembled Architectures with Multiple Aqueous Compartments. Soft Matter 2012, 8, 4552-4561. (17) Villar, G.; Heron, A. J.; Bayley, H., Formation of Droplet Networks That Function in Aqueous Environments. Nat. Nanotechnol. 2011, 6, 803-808. (18) Johnston, A. P. R.; Such, G. K.; Caruso, F., Triggering Release of Encapsulated Cargo. Angew. Chem., Int. Ed. 2010, 49, 2664-2666. (19) Sun, B. J.; Shum, H. C.; Holtze, C.; Weitz, D. A., Microfluidic Melt Emulsification for Encapsulation and Release of Actives. ACS Appl. Mater. Interfaces 2010, 2, 3411-3416. (20) Kisak, E. T.; Coldren, B.; Evans, C. A.; Boyer, C.; Zasadzinski, J. A., The Vesosome - a Multicompartment Drug Delivery Vehicle. Curr. Med. Chem. 2004, 11, 199-219. (21) Peters, R. J. R. W.; Marguet, M.; Marais, S.; Fraaije, M. W.; van Hest, J. C. M.; Lecommandoux, S., Cascade Reactions in Multicompartmentalized Polymersomes. Angew. Chem., Int. Ed. 2014, 53, 146-150. (22) Huang, X.; Voit, B., Progress on Multi-Compartment Polymeric Capsules. Polym. Chem. 2013, 4, 435-443. (23) Kreft, O.; Prevot, M.; Mohwald, H.; Sukhorukov, G. B., Shell-in-Shell Microcapsules: A Novel Tool for Integrated, Spatially Confined Enzymatic Reactions. Angew. Chem., Int. Ed. 2007, 46, 5605-5608. (24) Kreft, O.; Skirtach, A. G.; Sukhorukov, G. B.; Mohwald, H., Remote Control of Bioreactions in Multicompartment Capsules. Adv. Mater. 2007, 19, 3142-3145. (25) Elani, Y.; Gee, A.; Law, R. V.; Ces, O., Engineering Multi-Compartment Vesicle Networks. Chem. Sci. 2013, 4, 3332-3338.


25


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 47

(26) Elani, Y.; Law, R. V.; Ces, O., Vesicle-Based Artificial Cells as Chemical Microreactors with Spatially Segregated Reaction Pathways. Nat. Commun. 2014, 5, 5305. (27) Chen, H. Y.; Zhao, Y.; Song, Y. L.; Jiang, L., One-Step Multicomponent Encapsulation by Compound-Fluidic Electrospray. J. Am. Chem. Soc. 2008, 130, 7800-7801. (28) Wang, W.; Xie, R.; Ju, X. J.; Luo, T.; Liu, L.; Weitz, D. A.; Chu, L. Y., Controllable Microfluidic Production of Multicomponent Multiple Emulsions. Lab Chip 2011, 11, 15871592. (29) Chu, L. Y.; Utada, A. S.; Shah, R. K.; Kim, J. W.; Weitz, D. A., Controllable Monodisperse Multiple Emulsions. Angew. Chem., Int. Ed. 2007, 46, 8970-8974. (30) Abate,

A.

R.;

Weitz,

D.

A.,

High-Order

Multiple

Emulsions

Formed

in

Poly(Dimethylsiloxane) Microfluidics. Small 2009, 5, 2030-2032. (31) Utada, A. S.; Lorenceau, E.; Link, D. R.; Kaplan, P. D.; Stone, H. A.; Weitz, D. A., Monodisperse Double Emulsions Generated from a Microcapillary Device. Science 2005, 308, 537-541. (32) Shum, H. C.; Zhao, Y. J.; Kim, S. H.; Weitz, D. A., Multicompartment Polymersomes from Double Emulsions. Angew. Chem., Int. Ed. 2011, 50, 1648-1651. (33) Wang, W.; Luo, T.; Ju, X. J.; Xie, R.; Liu, L.; Chu, L. Y., Microfluidic Preparation of Multicompartment Microcapsules for Isolated Co-Encapsulation and Controlled Release of Diverse Components. Int. J. Nonlinear Sci. Numer. Simul. 2012, 13, 325-332. (34) Kim, S. H.; Shum, H. C.; Kim, J. W.; Cho, J. C.; Weitz, D. A., Multiple Polymersomes for Programmed Release of Multiple Components. J. Am. Chem. Soc. 2011, 133, 15165-15171.


