Charged Nanowire-Directed Growth of Amorphous Calcium

Subscriber access provided by UNIV OF NEW ENGLAND ARMIDALE

Interface-Rich Materials and Assemblies

Charged Nanowire-Directed Growth of Amorphous Calcium Carbonate Nanosheets in a Mixed Solvent for Biomimetic Composite Films Yangyi Liu, Lei Liu, Si-Ming Chen, Fu-Jia Chang, Li-Bo Mao, Huai-Ling Gao, Tao Ma, and Shu-Hong Yu Langmuir, Just Accepted Manuscript • Publication Date (Web): 19 Apr 2018 Downloaded from http://pubs.acs.org on April 19, 2018

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 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 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.

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 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

Langmuir

Charged Nanowire-Directed Growth of Amorphous Calcium Carbonate Nanosheets in a Mixed Solvent for Biomimetic Composite Films ‡

‡

Yang-Yi Liu, Lei Liu, Si-Ming Chen, Fu-Jia Chang, Li-Bo Mao, Huai-Ling Gao, Tao Ma, ShuHong Yu* Division of Nanomaterials and Chemistry, Hefei National Research Center for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China KEYWORDS. biomineralization, inorganic nanowires, amorphous calcium carbonate, nanosheets, nanocomposite films

ACS Paragon Plus Environment

1

Langmuir 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 25

ABSTRACT Bio-inspired mineralization is an effective way for fabricating complicated inorganic materials, which inspires us to develop new methods to synthesize materials with fascinating properties. In this article, we report that the charged tellurium nanowires (TeNWs) can be used as biomacromolecule analogues to direct the formation of amorphous calcium carbonate (ACC) nanosheets (ACCNs) in a mixed solvent. The effects of surface charges and the concentration of the TeNWs on the formation of ACCNs have been investigated. Particularly, the produced ACCNs can be functionalized by Fe3O4 nanoparticles to produce magnetic ACC/Fe3O4 hybrid nanosheets, which can be used to construct ACC/Fe3O4 composite films through a selfevaporation process. Moreover, sodium alginate-ACC nanocomposite films with remarkable toughness and good transmittance can also be fabricated by using such ACCNs as nanoscale building blocks. This mineralization approach in a mixed solvent using charged tellurium nanowires as bio-macromolecule analogues provides a new way for the synthesis of ACCNs, which can be used as nanoscale building blocks for fabrication of biomimetic composite films.

Table Content Used Only


2

Page 3 of 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

Langmuir

INTRODUCTION In biomineralization systems, macromolecules or macromolecule assemblies are thought to present ordered arrays of charged groups, which can induce the oriented nucleation and growth of biominerals.[1,2] These macromolecule matrixes can interact with biominerals to decide their shapes, structures and properties.[3-6] Among them, protein layers (for example β-chitin and lustrins) in nacre are one of the most intensively investigated systems, and they control the growth of lamellar calcium carbonate to form brick-and-mortar structure that is responsible for the remarkable strength and toughness of nacre.[7,8] Thus, such brick-and-mortar structure of nacre has stimulated the research on 2-dimensional materials

[9-11]

and has been mimicked to

fabricate artificial nacre-like nanocomposites by using numerous nanoscale lamellar materials.[1224]

Besides, charged bio-macromolecules also play a significant role in the stabilization of amorphous precursors.[25,26] Recently, it has been reported that aragonite platelets in nacre are covered with a continuous layer of amorphous calcium carbonate (ACC) that results from the macromolecules induced mineralization.[27] ACC, the least stable phase of calcium carbonate, has been found to strengthen the skeleton or as transient precursors to other crystalline phases of CaCO3. [25, 28] Therefore, the research on the preparation and stabilization of ACC structures has attracted much attention in the past few decades.[29] Various additives, such as magnesium ion,[3031]

polypeptides,[32] phosphate,[33] acidic macromolecules,[34] DNA[35] and ATP[36] have been used

to prepare and stabilize ACC.


3

Langmuir 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 25

Recently, it has been illustrated that ultrathin inorganic nanowires (NWs) are analogous to macromolecules or aggregated assemblies of supramolecular polymers due to their high specific surface area.[37-41] Similar to macromolecules, there are abundant charges on the surface of ultrathin NWs. So, inspired by the basic principles of biomineralization, utilizing charged ultrathin NWs to control the nucleation and growth of biominerals turns to be an urgent research issue and various hybrid materials with special performances has also been synthesized by this approach.[42-44] Moreover, we previously found that biomineralization in a mixed solvent system can help us control the polymorph and morphology of minerals through adjusting the thermodynamics and kinetics.[45-49] Recently, we have demonstrated charged inorganic nanowiredirected mineralization of ACC in a mixed solvent of water and N, N-dimethylformamide.[50] However, this concept that using charged NWs as growth inducers to control the mineralization in a mixed solvent has not been applied to the synthesis of ACC nanosheets (ACCNs). Herein, we report that ACCNs can be synthesized in a mixed solvent of water and ethanol by using charged TeNWs as growth inducers. The effects of surface charges and the concentration of the TeNWs stabilized by polyvinyl pyrrolidone (PVP) on the morphology of the products have been investigated. Time-dependent experiments were carried out to illustrate the formation mechanism of ACCNs. Furthermore, Fe3O4 nanoparticles (NPs) can be dispersed on the ACCNs to prepare magnetic ACC/Fe3O4 hybrid nanosheets. By using such ACCNs as nanoscale building blocks and sodium alginate as glue, we can fabricate freestanding sodium alginate-ACC nanocomposite films with remarkable toughness and good transmittance. EXPERIMENTAL SECTION


