Hierarchical Lotus Leaf-Like Mesoporous Silica Material with Unique

Subscriber access provided by UNIVERSITY OF SOUTH CAROLINA LIBRARIES

Letter

Hierarchical Lotus Leaf-like Mesoporous Silica Material with Unique Bilayer and Hollow Sandwich-like Folds: Synthesis, Mechanism, and Applications Nanjing Hao, Hamid Chorsi, and John X.J. Zhang ACS Sustainable Chem. Eng., Just Accepted Manuscript • Publication Date (Web): 20 Feb 2017 Downloaded from http://pubs.acs.org on February 21, 2017

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 Sustainable Chemistry & Engineering 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 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

ACS Sustainable Chemistry & Engineering

Hierarchical Lotus Leaf-like Mesoporous Silica Material with Unique Bilayer and Hollow Sandwich-like Folds: Synthesis, Mechanism, and Applications Nanjing Hao, Hamid T. Chorsi, and John X. J. Zhang* Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755, United States. *E-mail: [email protected] KEYWORDS: mesoporous silica, hierarchical, shape, lotus leaf, hollow

ABSTRACT: A facile and straightforward strategy was developed to synthesize hierarchical lotus leaf-like mesoporous silica material (LLMSM) with unique bilayer and hollow sandwichlike folds using hexadecylamine as structure-directing agent, high molecular weight polyvinylpyrrolidone as structure-stabilizing agent, and tetraethyl orthosilicate as silica precursor in the mixed solvents of water and ethanol. The formation mechanism of LLMSM was proposed based on a series of experimental investigations. This new particulate platform exhibited superior adsorption capacity toward organic dye, effective catalytic reduction of 4-nitrophenol as Ag catalyst supporter, and multistage sustained drug release profile. Many other applications can be also envisaged for such hierarchical structure.

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 17

Since its first discovery in the early 1990s,1 mesoporous silica material (MSM) has attracted extensively interests in various fields, such as energy, catalysis, adsorption, separation, and biomedicine. To maximize its efficacy and effectiveness, considerable efforts have been devoted to the rational design of such material to suit specific application needs through controlling the physicochemical properties, including particle size, surface chemistry, and pore types.2,3 However, more and more evidences from both theoretical and experimental aspects have recently revealed that particle shape could also significantly affect its performance, especially for those processes involving mass transfer.4–7 These findings not only help to shed new light on the shape genesis of MSM but also inspire researchers to develop MSM of various shapes. To date, many strategies have already been employed for the synthesis of different shapes of MSM, such as sphere,8 ellipsoid,7 rod,9 sheet,10 platelet,11 and some corresponding hollow counterparts.12–14 However, most of these shapes possessed only single or simple architecture and pore arrangement, which may restrict the availabilities of certain pore channels for mass transfer. Comparatively, hierarchical three dimensional porous structures with complex shapes could provide more exposed pore openings and pore arrangements, which may improve the accessibility of pore channels inside of MSM and thus greatly favored for many application fields, such as adsorption and catalysis.15,16 However, despite significant and increasing needs, facile and stable synthesis of hierarchical porous silica material, especially having short pore path lengths and rich pore structures, is still an outstanding challenge. Herein, we report a facile one-pot strategy to synthesize hierarchical lotus leaf-like mesoporous silica material (LLMSM) with unique bilayer and hollow sandwich-like folds using hexadecylamine (HDA) as structure-directing agent, high molecular weight polyvinylpyrrolidone (PVP) as structure-stabilizing agent, and tetraethyl orthosilicate (TEOS) as silica precursor in the


2

Page 3 of 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


mixed solvents of water and ethanol. The formation mechanism of LLMSM was explored through a series of experimental investigations. The adsorption, catalytic, and sustained drug release performances of this hierarchical structure-based platforms were also examined (Scheme 1).