26

Page 27 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(35) Windbergs, M.; Zhao, Y.; Heyman, J.; Weitz, D. A., Biodegradable Core-Shell Carriers for Simultaneous Encapsulation of Synergistic Actives. J. Am. Chem. Soc. 2013, 135, 79337937. (36) Lee, S. S.; Abbaspourrad, A.; Kim, S. H., Nonspherical Double Emulsions with Multiple Distinct Cores Enveloped by Ultrathin Shells. ACS Appl. Mater. Interfaces 2014, 6, 12941300. (37) Perro, A.; Nicolet, C.; Angy, J.; Lecommandoux, S.; Le Meins, J. F.; Colin, A., Mastering a Double Emulsion in a Simple Co-Flow Microfluidic to Generate Complex Polymersomes. Langmuir 2011, 27, 9034-9042. (38) Lee, K. Y.; Mooney, D. J., Alginate: Properties and Biomedical Applications. Prog. Polym. Sci. 2012, 37, 106-126. (39) Sugiura, S.; Oda, T.; Izumida, Y.; Aoyagi, Y.; Satake, M.; Ochiai, A.; Ohkohchi, N.; Nakajima, M., Size Control of Calcium Alginate Beads Containing Living Cells Using Micro-Nozzle Array. Biomaterials 2005, 26, 3327-3331. (40) Maeda, K.; Onoe, H.; Takinoue, M.; Takeuchi, S., Controlled Synthesis of 3D MultiCompartmental Particles with Centrifuge-Based Microdroplet Formation from a MultiBarrelled Capillary. Adv. Mater. 2012, 24, 1340-1346. (41) Liu, Z.; Shum, H. C., Fabrication of Uniform Multi-Compartment Particles Using Microfludic Electrospray Technology for Cell Co-Culture Studies. Biomicrofluidics 2013, 7, 044117. (42) Chen, Q. L.; Liu, Z.; Shum, H. C., Three-Dimensional Printing-Based Electro-Millifluidic Devices for Fabricating Multi-Compartment Particles. Biomicrofluidics 2014, 8, 064112.


27


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 47

(43) Lu, Y. C.; Song, W.; An, D.; Kim, B. J.; Schwartz, R.; Wu, M. M.; Ma, M. L., Designing Compartmentalized Hydrogel Microparticles for Cell Encapsulation and Scalable 3D Cell Culture. J. Mater. Chem. B 2015, 3, 353-360. (44) Jain, D.; Bar-Shalom, D., Alginate Drug Delivery Systems: Application in Context of Pharmaceutical and Biomedical Research. Drug Dev. Ind. Pharm. 2014, 40, 1576-1584. (45) de Vos, P.; Faas, M. M.; Strand, B.; Calafiore, R., Alginate-Based Microcapsules for Immunoisolation of Pancreatic Islets. Biomaterials 2006, 27, 5603-5617. (46) Chan, K. W. Y.; Liu, G. S.; Song, X. L.; Kim, H.; Yu, T.; Arifin, D. R.; Gilad, A. A.; Hanes, J.; Walczak, P.; van Zijl, P. C. M.; Bulte, J. W. M.; McMahon, M. T., MRI-Detectable pH Nanosensors Incorporated into Hydrogels for in Vivo Sensing of Transplanted-Cell Viability. Nat. Mater. 2013, 12, 268-275. (47) Wang, J. Y.; Jin, Y.; Xie, R.; Liu, J. Y.; Ju, X. J.; Meng, T.; Chu, L. Y., Novel CalciumAlginate Capsules with Aqueous Core and Thermo-Responsive Membrane. J. Colloid Interface Sci. 2011, 353, 61-68. (48) He, X. H.; Wang, W.; Liu, Y. M.; Jiang, M. Y.; Wu, F.; Deng, K.; Liu, Z.; Ju, X. J.; Xie, R.; Chu, L. Y., Microfluidic Fabrication of Bio-Inspired Microfibers with Controllable Magnetic Spindle-Knots for 3D Assembly and Water Collection. ACS Appl. Mater. Interfaces 2015, 7, 17471-17481. (49) Pelton, R., Temperature-Sensitive Aqueous Microgels. Adv. Colloid Interface Sci. 2000, 85, 1-33. (50) Mei, L.; Xie, R.; Yang, C.; Ju, X. J.; Wang, J. Y.; Zhang, Z. B.; Chu, L. Y., Bio-Inspired Mini-Eggs with pH-Responsive Membrane for Enzyme Immobilization. J. Membr. Sci. 2013, 429, 313-322.