4

Page 5 of 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

Langmuir

Synthesis of charged ultrathin TeNWs. The TeNWs were synthesized according to our previous report.[51] In a typical synthesis, 1 g of PVP was dissolved into 33 mL of deionized water (DIW) in a Teflon-lined stainless steel autoclave with a volume capacity of 50 mL under vigorous stirring to form a homogeneous solution. After that, 0.0923 g of sodium tellurite was dissolved into the above solution, and then 3.35 mL of aqueous ammonia solution (25-28%, w/w %) and 1.65 mL of hydrazine hydrate (85%, w/w %) were added into the above mixed solution, respectively. When the solution was clear, the vessel was closed and maintained at 180 °C in an oven for 3 h to prepare the initial TeNWs solution. Synthesis of ACCNs. The first step for fabrication ACCNs is precipitation of TeNWs. For a typical precipitation process, 15 mL of acetone was added into 4 mL of the initial TeNWs solution to precipitate the TeNWs, which were collected by centrifugation (8000 rpm, 3 min), rinsed with DIW for one time and then re-dispersed into 4 mL of DIW to obtain TeNWs solution. In a typical fabrication process of ACCNs, 0.440 g of calcium acetate and 0.450 g of urea were dissolving in a 50-mL conical bottle containing 6 mL of DIW and 30 mL of ethanol. Then, previous obtained TeNWs solution (4 mL) was added to the conical bottle under magnetic stirring. Finally, the conical bottle was heated at 80 °C in an oven for 24 h. Preparation of ACC/Fe3O4 hybrid nanosheets and magnetic ACC/Fe3O4 composite films. Firstly, Fe3O4 NPs with a diameter of 4 nm were prepared by a solvethermal route according to a previous report.[52] Typically, 0.5 mmol of Fe(acac)3 was dispersed in a mixed solvent of octylamine (8 mL) and octanol (8 mL) under magnetic stirring. Then, the solution was transferred to a 25 mL Teflon-lined autoclave and maintained at 240 °C for 2 h. The product was washed by ethanol and DIW for 3 times, respectively. Magnetic ACC/Fe3O4 hybrid nanosheets was obtained by direct physical mixing. Briefly, 30 mg of the mixture of ACCNs and Fe3O4 NPs


5

Langmuir 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 25

was dispersed in 100 mL absolute ethanol (the mass ratio of ACCNs to Fe3O4 NPs is 2:1, 1:1 or 1:2). Then, the mixed solution was shaken in an Innova 40 benchtop incubator shaker for 6 h with a rotation rate of 200 rpm. The product was collected by centrifugation and dried in vacuum drying oven. The magnetic ACC/Fe3O4 hybrid films were prepared through a self-evaporation process. Briefly, a desired amount of ACC/Fe3O4 hybrid nanosheets was dispersed in 20 mL of DIW to from homogeneous suspension that was then poured into the Petri dish and kept at room for evaporation to prepare the magnetic composite films. Fabrication of nacre-like sodium alginate-ACC hybrid films. A desired amount of mixture of ACCNs and sodium alginate was dispersed in 20 mL of DIW to form uniform glue. Then the obtained suspension was poured into the Petri dish and kept at room temperature for evaporation to form sodium alginate-ACC hybrid films. Finally, the freestanding films were peeled off from the bottom of the Petri dish. Characterization. The crystalline phase of the products were identified by X-ray diffraction (XRD) using a Philips X’ Pert Pro Super diffractometer with Cu Kα (λ = 1.54056 Å) and Fourier transform infrared (FT-IR) spectra measured on a Bruker Vector-22 FT-IR spectrometer from 4000 to 400 cm-1 at room temperature. Scanning electron microscope (SEM) images were taken on a field-emission scanning electron microanalyzer (Zeiss SUPRA 40). Transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive X-Ray (EDX) spectroscopy was performed on Talos F200X with an acceleration voltage of 200 kV. Atomic force microscope (AFM) images were taken by Vecco di Innva. A freshly cleaved mica slides were used as substrates and the samples were diluted and dropped on the substrate for further AFM measurement. The magnetic properties of the samples were characterized by a superconducting quantum interface device magnetometer (Quantum Design


6

Page 7 of 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

Langmuir

MPMS XL). The measurement for the mechanical properties of freestanding films was carried out under tensile mode in Instron 5565A mechanical testing machine. For the mechanical testing, the films were cut into rectangle bars of approximate width 5 mm and length 20 mm with a razor blade. The distance between two clamps was 5 mm and the load speed was 10 mm min-1. RESULT AND DISCUSSION

Figure 1. The SEM (a, b), TEM (c) and HRTEM (d) images of ACCNs prepared after mineralization for 24 h in mixed solvent mineralization system by using TeNWs as growth inducers. (e) The TEM image of a single ACCN and corresponding EDX elemental mapping images for Ca and Te signals (Ca, pink; Te, green). The charged ultrathin TeNWs induced mineralization process of ACC was carried out in TeNWs dispersed water/ethanol mixed solution. The XRD pattern analysis (See Supporting Information, Figure S1a) shows that the product is amorphous because no diffraction peaks can be detected. The two broad humps located at 2θ values of approximately 33 degree and 46 degree in the XRD pattern are characteristics of ACC. The SEM and TEM images of the products illustrate that the uniform nanosheets can be obtained after mineralization for 24 h (Figures 1ac). The thickness of the nanosheets characterized by atomic force microscopy (AFM) is ~ 15 nm