Scheme 1. Synthesis of LLMSM with unique bilayer and hollow sandwich-like folds as efficient adsorbent, catalyst supporter, and drug carrier. Hierarchical porous silica material having unique bilayer and hollow sandwich-like folds can be successfully synthesized using only HDA, PVP, and TEOS in the mixed water and ethanol solution (See experimental details in the Supporting Information). As shown in Figure 1, lotus leaf-like silica material displayed a unique layered architecture and typical folded protuberance. This LLMSM has an average size of ~4 µm and an average thickness of ~150 nm. Both the edge region and the inside region of LLMSM showed clearly porous structures (Figure S1), and multiple pore size distributions can be investigated especially from the folds of the edge region (Figures 1C, 1F, and S1A). From the broken particles (Figure S2), the existence of a bilayered structure was further confirmed when combined with the observations from hollow sandwichlike folds (Figure 1C). In addition, the thickness of this hierarchical mesoporous silica structure can be easily tuned from ~30 to ~400 nm by just changing the concentration of silica precursor (TEOS) (Figure S3). N2 adsorption-desorption analysis was then performed on the as-


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 17

synthesized LLMSM after removing HDA and PVP via the extraction method (Figure S4). The results showed that LLMSM exhibited typical type IV isotherm with H3 hysteresis (Figure S5), indicating the presence of slit-shaped and large-sized porous structures.17,18 The pore size of LLMSM was calculated to be 2.95 nm by the Barrett-Joyner-Halenda (BJH) method (Figure S5B), and multiple pore size distribution are also in agreement with the observations from TEM and SEM images (Figures 1 and S5B). The Brunauer-Emmett-Teller (BET) surface area and pore volume were measured to be 806.5 m2/g and 0.76 cm3/g, respectively.

Figure 1. Scanning electron microscopy (SEM) images (A-C) and transmission electron microscopy (TEM) images (D-F) of as-synthesized hierarchical mesoporous silica material with unique bilayer and hollow sandwich-like folds. The inset in Figure A is the image of a lotus leaf. To explore the formation mechanism of this hierarchical porous silica structure with unique bilayer and hollow sandwich-like folds, we carried out a series of experiments to investigate the specific roles of TEOS, PVP, and HDA in the reaction system. As mentioned above, TEOS as silica precursor played main roles in the regulation of material thickness, but had minor effects on their hierarchical shapes (Figure S3). Thus, the effects of PVP and HDA on the formation of


4

Page 5 of 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


LLMSM were primarily investigated. In the absence of PVP, hierarchical silica material still can be obtained, but there is no well-defined lotus leaf-like structure with typical folds, and severe aggregations can be observed (Figure S6). This phenomenon provided direct evidences that PVP and HDA played the structure-stabilizing role and the structure-directing role in the synthesis process of LLMSM, respectively. If the concentration of PVP is decreased in the reaction system, hierarchical silica structure with typical hollow sandwich-like folds still can be produced (Figure S7). However, increasing the concentration of PVP can only yield hierarchical silica structure with solid folds (Figure S8), which may be caused from the excessive recruitment of silica precursors by PVP molecules and then evolving into more dense and compact structures. The molecular weight of PVP also significantly affects the fine structures of the as-synthesized materials. Compared to high molecular weight of PVP for producing typical hollow sandwichlike folds, low molecular weight of PVP can only produce tiny wrinkled protuberance (Figure S9). These results not only confirmed the role of PVP as the structure-stabilizing agent but also revealed the functions of PVP molecules on the formation of layered and folded morphologies. Next, the effects of HDA on the formation of LLMSM were explored in a series of studies. Without the addition of HDA, there is no obvious product formed, and there are only disordered nanoparticles formed by changing HDA to ammonia (Figure S10), indicating that HDA not only played a structure-directing role but also acted as a catalyst for catalyzing hydrolysis of TEOS. In addition, we found that decreasing the concentration of HDA in the reaction system can still yield hierarchical product but with less folds (Figure S11), while increasing the concentration of HDA can yield hierarchical product with more typical folds in the edge region (Figure S12), which further confirmed its roles as structure-directing agent and catalyst.


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 17

Based on the above observations, a region-dependent growth mechanism of LLMSM with unique bilayer and hollow sandwich-like folds was proposed (Scheme 2). In the inside region, high molecular weight of PVP molecules with strong polar pyrrolidone rings can firstly bind with HDA to form bilayered skeleton,19 then TEOS will be attracted to the positive ends of the polar groups of PVP molecules and deposited around their linear and random coil surface. Considering the relatively higher external surface pressure,20 more compact and flat bilayered mesoporous silica structure will be formed in the inside region (Scheme 2), which can be also confirmed by the above observations (Figures 1, S2, and S5). Comparatively, in the edge region, the diffusion of ethanol into the bilayered micelles could reduce the interaction of the alkyl tails,21 which thus increase the hydrophobic volume of the bilayered micelles. This situation further induces the formation of hollow sandwich-like folds by reducing the surface energy of the edge region of the bilayered micelles (Scheme 2).