28

Page 29 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(51) He, F.; Mei, L.; Ju, X. J.; Xie, R.; Wang, W.; Liu, Z.; Wu, F.; Chu, L. Y., pH-Responsive Controlled Release Characteristics of Solutes with Different Molecular Weights Diffusing across Membranes of Ca-Alginate/Protamine/Silica Hybrid Capsules. J. Membr. Sci. 2015, 474, 233-243. (52) Gombotz, W. R.; Wee, S. F., Protein Release from Alginate Matrices. Adv. Drug Delivery Reviews 1998, 31, 267-285. (53) Bremond, N.; Santanach-Carreras, E.; Chu, L. Y.; Bibette, J., Formation of Liquid-Core Capsules Having a Thin Hydrogel Membrane: Liquid Pearls. Soft Matter 2010, 6, 24842488. (54) Mele, E.; Fragouli, D.; Ruffilli, R.; Gregorio, G. L. D.; Cingolani, R.; Athanassiou, A., Complex Architectures Formed by Alginate Drops Floating on Liquid Surfaces. Soft Matter 2013, 9, 6338-6343. (55) Kono, K.; Kawakami, K.; Morimoto, K.; Takagishi, T., Effect of Hydrophobic Units on the pH-Responsive Release Property of Polyelectrolyte Complex Capsules. J. Appl. Polym. Sci. 1999, 72, 1763-1773. (56) Takamura, K.; Koishi, M.; Kondo, T., Studies on Microcapsules. IX: Permeability of Polyphthalamide Microcapsule Membranes to Electrolytes. Kolloid Z. Z. Polym. 1971, 248, 929-933. (57) Zhang, M. J.; Wang, W.; Xie, R.; Ju, X. J.; Liu, L.; Gu, Y. Y.; Chu, L. Y., Microfluidic Fabrication of Monodisperse Microcapsules for Glucose-Response at Physiological Temperature. Soft Matter 2013, 9, 4150-4159. (58) Liu, Z.; Liu, L.; Ju, X. J.; Xie, R.; Zhang, B.; Chu, L. Y., K+-Recognition Capsules with Squirting Release Mechanisms. Chem. Commun. 2011, 47, 12283-12285.


29


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 47

Figures

Figure 1. Co-extrusion minifluidic devices for fabrication of dual-compartmental Ca-Alg capsules. (a) Schematic illustration of the co-extrusion minifluidic device for fabricating W/W droplets. (b) Schematic illustration showing the combination of two co-extrusion minifluidic devices for fabricating the dual-compartmental Ca-Alg capsules. (c-e) Digital photos showing the generation of two different W/W droplets at the outlets of the devices (c), the coalescence of


30

Page 31 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


the two W/W droplets triggered by the stainless steel needle (d), and the formation of dualcompartmental Ca-Alg capsules in the Ca(NO3)2 solution (e). Folic acid (yellow color) is added in the core compartment of one W/W droplets for labelling. The scale bars are 2.5 mm. (f-h) Schematic illustrations showing the crosslinking mechanism of alginate in the shell solution (f) by crosslinking with Ca2+ from the Ca(NO3)2 solution (g) via formation of egg-box structures (h).


31


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 32 of 47

Figure 2. Effect of falling height (H) on the structure of dual-compartmental Ca-Alg capsules. (a) High-speed snapshots showing the formation of a Ca-Alg dual-compartmental capsule with one compartment containing folic acid (white color) (H=2.8 cm) in the Ca2+-containing solution. (b) Digital photos of the Ca-Alg dual-compartmental capsules with one compartment containing folic acid (yellow color) fabricated at different H values. The scale bars are 2.5 mm in (a) and 3 mm in (b).