7

Langmuir 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 25

(Figure S2c). The HRTEM image further confirms the amorphous essence because any lattice spacing cannot be detected, as shown in Figure 1d. FT-IR spectrum confirms that the product is amorphous calcium carbonate and the presence of PVP molecules on the surface of ACCNs (Figure S1c). The peak at 873 cm-1 is attributed to the carbonate out-of-plane bending absorption, the symmetric stretch at 1076 cm-1 broadens and the asymmetric stretch splits into two parts at around 1424 and 1485 cm-1, which is consistent with the typical spectra of ACC.[30] Furthermore, it can be clearly seen that C-H attributes a stretching vibration peak at 2960 cm-1, C=O attributes a stretching vibration peak at 1630 cm-1, and stretching vibration peaks at 1424 cm-1 are mainly caused by C-H, which is consistent with the typical FT-IR spectrum of PVP.[53] The EDX spectroscopy (Figure S1b) and corresponding element mapping images (Figure 1e) illustrate that Ca and Te elements are homogeneously distributed throughout the whole ACCN. In order to study the effect of the charges around TeNWs on the final structure of the product, we performed a series of experiments that using TeNWs with different charge density tuned by washing with water to induce the nucleation and growth of CaCO3. When initial TeNWs solution was used as growth inducers, both some aggregates constructed by nanosheets and the aggregates of TeNWs coated by ACC NPs were found in the products (Figure 2a). When using precipitated TeNWs washed with DIW for two times as inducers, the prepared nanosheets are curlier than that synthesized with precipitated TeNWs washed for only one time (Figure 2b). Continuing to increase the washing frequency, the obtained nanosheets are much curlier (Figure 2c).


8

Page 9 of 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

Langmuir

Figure 2. The SEM images of the samples prepared after mineralization for 24 hours in mixed solvent mineralization system when use (a) initial solution of TeNWs, precipitated TeNWs washed with water for two times (b) and three times (c), respectively. The surface charge density can uncover the influence of the surface charges of TeNWs on the mineralization. Our previous work have illustrated that washing TeNWs with water can reduce the surface charges of TeNWs caused by adsorbed PVP molecules.

[44]

When using initial

TeNWs solution as solvent and inducers, large amount of PVP molecules dispersed in the solvent could also adsorb Ca(II) ions, resulting in the complicated products. When TeNWs washed with DIW for only one time were used as inducers, PVP molecules in solvent were removed and Ca(II) ions could only be adsorbed on the surface of TeNWs before the mineralization process (Figure S5), and accordingly homogeneous ACCNs can be obtained. Increasing the frequency of washing to two times, the surface charge of TeNWs continued to decrease, nucleation sites for ACC on the surface of TeNWs reduced, and thus more TeNWs were needed to form a single nanosheet, which may lead to the bending of ACCNs. When increasing the washing frequency of TeNWs to three times, the obtained ACCNs are much curlier than that obtained when TeNWs washed for two times. Thus, tuning the surface charges of TeNWs by washing with water plays a key role in the formation of the nanosheets with different morphology.


9

Langmuir

(d)

Intensity (a.u.)

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 25

(c)

(b) (a)

20

30

40

50

60

2θ (degree)

Figure 3. XRD patterns of the samples prepared after 24 h in mixed solvent mineralization system with different concentration of TeNWs: (a) 0 ; (b) 0.2 mM; (c) 1.1 mM; (d) 3.8 mM. The blue, orange and pink lines highlight the diffraction peaks of vaterites (JCPDF No. 33-0268), aragonites (JCPDF No.41-1475) and TeNWs (JCPDF No.36-1452), respectively. Specially, the concentration of TeNWs on the phase and morphology of the final products have also been explored (Figure 3 and Figure S3). In the absence of TeNWs, dumbbell-like aragonites were obtained (Figure 3a and Figure S3a). When the concentration of TeNWs was 0.2 mM, some nanosheets could be observed from the SEM image, however, the dumbbell-like aragonites were still the main products (Figure 3b and Figure S3b). Apart from that, vaterite phase was also found from the XRD pattern (Figure 3b). Further increasing the concentration of TeNWs to 1.1 mM, the main products turned to be ACCNs (Figures 3c and S3c). When the concentration of TeNWs was 1.5 mM, the products were consisted of ACCNs (Figures 1a, b and Figure S1a). Furthermore, it was found that continuously increasing the concentration of TeNWs, the composition of the final products did not change (Figure 3d and Figure S3d). Interestingly, the vaterite phase disappeared gradually with increasing the concentration of TeNWs (Figures 3b-d). All the data mentioned above illustrated that TeNWs can induce the formation of ACCNs and hinder ACC from crystallization in the present mineralization system.