6

Page 7 of 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


Scheme 2. Proposed mechanism for the formation of hierarchical mesoporous silica material with unique bilayer and hollow sandwich-like folds. Because of its hierarchical three dimensional structures, unique bilayer, typical hollow sandwich-like folds, large specific surface area, and high pore volume, the as-synthesized LLMSM could be favored in many application fields, especially for those involving adsorption and diffusion. To demonstrate this, the adsorption capacity of LLMSM was firstly examined using an organic dye, rhodamine B. As shown in Figure 2A, even at a low mass ratio of adsorbent (LLMSM) to adsorbate (rhodamine B) (see details in the Supporting Information),22–24 the characteristic absorption of rhodamine B at 550 nm decreased dramatically in the first 5 min. This reason, except for the electrostatic interaction between negatively charged silicate surface and positively charged rhodamine B, may be probably attributed to the special morphology of LLMSM with unique bilayer and hollow sandwich-like folds. Subsequently, the remaining concentration of rhodamine B slowed down with the increasing adsorption time (Figure 2A), which is in accordance with the sample photos recorded at corresponding different time intervals (Figure 2B, inset). The removal rate of rhodamine B by LLMSM as a function of time also clearly showed that this adsorption process is rapid, especially in the initial stage, which is in agreement with the results from UV-vis spectra. After 60 min, rhodamine B can be almost completely removed leaving a nearly clear solution, and the color of the adsorbent changed from white to pink (Figure 2B, inset). The maximum adsorption capacity of rhodamine B by LLMSM was further determined to be as high as 530.7 mg per gram silica material (see details in the Supporting Information), reflecting a good adsorption capacity of LLMSM (Table S1).


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 17

Figure 2. (A) UV-vis spectra for time dependent adsorption of rhodamine B in the presence of LLMSM under dark conditions. (B) Adsorption rate of rhodamine B by LLMSM. C0 is the initial concentration of the rhodamine B solution, and C is the concentration of that at different time intervals during the adsorption. Error bars show the standard deviations from three independent tests. One inset is the photograph of a group of rhodamine solutions at varying times and the other inset represents the photographs of LLMSM before and after adsorption. To explore its potential application in catalysis on behalf of hierarchical mesoporous structures, LLMSM was then employed as Ag catalyst supporter for performing the catalytic reduction of 4nitrophenol. As shown in Figure 3, Ag nanoparticles were distributed randomly in LLMSM. It is also noted that, in addition to obviously large-sized Ag nanoparticles, many small-sized Ag nanoparticles are actually presented inside of the nanoporous matrix (Figure 3C). An evaluation of 200 Ag nanoparticles selected from the TEM images showed that the size of most Ag nanoparticles is less than 3 nm (Figure 3C, inset), and the lattice fringe spacing of 0.235 nm agrees well with the interplanar distance of the (111) plane of Ag crystal (Figure 3C, inset).10 The content of Ag in LLMSM was determined to be 8.96% in weight by energy-dispersive X-ray analysis (Figure S13). The catalytic activity of Ag-loaded LLMSM was examined by the reduction reaction of 4-nitrophenol with an excess amount of sodium borohydride. In the absence


8

Page 9 of 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


of the catalyst (Ag-loaded LLMSM), the reaction did not proceed during a period of more than 24 h. The kinetics of 4-nitrophenol reduction was then monitored by UV-vis spectroscopy of the reaction mixture after the addition of the catalyst. As shown in Figure 3D, the typical absorption peak intensity at 400 nm gradually decreased with a concomitant increase in peaks intensity at 300 nm and 230 nm as the reduction reaction proceeded. The reaction processes can be also observed from the fading of yellow color to colorless after the addition of Ag-loaded LLMSM. A successive decrease of peak intensity at 400 nm with time was then taken into consideration to obtain the rate constant. The ratio of C to C0, where C0 and C are the initial concentration and the concentration of 4-nitrophenol at different times, respectively, was measured from the relative intensity ratio of the respective absorbance at 400 nm. A linear correlation between In(C/C0) and time can be revealed that the reaction process followed the pseudo first-order kinetics.7,25–27 Even at a relatively low mass ratio of catalyst (Ag-loaded LLMSM) to substrate (4-nitrophenol) (see details in the Supporting Information), the kinetic reaction rate constant k still can be achieved to 2.17 × 10-3 s-1 from the slope, indicating the superior performance of LLMSM-based catalytic supporter (Table S2).7,25–27 In addition, the reusability of Ag-loaded LLMSM was investigated. As shown in Figure 3E, after easily separated from the reaction mixture by mild centrifugation, Ag-loaded LLMSM can be reused for ten successive reactions and similar catalytic performance was observed. These results can be also revealed by the stable structure of Ag-loaded LLMSM after running for ten times (Figure S14), which further indicated that such hierarchical structure may find promising applications in catalysis.


