Permeability and Micromechanical Properties of Silk Ionomer Microcapsules
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- 作者：Chunhong Ye ; Irina Drachuk ; Rossella Calabrese ; Hongqi Dai ; David L. Kaplan ; Vladimir V. Tsukruk
- 刊名：Langmuir
- 出版年：2012
- 出版时间：August 21, 2012
- 年：2012
- 卷：28
- 期：33
- 页码：12235-12244
- 全文大小：502K
- 年卷期：v.28,no.33(August 21, 2012)
- ISSN：1520-5827
文摘
We studied the pH-responsive behavior of layer-by-layer (LbL) microcapsules fabricated from silk fibroin chemically modified with different poly amino acid side chains: cationic (silk-poly l-lysine, SF-PL) or anionic (silk-poly-l-glutamic acid, SF-PG). We observed that stable ultrathin shell microcapsules can be assembled with a dramatic increase in swelling, thickness, and microroughness at extremely acidic (pH < 2.5) and basic (pH > 11.0) conditions without noticeable disintegration. These changes are accompanied by dramatic changes in shell permeability with a 2 orders of magnitude increase in the diffusion coefficient. Moreover, the silk ionomer shells undergo remarkable softening with a drop in Young鈥檚 modulus by more than 1 order of magnitude due to the swelling, stretching, and increase in material porosity. The ability to control permeability and mechanical properties over a wide range for the silk-based microcapsules, with distinguishing stability under harsh environmental conditions, provides an important system for controlled loading and release and applications in bioengineering.