10

Page 11 of 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

Langmuir

Figure 4. SEM (a, c, e) and TEM (b, d, f) images of the samples prepared in mixed solvent mineralization system controlled by charged TeNWs after different reaction time: (a, d) 1 h; (b, e) 6 h; (c, f) 24 h. The insets show digital photos of the corresponding samples. To explore the formation mechanism of ACCNs, the time-dependent evolution process has been investigated (Figure 4, Figure S2 and Figure S7). Before the mineralization process, Ca(II) ions can adsorb on the surface of TeNWs by interaction with PVP molecules (Figure S4). In the initial two hours for mineralization, 2-demensional frameworks were found, and large amount of TeNWs on the surface of frameworks could also be found (Figure 4a, Figure S2a and Figure S7a). Along with the reaction time prolonging to 6 h, TeNWs were hardly observed from SEM images (Figure 4b), while a few pores could be observed from TEM and AFM images, as shown in Figure 4e and Figure S2b, which indicates that the majority of TeNWs were covered by ACC gradually. As the mineralization went on, the morphology of the products did not change obviously (Figure S7b, c). With increasing the reaction time to 24 h, the color of the products turned to be white, the TeNWs were hard to be observed on the surface of product(Figures 4c, f), and meanwhile the area of the nanosheets became larger (Figure S2c).


11

Langmuir 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 25

To further illustrate that the TeNWs were coated by ACC during the mineralization process, other experiments were also conducted. Firstly, we mixed ACC solution with TeNWs solution directly. As shown in Figure S5, the color of the mixed solution was black blue, which was different from the color of ACCNs solution obtained by the TeNWs induced mineralization process, which confirms that TeNWs were coated by ACC. Additionally, when no Ca resource was added into the mineralization system, the color of reaction solution could nearly keep consistent during the whole process (Figure S6). It indicates that TeNWs cannot be oxidized or etched completely during the biomineralization process.[54] Thus, these results confirmed that TeNWs were coated by ACC instead of being etched during the mineralization process. However, it must be pointed that the detailed formation mechanism of the ACCNs induced by TeNWs is rather complicated and needs more work in the future.


12

Page 13 of 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

Langmuir

Figure 5. The digital photographs of a typical as-prepared ACC/Fe3O4 composite films (a, b) and the composite films could be actuated by a household magnet (c). (d - f) TEM images of ACC/Fe3O4 hybrid nanosheets prepared by controlling the mass ratio of ACCNs to Fe3O4 NPs at 2:1 (d), 1:1 (e), 1:2 (f) respectively. The TEM (g) and corresponding EDX elemental mapping images (h) for Fe, Te and Ca signals of the ACCNs decorated with Fe3O4 NPs (the mass ratio of ACCNs to Fe3O4 NPs is 1:1). (i) The HRTEM images of ACCNs decorated by Fe3O4 NPs (the mass ratio of ACCNs to Fe3O4 NPs is 1:1). (j) The representative XRD pattern of ACC/Fe3O4 hybrid nanosheets (the mass ratio of ACCNs to Fe3O4 NPs is 1:1). (k) Room-temperature magnetic hysteresis loops of the three representative ACC- Fe3O4 composite nanosheets samples. The ACC-Fe3O4-1, the ACC-Fe3O4-2 and the ACC-Fe3O4-3 corresponding to the samples prepared with the initial mass ratio of ACCNs to Fe3O4 NPs at 2:1, 1:1, 1:2, respectively. Such ACCNs can be decorated with magnetic Fe3O4 NPs on their surface and then can be further used for constructing a free-standing magnetic hybrid film through a self-evaporation process (Figures 5a-c). The ACC/Fe3O4 hybrid nanosheets can be prepared by direct mixing


13

Langmuir 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 25

Fe3O4 NPs with ACCNs. From Figures 5d and 5e, we can clearly see that the magnetite NPs with a diameter of ~ 4 nm were dispersed on the surface of ACCNs uniformly. When the mass ratio of ACCNs to Fe3O4 NPs is 1:2, Fe3O4 NPs aggregates were observed (Figure 5c). In this situation, the loading was saturated. Conclusively, the coverage density of Fe3O4 NPs on the surface of ACCNs can be easily tuned by altering the initial weight ratio of ACCNs to Fe3O4 NPs. The EDX elemental mapping images illustrate that the magnetite nanoparticles are distributed on the ACCNs uniformly (Figures 5g and 5h). The HRTEM image (Figure 5i) further reveals the detailed distribution of Fe3O4 NPs on the surface of ACCNs. The representative lattice fringe spaces between two adjacent crystal planes of particles were determined to 2.034 Å and 1.693 Å, corresponding to the (400) and the (422) lattice planes of a cubic Fe3O4, respectively. The XRD pattern (Figure 5j) can be indexed as a pure crystal structure of magnetite (JCPDF card No. 190629). The broadening diffraction peaks with high intensity indicate that the Fe3O4 NPs are small and highly crystalline. Magnetic measurements were conducted on three kinds of representative ACC/Fe3O4 hybrid nanosheets with different mass ratio of ACCNs to Fe3O4 NPs, as shown in Figure 5k. The magnetic curves show that all of the samples with different loading amount of Fe3O4 NPs exhibited superparamagnetic behaviour at room temperature without coercivity and remanence, which are consistent with the size of Fe3O4 NPs in the superparamagnetic size range (Figures 5ac). The saturation magnetizations of the three samples were 5.5, 9.7 and 10.7 emug-1, corresponding to the samples with the mass ratio of ACCNs to Fe3O4 NPs at 2:1, 1:1 and 1:2 respectively. These results illustrate that the magnetic properties of ACC/Fe3O4 hybrid nanosheets can be tuned by controlling the mass ratio of ACCNs to Fe3O4 NPs.