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 17

Figure 3. (A-C) TEM images of Ag nanoparticles-loaded LLMSM at different magnifications. The insets in Figure C show the lattice pattern and the statistical size distribution of Ag nanoparticle (It is noted that, in addition to obviously large-sized Ag nanoparticles, many smallsized Ag nanoparticles are actually presented inside of the nanoporous matrix). (D) Time dependent UV-vis spectral changes of 4-nitrophenol catalyzed by the Ag-loaded LLMSM. The inset shows the reaction in the presence of Ag-loaded LLMSM. (E) Catalytic kinetics for ten successive cycles with the same batch of Ag-loaded LLMSM. Porous silica microparticles have recently gained great interests in tissue engineering and wound healing not only because of its robust role as scaffold but also because of its specific role as drug carrier.28–30 To demonstrate the potential applications of LLMSM in biomedical fields, doxorubicin (Dox) was chosen as a model drug for examining the drug loading capacity and release behavior of LLMSM. A linear standard calibration curve in the concentration range of


10

Page 11 of 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


0.625 to 20 µg mL-1 was firstly obtained for quantitatively determining the drug loading and releasing efficiency (Figure 4A). Based on this, the loading amount of Dox into LLMSM was calculated to achieve 463.4 mg per gram silica material (see details in the Supporting Information), indicating the superior capacity of LLMSM as reservoir for drug delivery (Table S3).13,28,30 The release profiles of Dox from Dox-loaded LLMSM (LLMSM-Dox) were measured in pH 4.5 and pH 7.4 phosphate buffered saline (PBS) to simulate different physiological environments. As shown in Figure 4B, Dox can be successfully and continuously released from LLMSM-Dox in both media over 6 days, and the release profiles displayed typical multistage and sustained properties, which can be probably attributed to the hierarchical structures of LLMSM having unique bilayer and hollow sandwich-like folds. The cumulative drug release rates were 80.1% and 27.8% after 6 days in pH 4.5 and pH 7.4 PBS, respectively (Figure 4B). This pH-dependent sustained release behavior makes LLMSM further attractive for meeting different needs in a controlled manner.

Figure 4. (A) UV-vis spectra of different concentrations of Dox in aqueous solution. The inset is the corresponding standard calibration curve of Dox at 233 nm (R2 =0.9997). (B) Sustained release profile of Dox from LLMSM-Dox in PBS buffer (pH 4.5 and pH 7.4). In summary, we first developed a facile one-pot strategy to synthesize well-defined lotus leaflike hierarchical mesoporous silica structure with unique bilayer and hollow sandwich-like folds


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

using

only

hexadecylamine

as

structure-directing

agent,

Page 12 of 17

high

molecular

weight

polyvinylpyrrolidone as structure-stabilizing agent, and tetraethyl orthosilicate as silica precursor in the mixed solvents of water and ethanol. The formation mechanism was proposed based on a series of experimental investigations. Such hierarchical structure exhibited rapid and highcapacity adsorption toward rhodamine B, displayed as an effective and stable catalyst supporter for the catalytic reduction of 4-nitrophenol, and also showed typical multistage and sustained drug release properties. Because of its hierarchical three dimensional structures, unique bilayer, typical hollow sandwich-like folds, large specific surface area, and high pore volume, this material holds a great promise in many application fields.

ASSOCIATED CONTENT Supporting Information Available: Experimental details, materials characterization and additional data. The Supporting Information is available free of charge on the ACS Publications website. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] ACKNOWLEDGMENT This work was sponsored by the NIH Director’s Transformative Research Award (1R01 HL119785-01), and NSF grants (ECCS 1128677, 1309686, 1509369). We gratefully acknowledge the support from the Electron Microscope Facility at Dartmouth College.