32

Page 33 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. Controllable dual-compartmental Ca-Alg capsules for co-encapsulation. (a) Digital photos of capsules with one of the dual-compartments containing folic acid (yellow color). (b) Flow-rate-dependent control of the ratio of the volume (VIF1) of the compartment without folic acid to that (VIF2) of the compartment with folic acid. (c, d) Fluorescent (c) and CLSM (d) images of capsules with one of the dual-compartments containing FITC-dextran (green fluorescence), with a separate shell between the two compartments to isolate the encapsulants for avoiding cross-contamination. In (a), (c) and (d), the capsules are prepared when QIF1/(QIF1+QOF1) and QIF2/(QIF2+QOF2) are both kept at 4/7. The scale bars are 5 mm in (a), 2 mm in (c) and 500 μm in (d).


33


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 34 of 47

Figure 4. Magnetic manipulation of dual-compartmental Ca-Alg capsules with magnetic nanoparticles (MNPs) dispersed in one of the compartments. (a) Digital photos showing the magnetic-guided rotational motion of the capsules. (b) Digital photos showing the magneticguided translational movement of the capsules. The scale bars are 2.5 mm (a) and 8 mm in (b).


34

Page 35 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. Dual-compartmental Ca-Alg capsules with Janus shell. (a) Schematic illustration (a1) and digital photos (a2, a3) showing dual-compartmental Ca-Alg capsules, containing Janus shell with one half dyed with Disperse Red and the other half dyed with Disperse Blue. (b, c) CLSM images that focus on the outer shell and the separate shell of dual-compartmental Ca-Alg capsules, containing Janus shell with one half dyed with FITC-dextran (green fluorescence). The scale bars are 3 mm in (a2), 1.5 mm in (a3), 500 μm (b), and 400 μm in (c).


35


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 36 of 47

Figure 6. Dual-compartmental Ca-Alg capsules with distinct cores and Janus shell for synergistic release of different encapsulants. (a) Schematic illustration showing the synergistic release behaviors of the capsules with thermo-responsive nanogels embedded in one half of the Janus shell.

(b) CLSM image of a dual-compartmental capsule with TRITC-dextran (red

fluorescence) loaded in one compartment with Ca-Alg shell, and with FITC-dextran (green fluorescence) loaded in the other compartment with nanogel-embedded Ca-Alg shell. The scale


36

Page 37 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


bar is 500 μm. (c) Temperature-dependent diameter change of the PNIPAM nanogels in water. (d-f) Accumulated release (d), plots of ln[(Cf-Ci)/(Cf-Ct)] versus t (e) and diffusional permeability coefficient (P) of the solute molecules (f) across the Janus shell of the dualcompartmental capsules at different temperatures.


37


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 38 of 47

Figure 7. Scale-up of the devices for fabrication of triple-compartmental Ca-Alg capsules. (a) Schematic illustration showing the combination of three co-extrusion minifluidic devices for fabricating triple-compartmental Ca-Alg capsules. (b) Digital photo of the triple-compartmental Ca-Alg capsules, with two of the compartments respectively dyed with folic acid (yellow color) and Disperse Red. The scale bar is 5 mm.


38

Page 39 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Graphic for TOC


39


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 1. Co-extrusion minifluidic devices for fabrication of dual-compartmental Ca-Alg capsules. (a) Schematic illustration of the co-extrusion minifluidic device for fabricating W/W droplets. (b) Schematic illustration showing the combination of two co-extrusion minifluidic devices for fabricating the dualcompartmental Ca-Alg capsules. (c-e) Digital photos showing the generation of two different W/W droplets at the outlets of the devices (c), the coalescence of the two W/W droplets triggered by the stainless steel needle (d), and the formation of dual-compartmental Ca-Alg capsules in the Ca(NO3)2 solution (e). Folic acid (yellow color) is added in the core compartment of one W/W droplets for labelling. The scale bars are 2.5 mm. (f-h) Schematic illustrations showing the crosslinking mechanism of alginate in the shell solution (f) by crosslinking with Ca2+ from the Ca(NO3)2 solution (g) via formation of egg-box structures (h). 80x108mm (300 x 300 DPI)