14

Page 15 of 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

Langmuir

Figure 6. (a, b) Cross-sectional SEM image and high magnification SEM image of a typical sodium alginate-ACCN composite film fabricated by self-evaporation process. (c) Tensile strength-strain curves for sodium alginate-ACCN composite films. (d) UV/Vis transmittance spectra of different composite films prepared with different mass ratio of sodium alginate to ACCNs. (e) Photographs of different composite films prepared with different mass ratio of sodium alginate to ACCNs. Inset in (a) shows the photograph of corresponding flexible composite film. The above prepared ACCNs were further fabricated into nacre-like sodium alginate-ACC nanocomposite films. Freestanding films with different mass ratio of sodium alginate to ACCNs were prepared by self-evaporation process (in such process PVP on the surface of ACCNs can stabilize the ACCNs,[23] Figures S8a and S8c). The thickness of the films can be tailored by controlling the volume of the sodium alginate-ACCNs suspension. The cross-sectional SEM images of sodium alginate-ACC hybrid films are shown in Figure 6a and 6b. The sodium alginate-ACCN hybrid building blocks stacked together densely to form oriented lamellar


15

Langmuir 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 25

microstructures. Small angle XRD pattern illustrates that the thinnest well-defined structure is about 2.44 nm (Figures S8b and S8d). Furthermore, the high orientation of the building blocks in sodium alginate-ACC hybrid films leads to a good transmittance (Figures 6d and 6e). For example, the transmission spectra show about 70-90% transparence across the visible spectrum of light for the film with 10 wt% ACCNs, in contrast to 55-80% for the absolute sodium alginate film (Figure 6d). Tensile-strain mechanical measurement was carried out to illustrate the role of the nacre-like structures play on the mechanical properties. The largest tensile stress is 76±5.5 MPa, obtained from the film with 10 wt% ACCNs (Figure 6c and Table 1), which is comparable to that of nacre (from 80 to 130 MPa).[55] Generally, the tensile strain decreased with the increasing content of ACCNs, the largest strain was found to be 74.2±7.3% for the film of 7.5 wt% ACCNs and the least was found to be 45.0±4.5% for the films of 20 wt% ACCNs. These data illustrate that our nacreous films have a higher energy absorption capacity and a better crack resistance. The largest Young’s modulus is 1.1±0.7 GPa for the films with 20 wt% ACCNs, which means that the composite films are soft but have a high elasticity. Table 1. Summary of the mechanical properties of films tested by tensile testing.

Ultimate stress [MPa]

Samples

Ultimate strain [%]

Young’s Modulus [MPa]

Absolute sodium alginate

49.2±6.4

64.3±5.1

600.9±115.9

5 wt% ACCN + 95 wt% sodium alginate

64.6±4.2

71.0±10.2

679.8±91.5

7.5 wt% ACCN + 92.5 wt% sodium alginate

64.8±6.0

74.2±7.3

815.4±69.0


75.8±5.5

71.0±5.6

983.9±107.3


16

Page 17 of 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

Langmuir

12.5 wt% ACCN + 87.5 wt% sodium alginate

59.6±4.0

64.1±10.5

791.2±90.5


52.1±2.9

57.7±6.1

813.6±79.0


53.7±3.9

45.0±4.5

1163.9±71.4

The mechanical properties can be explained by the coordination interaction between Ca ions and alginate. The Ca ions on the surface of the ACCNs can bind to carboxylate groups on the chain of sodium alginate to form dimers, in which Ca ions were wrapped by alginate chains. Such structures were explained as “egg-box model”.[56,57] When in tension, the chains can be straightened out and sustain higher energy-absorption capacity. Moreover, the coordination interaction between Ca ions and alginate can also increase the strength of the films. CONCLUSION In summary, we have prepared ACCNs by using charged TeNWs as growth inducers in a mixed solvent system. The effect of the surface charges and the concentration of the TeNWs stabilized by PVP on the morphology of the mineralization products has been discussed. Time-dependent experiments were performed to illustrate the formation mechanism of ACCNs. We also demonstrated that the ACCNs can be for the construction of macroscopic functional composite films. Such unique ACCNs can be magnetized by direct mixing magnetic Fe3O4 NPs with ACCNs to produce ACC/Fe3O4 hybrid nanosheets, which can be easily assembled into selfstanding and flexible magnetic films through a casting process. Furthermore, sodium alginateACC nanocomposite films with tunable composition and mechanical properties can be for constructed by using ACCNs as nanoscale building blocks and sodium alginate as glue. This straightforward solution synthetic route under mild conditions provides a new way for the


17

Langmuir 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 25

synthesis of ACCNs, which can be used as nanoscale building blocks for fabrication of biomimetic composite films. ASSOCIATED CONTENT Supporting Information. The following files are available free of charge. Supplementary data and summary (PDF) AUTHOR INFORMATION Corresponding Author *Fax: +86 551 63603040. E-mail: [email protected] Author Contributions ‡

These authors contributed equally.

Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (Grants 21761132008, 51732011), the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant 21521001), Key Research Program of Frontier Sciences, CAS (Grant QYZDJ-SSW-SLH036), the National Basic Research Program of China (Grant 2014CB931800), the Users with Excellence and Scientific Research Grant of Hefei Science Center of CAS (2015HSC-UE007). This work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication. REFERENCES


18

Page 19 of 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

Langmuir

(1)

Nudelman, F.; Chen, H. H.; Goldberg, H. A.; Weiner, S.; Addadi, L., Spiers Memorial

Lecture: Lessons from Biomineralization: Comparing the Growth Strategies of Mollusc Shell Prismatic and Nacreous Layers in Atrina Rigida. Faraday Discuss. 2007, 136, 9-25. (2)

Smeets, P. J. M.; Cho, K. R.; Kempen, R. G. E.; Sommerdijk, N. A. J. M.; De Yoreo, J.

J., Calcium Carbonate Nucleation Driven by Ion Binding in a Biomimetic Matrix Revealed by in Situ Electron Microscopy. Nat. Mater. 2015, 14, 394-399. (3)

Weiner, S.; Addadi, L., Crystallization Pathways in Biomineralization. Annu. Rev. Mater.

Res. 2011, 41, 21-40. (4)

Yao, S.; Jin, B.; Liu, Z.; Shao, C.; Zhao, R.; Wang, X.; Tang, R., Biomineralization:

From Material Tactics to Biological Strategy. Adv. Mater. 2017, 29, 1605903. (5)

Schenk, A. S.; Cantaert, B.; Kim, Y.-Y.; Li, Y.; Read, E. S.; Semsarilar, M.; Armes, S.

P.; Meldrum, F. C., Systematic Study of the Effects of Polyamines on Calcium Carbonate Precipitation. Chem. Mater. 2014, 26, 2703-2711. (6)

Wegst, U. G. K.; Bai, H.; Saiz, E.; Tomsia, A. P.; Ritchie, R. O., Bioinspired Structural

Materials. Nat. Mater. 2015, 14, 23-36. (7)

Sellinger, A.; Weiss, P. M.; Nguyen, A.; Lu, Y.; Assink, R. A.; Gong, W.; Brinker, C. J.,

Continuous Self-Assembly of Organic-Inorganic Nanocomposite Coatings that Mimic Nacre. Nature 1998, 394, 256-260. (8)

Tang, Z.; Kotov, N. A.; Magonov, S.; Ozturk, B., Nanostructured Artificial Nacre. Nat.

Mater. 2003, 2, 413-418. (9)

Zhao, Y.; Jia, X.; Waterhouse Geoffrey, I. N.; Wu, L. Z.; Tung, C. H.; O'Hare, D.;

Zhang, T. Layered Double Hydroxide Nanostructured Photocatalysts for Renewable Energy Production. Adv. Energy Mater. 2015, 6, 1501974.


19

Langmuir 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 25

(10) Yu, H.; Shi, R.; Zhao, Y.; Bian, T.; Zhao, Y.; Zhou, C.; Waterhouse Geoffrey, I. N.; Wu, L. Z.; Tung, C. H.; Zhang, T. Alkali‐Assisted Synthesis of Nitrogen Deficient Graphitic Carbon Nitride with Tunable Band Structures for Efficient Visible‐Light‐Driven Hydrogen Evolution. Adv. Mater. 2017, 29, 1605148. (11) Liu, P.; Xiang, B. 2D Hetero-Structures Based on Transition Metal Dichalcogenides: Fabrication, Properties and Applications. Sci. Bull.2017, 62, 1148-1161. (12) Yao, H.-B.; Fang, H.-Y.; Wang, X.-H.; Yu, S.-H., Hierarchical Assembly of Micro/Nano-Building Blocks: Bio-Inspired Rigid Structural Functional Materials. Chem. Soc. Rev. 2011, 40, 3764-3785. (13) Kim, S.; Park, C. B., Bio-Inspired Synthesis of Minerals for Energy, Environment, and Medicinal Applications. Adv. Funct. Mater. 2013, 23, 10-25. (14) Egan, P.; Sinko, R.; LeDuc, P. R.; Keten, S., The Role of Mechanics in Biological and Bio-Inspired systems. Nat. Commun. 2015, 6, 7418. (15) Mao, L.-B.; Gao, H.-L.; Yao, H.-B.; Liu, L.; Cölfen, H.; Liu, G.; Chen, S.-M.; Li, S.-K.; Yan, Y.-X.; Liu, Y.-Y.; Yu, S.-H., Synthetic Nacre by Predesigned Matrix-Directed Mineralization. Science 2016, 354, 107-110. (16) Wang, J.; Cheng, Q.; Tang, Z., Layered Nanocomposites Inspired by the Structure and Mechanical Properties of Nacre. Chem. Soc. Rev. 2012, 41, 1111-1129. (17) Aksay, I. A.; Trau, M.; Manne, S.; Honma, I.; Yao, N.; Zhou, L.; Fenter, P.; Eisenberger, P. M.; Gruner, S. M., Biomimetic Pathways for Assembling Inorganic Thin Films. Science 1996, 273, 892-898.