12

Page 13 of 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


REFERENCES (1) Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli, J. C.; Beck, J. S. Ordered Mesoporous Molecular Sieves Synthesized by a Liquid-Crystal Template Mechanism. Nature 1992, 359, 710–712. (2) Yang, P. P.; Gai, S. L.; Lin, J. Functionalized Mesoporous Silica Materials for Controlled Drug Delivery. Chem. Soc. Rev. 2012, 41, 3679–3698. (3) Hao, N. J.; Li, L. F.; Tang, F. Q. Roles of Particle Size, Shape and Surface Chemistry of Mesoporous Silica Nanomaterials on Biological Systems. Int. Mater. Rev. 2017, 62, 57-77. (4) Yang, K.; Ma, Y. Q. Computer Simulation of the Translocation of Nanoparticles with Different Shapes across a Lipid Bilayer. Nat. Nanotechnol. 2010, 5, 579–583. (5) Huang, X. L.; Li, L. L.; Liu, T. L.; Hao, N. J.; Liu, H. Y.; Chen, D.; Tang, F. Q. The Shape Effect of Mesoporous Silica Nanoparticles on Biodistribution, Clearance, and Biocompatibility in Vivo. ACS Nano 2011, 5, 5390–5399. (6) Sharma, T.; Hu, Y.; Stoller, M.; Feldman, M.; Ruoff, R. S.; Ferrari, M.; Zhang, X. Mesoporous Silica as A Membrane for Ultra-Thin Implantable Direct Glucose Fuel Cells. Lab Chip 2011, 11, 2460–2465. (7) Hao, N. J.; Li, L. F.; Tang, F. Q. Facile Preparation of Ellipsoid-like MCM-41 with Parallel Channels along the Short Axis for Drug Delivery and Assembly of Ag Nanoparticles for Catalysis. J. Mater. Chem. A 2014, 2, 11565–11568. (8) Du, X.; He, J. H. Spherical Silica Micro/nanomaterials with Hierarchical Structures: Synthesis and Applications. Nanoscale 2011, 3, 3984–4002. (9) Trewyn, B. G.; Nieweg, J. A.; Zhao, Y. N.; Lin, V. S.-Y. Biocompatible Mesoporous Silica Nanoparticles with Different Morphologies for Animal Cell Membrane Penetration. Chem. Eng.


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 17

J. 2008, 137, 23–29. (10) Edler, K. J.; Yang, B. Formation of Mesostructured Thin Films at the Air-Liquid Interface. Chem. Soc. Rev. 2013, 42, 3765–3776. (11) Chen, S. Y.; Tang, C. Y.; Chuang, W. T.; Lee, J. J.; Tsai, Y. L.; Chan, J. C.; Lin, C. Y.; Liu, Y. C.; Cheng, S. A Facile Route to Synthesizing Functionalized Mesoporous SBA-15 Materials with Platelet Morphology and Short Mesochannels. Chem. Mater. 2008, 20, 3906–3916. (12) Hao, N. J.; Li, L. F.; Tang, F. Q. Shape Matters When Engineering Mesoporous SilicaBased Nanomedicines. Biomater. Sci. 2016, 4, 575–591. (13) Hao, N. J.; Jayawardana, K. W.; Chen, X.; Yan, M. One-Step Synthesis of AmineFunctionalized Hollow Mesoporous Silica Nanoparticles as Efficient Antibacterial and Anticancer Materials. ACS Appl. Mater. Interfaces 2015, 7, 1040–1045. (14) Hao, N. J.; Chen, X.; Jeon, S.; Yan, M. Carbohydrate-Conjugated Hollow Oblate Mesoporous Silica Nanoparticles as Nanoantibiotics to Target Mycobacteria. Adv. Healthcare Mater. 2015, 4, 2797–2801. (15) Zhang, L.; Guo, Y.; Peng, J.; Liu, X.; Yuan, P.; Yang, Q.; Li, C. 3-D Flowerlike Architectures Constructed by Ultrathin Perpendicularly Aligned Mesoporous Nanoflakes for Enhanced Asymmetric Catalysis. Chem. Commun. 2011, 47, 4087–4089. (16) Shan, W.; Wang, B.; Zhang, Y.; Tang, Y. Fabrication of Lotus-Leaf-like Nanoporous Silica Flakes with Controlled Thickness. Chem. Commun. 2005, 61, 1877–1879. (17) Sing, K. S. W.; Everett, D. H.; Haul, R. A. W.; Moscou, L.; Pierotti, R. A.; Rouquerol, J.; Siemieniewska, T. Reporting Physisorption Data for Gas/solid Systems with Special Reference to the Determination of Surface Area and Porosity. Pure Appl. Chem. 1985, 57, 603–619.