Page 40 of 47

Page 41 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. Effect of falling height (H) on the structure of dual-compartmental Ca-Alg capsules. (a) Highspeed snapshots showing the formation of a Ca-Alg dual-compartmental capsule with one compartment containing folic acid (white color) (H=2.8 cm) in the Ca2+-containing solution. (b) Digital photos of the CaAlg dual-compartmental capsules with one compartment containing folic acid (yellow color) fabricated at different H values. The scale bars are 2.5 mm in (a) and 3 mm in (b). 160x138mm (300 x 300 DPI)



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 3. Controllable dual-compartmental Ca-Alg capsules for co-encapsulation. (a) Digital photos of capsules with one of the dual-compartments containing folic acid (yellow color). (b) Flow-rate-dependent control of the ratio of the volume (VIF1) of the compartment without folic acid to that (VIF2) of the compartment with folic acid. (c, d) Fluorescent (c) and CLSM (d) images of capsules with one of the dualcompartments containing FITC-dextran (green fluorescence), with a separate shell between the two compartments to isolate the encapsulants for avoiding cross-contamination. In (a), (c) and (d), the capsules are prepared when QIF1/(QIF1+QOF1) and QIF2/(QIF2+QOF2) are both kept at 4/7. The scale bars are 5 mm in (a), 2 mm in (c) and 500 µm in (d). 160x157mm (300 x 300 DPI)


Page 42 of 47

Page 43 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. Magnetic manipulation of dual-compartmental Ca-Alg capsules with magnetic nanoparticles (MNPs) dispersed in one of the compartments. (a) Digital photos showing the magnetic-guided rotational motion of the capsules. (b) Digital photos showing the magnetic-guided translational movement of the capsules. The scale bars are 2.5 mm (a) and 8 mm in (b). 159x81mm (300 x 300 DPI)



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 5. Dual-compartmental Ca-Alg capsules with Janus shell. (a) Schematic illustration (a1) and digital photos (a2, a3) showing dual-compartmental Ca-Alg capsules, containing Janus shell with one half dyed with Disperse Red and the other half dyed with Disperse Blue. (b, c) CLSM images that focus on the outer shell and the separate shell of dual-compartmental Ca-Alg capsules, containing Janus shell with one half dyed with FITC-dextran (green fluorescence). The scale bars are 3 mm in (a2), 1.5 mm in (a3), 500 µm (b), and 400 µm in (c). 160x155mm (300 x 300 DPI)


Page 44 of 47

Page 45 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 6. Dual-compartmental Ca-Alg capsules with distinct cores and Janus shell for synergistic release of different encapsulants. (a) Schematic illustration showing the synergistic release behaviors of the capsules with thermo-responsive nanogels embedded in one half of the Janus shell. (b) CLSM image of a dualcompartmental capsule with TRITC-dextran (red fluorescence) loaded in one compartment with Ca-Alg shell, and with FITC-dextran (green fluorescence) loaded in the other compartment with nanogel-embedded CaAlg shell. The scale bar is 500 µm. (c) Temperature-dependent diameter change of the PNIPAM nanogels in water. (d-f) Accumulated release (d), plots of ln[(Cf-Ci)/(Cf-Ct)] versus t (e) and diffusional permeability coefficient (P) of the solute molecules (f) across the Janus shell of the dual-compartmental capsules at different temperatures. 160x181mm (300 x 300 DPI)



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 7. Scale-up of the devices for fabrication of triple-compartmental Ca-Alg capsules. (a) Schematic illustration showing the combination of three co-extrusion minifluidic devices for fabricating triplecompartmental Ca-Alg capsules. (b) Digital photo of the triple-compartmental Ca-Alg capsules, with two of the compartments respectively dyed with folic acid (yellow color) and Disperse Red. The scale bar is 5 mm. 79x156mm (300 x 300 DPI)


Page 46 of 47

Page 47 of 47

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Graphic for TOC 80x39mm (300 x 300 DPI)


Controllable Multicompartmental Capsules with Distinct Cores and

Recommend Documents