20

Page 21 of 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

Langmuir

(18) Volkmer, D.; Harms, M.; Gower, L.; Ziegler, A., Morphosynthesis of Nacre-Type Laminated CaCO3 Thin Films and Coatings. Angew. Chem. Int. Ed. 2005, 44, 639-644. (19) Kato, T., Polymer/Calcium Carbonate Layered Thin-Film Composites. Adv. Mater. 2000, 12, 1543-1546. (20) Xu, G.; Yao, N.; Aksay, I. A.; Groves, J. T., Biomimetic Synthesis of Macroscopic-Scale Calcium Carbonate Thin Films. Evidence for a Multistep Assembly Process. J. Am. Chem. Soc. 1998, 120, 11977-11985. (21) Zhong, C.; Chu, C. C., Acid Polysaccharide-Induced Amorphous Calcium Carbonate (ACC) Films: Colloidal Nanoparticle Self-Organization Process. Langmuir 2009, 25, 3045-3049. (22) Gower, L. B.; Odom, D. J., Deposition of Calcium Carbonate Films by a PolymerInduced Liquid-Precursor (PILP) Process. J. Cryst. Growth 2000, 210, 719-734. (23) Finnemore, A.; Cunha, P.; Shean, T.; Vignolini, S.; Guldin, S.; Oyen, M.; Steiner, U., Biomimetic Layer-by-Layer Assembly of Artificial Nacre. Nat. Commun. 2012, 3, 966. (24) Li, X. Q.; Zeng, H. C., Calcium Carbonate Nanotablets: Bridging Artificial to Natural Nacre. Adv. Mater. 2012, 24, 6277-6282. (25) Addadi, L.; Raz, S.; Weiner, S., Taking Advantage of Disorder: Amorphous Calcium Carbonate and its Roles in Biomineralization. Adv. Mater. 2003, 15, 959-970. (26) Olszta, M. J.; Cheng, X.; Jee, S. S.; Kumar, R.; Kim, Y.-Y.; Kaufman, M. J.; Douglas, E. P.; Gower, L. B., Bone Structure and Formation: A New Perspective. Mater. Sci. Eng. R 2007, 58, 77-116. (27) Nassif, N.; Pinna, N.; Gehrke, N.; Antonietti, M.; Jäger, C.; Cölfen, H., Amorphous Layer around Aragonite Platelets in Nacre. Proc. Natl. Acad. Sci. U. S. A. 2005, 102, 1265312655.


21

Langmuir 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 25

(28) Cartwright, J. H. E.; Checa, A. G.; Gale, J. D.; Gebauer, D.; Sainz-Díaz, C. I., Calcium Carbonate Polyamorphism and its Role in Biomineralization: How Many Amorphous Calcium Carbonates are there? Angew. Chem. Int. Ed. 2012, 51, 11960-11970. (29) Xiao, J.; Yang, S., Bio-Inspired Synthesis: Understanding and Exploitation of the Cystallization Process from Amorphous Precursors. Nanoscale 2012, 4, 54-65. (30) Jiang, J.; Gao, M.-R.; Qiu, Y.-H.; Yu, S.-H., Gram-Scale, Low-Cost, Rapid Synthesis of Highly Stable Mg-ACC Nanoparticles and their Long-Term Preservation. Nanoscale 2010, 2, 2358-2361. (31) Nishino, Y.; Oaki, Y.; Imai, H., Magnesium-Mediated Nanocrystalline Mosaics of Calcite. Cryst. Growth Des. 2008, 9, 223-226. (32) Dai, L.; Cheng, X.; Gower, L. B., Transition Bars during Transformation of an Amorphous Calcium Carbonate Precursor. Chem. Mater. 2008, 20, 6917-6928. (33) Günther, C.; Becker, A.; Wolf, G.; Epple, M., In Vitro Synthesis and Structural Characterization of Amorphous Calcium Carbonate. Z Anorg. Allg. Chem. 2005, 631, 28302835. (34) Tugulu, S.; Harms, M.; Fricke, M.; Volkmer, D.; Klok, H.-A., Polymer Brushes as Ionotropic Matrices for the Directed Fabrication of Microstructured Calcite Thin Films. Angew. Chem. Int. Ed. 2006, 45, 7458-7461. (35) Sommerdijk, N. A. J. M.; Leeuwen, E. N. M. v.; Vos, M. R. J.; Jansen, J. A., Calcium Carbonate Thin Films as Biomaterial Coatings Using DNA as Crystallization Inhibitor. CrystEngComm 2007, 9, 1209-1214.