14

Page 15 of 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


(18) Kruk, M.; Jaroniec, M. Gas Adsorption Characterization of Ordered Organic−Inorganic Nanocomposite Materials. Chem. Mater. 2001, 13, 3169–3183. (19) Koczkur, K. M.; Mourdikoudis, S.; Polavarapu, L.; Skrabalak, S. E. Polyvinylpyrrolidone (PVP) in Nanoparticle Synthesis. Dalt. Trans. 2015, 44, 17883–17905. (20) Lai, K.; Wang, B.; Zhang, Y.; Zhang, Y. High Pressure Effect on Phase Transition Behavior of Lipid Bilayers. Phys. Chem. Chem. Phys. 2012, 14, 5744–5752. (21) Teng, Z.; Zheng, G.; Dou, Y.; Li, W.; Mou, C. Y.; Zhang, X.; Asiri, A. M.; Zhao, D. Highly Ordered Mesoporous Silica Films with Perpendicular Mesochannels by a Simple Stober-Solution Growth Approach. Angew. Chem., Int. Ed. 2012, 51, 2173–2177. (22) Feng, M.; You, W.; Wu, Z.; Chen, Q.; Zhan, H. Mildly Alkaline Preparation and Methylene Blue Adsorption Capacity of Hierarchical Flower-like Sodium Titanate. ACS Appl. Mater. Interfaces 2013, 5, 12654–12662. (23) Koley, P.; Pramanik, A. Multilayer Vesicles, Tubes, Various Porous Structures and Organo Gels through the Solvent-Assisted Self-Assembly of Two Modified Tripeptides and Their Different Applications. Soft Matter 2012, 8, 5364–5374. (24) Koley, P.; Sakurai, M.; Aono, M. Controlled Fabrication of Silk Protein Sericin Mediated Hierarchical Hybrid Flowers and Their Excellent Adsorption Capability of Heavy Metal Ions of Pb(II), Cd(II) and Hg(II). ACS Appl. Mater. Interfaces 2016, 8, 2380–2392. (25) Tan, L. F.; Chen, D.; Liu, H. Y.; Tang, F. Q. A Silica Nanorattle with a Mesoporous Shell: An Ideal Nanoreactor for the Preparation of Tunable Gold Cores. Adv. Mater. 2010, 22, 4885– 4889. (26) Ji, T.; Chen, L.; Schmitz, M.; Bao, F. S.; Zhu, J. Hierarchical Macrotube/mesopore Carbon Decorated with Mono-Dispersed Ag Nanoparticles as a Highly Active Catalyst. Green Chem.


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 17

2015, 17, 2515–2523. (27) Meng, X.; Li, B.; Ren, X.; Tan, L.; Huang, Z.; Tang, F. One-Pot Gradient Solvothermal Synthesis of Au–Fe3O4 Hybrid Nanoparticles for Magnetically Recyclable Catalytic Applications. J. Mater. Chem. A 2013, 1, 10513–10517. (28) Manzano, M.; Vallet-Regí, M. New Developments in Ordered Mesoporous Materials for Drug Delivery. J. Mater. Chem. 2010, 20, 5593–5604. (29) Ehlert, N.; Mueller, P. P.; Stieve, M.; Lenarz, T.; Behrens, P. Mesoporous Silica Films as a Novel Biomaterial: Applications in the Middle Ear. Chem. Soc. Rev. 2013, 42, 3847–3861. (30) Xu, R.; Zhang, G.; Mai, J.; Deng, X.; Segura-Ibarra, V.; Wu, S.; Shen, J.; Liu, H.; Hu, Z.; Chen, L.; Huang, Y.; Koay, E.; Huang, Y.; Liu, J.; Ensor, J. E.; Blanco, E.; Liu, X.; Ferrari, M.; Shen, H. An Injectable Nanoparticle Generator Enhances Delivery of Cancer Therapeutics. Nat. Biotechnol. 2016, 34, 414–418.


16

Page 17 of 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


Table of Contents

Hierarchical Lotus Leaf-like Mesoporous Silica Material with Unique Bilayer and Hollow Sandwich-like Folds: Synthesis, Mechanism, and Applications

Nanjing Hao, Hamid T. Chorsi, and John X. J. Zhang*

Synopsis: Lotus leaf-like hierarchical mesoporous silica structure was successfully developed as efficient adsorbent, catalyst supporter and drug carriers.


17

Hierarchical Lotus Leaf-Like Mesoporous Silica Material with Unique

Recommend Documents