22

Page 23 of 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

Langmuir

(36) Qi, C.; Zhu, Y.-J.; Lu, B.-Q.; Zhao, X.-Y.; Zhao, J.; Chen, F.; Wu, J., ATP-Stabilized Amorphous Calcium Carbonate Nanospheres and their Application in Protein Adsorption. Small 2014, 10, 2047-2056. (37) Hu, S.; Wang, X., Ultrathin Nanostructures: Smaller Size with New Phenomena. Chem. Soc. Rev. 2013, 42, 5577-5594. (38) Hu, S.; Liu, H.; Wang, P.; Wang, X., Inorganic Nanostructures with Sizes down to 1 nm: A Macromolecule Analogue. J. Am. Chem. Soc. 2013, 135, 11115-11124. (39) Cademartiri, L.; Scotognella, F.; O’Brien, P. G.; Lotsch, B. V.; Thomson, J.; Petrov, S.; Kherani, N. P.; Ozin, G. A., Cross-Linking Bi2S3 Ultrathin Nanowires: A Platform for Nanostructure Formation and Biomolecule Detection. Nano Lett. 2009, 9, 1482-1486. (40) Huo, Z.; Tsung, C.-k.; Huang, W.; Zhang, X.; Yang, P., Sub-Two Nanometer Single Crystal Au Nanowires. Nano Lett. 2008, 8, 2041-2044. (41) Shaw, S.; Cademartiri, L., Nanowires and Nanostructures that Grow Like Polymer Molecules. Adv. Mater. 2013, 25, 4829-4844. (42) Kim, S.; Ku, S. H.; Lim, S. Y.; Kim, J. H.; Park, C. B., Graphene–Biomineral Hybrid Materials. Adv. Mater. 2011, 23, 2009-2014. (43) Kowalczyk, B.; Bishop, K. J. M.; Lagzi, I.; Wang, D.; Wei, Y.; Han, S.; Grzybowski, B. A., Charged Nanoparticles as Supramolecular Surfactants for Controlling the Growth and Stability of Microcrystals. Nat. Mater. 2012, 11, 227-232. (44) Liang, Y.; Li, Y.; Wang, H.; Zhou, J.; Wang, J.; Regier, T.; Dai, H., Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction. Nat. Mater. 2011, 10, 780-786.


23

Langmuir 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 25

(45) Guo, X.-H.; Yu, S.-H.; Cai, G.-B., Crystallization in a Mixture of Solvents by Using a Crystal Modifier: Morphology Control in the Synthesis of Highly Monodisperse CaCO3 Microspheres. Angew. Chem. Int. Ed. 2006, 45, 3977-3981. (46) Chen, S.-F.; Zhu, J.-H.; Jiang, J.; Cai, G.-B.; Yu, S.-H., Polymer-Controlled Crystallization of Unique Mineral Superstructures. Adv. Mater. 2010, 22, 540-545. (47) Liu, Y.-Y.; Jiang, J.; Gao, M.-R.; Yu, B.; Mao, L.-B.; Yu, S.-H., Phase Transformation of Magnesium Amorphous Calcium Carbonate (Mg-ACC) in a Binary Solution of Ethanol and Water. Cryst. Growth Des. 2013, 13, 59-65. (48) Geng, X.; Liu, L.; Jiang, J.; Yu, S.-H., Crystallization of CaCO3 Mesocrystals and Complex Aggregates in a Mixed Solvent Media Using Polystyrene Sulfonate as a Crystal Growth Modifier. Cryst. Growth Des. 2010, 10, 3448-3453. (49) Chen, S.-F.; Yu, S.-H.; Jiang, J.; Li, F.; Liu, Y., Polymorph Discrimination of CaCO3 Mineral in an Ethanol/Water Solution: Formation of Complex Vaterite Superstructures and Aragonite Rods. Chem. Mater. 2006, 18, 115-122. (50) Liu, Y.-Y.; Liu, L.; Xue, L.; Mao, L.-B.; Gao, H.-L.; Xu, L.; Yu, S.-H., Charged Inorganic Nanowire-Directed Mineralization of Amorphous Calcium Carbonate. ChemNanoMat 2016, 2, 259-263. (51) Qian, H.-S.; Yu, S.-H.; Gong, J.-Y.; Luo, L.-B.; Fei, L.-F., High-Quality Luminescent Tellurium Nanowires of Several Nanometers in Diameter and High Aspect Ratio Synthesized by a Poly (Vinyl Pyrrolidone)-Assisted Hydrothermal Process. Langmuir 2006, 22, 3830-3835. (52) Tian, Y.; Yu, B.; Li, X.; Li, K., Facile Solvothermal Synthesis of Monodisperse Fe3O4 Nanocrystals with Precise Size Control of One Nanometre as Potential MRI Contrast Agents. J. Mater. Chem. 2011, 21, 2476-2481.


24

Page 25 of 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

Langmuir

(53) Couto, G. G.; Klein, J. J.; Schreiner, W. H.; Mosca, D. H.; de Oliveira, A. J. A.; Zarbin, A. J. G., Nickel Nanoparticles Obtained by a Modified Polyol Process: Synthesis, Characterization, and Magnetic Properties. J. Colloid Interface Sci. 2007, 311, 461-468. (54) Xu, L.; Liang, H.-W.; Li, H.-H.; Wang, K.; Yang, Y.; Song, L.-T.; Wang, X.; Yu, S.-H. Understanding the Stability and Reactivity of Ultrathin Tellurium Nanowires in Solution: An Emerging Platform for Chemical Transformation and Material Design. Nano Res. 2015, 8, 10811097. (55) Barthelat, F.; Tang, H.; Zavattieri, P. D.; Li, C. M.; Espinosa, H. D., On the Mechanics of Mother-of-Pearl: A Key Feature in the Material Hierarchical Structure. J. Mech. Phys. Solids 2007, 55, 306-337. (56) Grant, G. T.; Morris, E. R.; Rees, D. A.; Smith, P. J. C.; Thom, D., Biological Interactions between Polysaccharides and Divalent Cations: The Egg-Box Model. FEBS Lett. 1973, 32, 195-198. (57) Morris, E. R.; Rees, D. A.; Thom, D.; Boyd, J., Chiroptical and Stoichiometric Evidence of a Specific, Primary Dimerisation Process in Alginate Gelation. Carbohydr. Res. 1978, 66, 145-154.


25

Charged Nanowire-Directed Growth of Amorphous Calcium

Recommend Documents