Karve Kiran A, Gil Eun Seok, McCarthy Stephen P, Kaplan David L
Biomedical Engineering and Biotechnology Program, University of Massachusetts at Lowell, Lowell MA 01854 USA.
J Memb Sci. 2011 Nov 1;383(1-2):44-49. doi: 10.1016/j.memsci.2011.08.032.
The material properties of silk are favorable for drug delivery due to the ability to control material structure and morphology under ambient, aqueous processing conditions. Mass transport of compounds with varying physical-chemical characteristics was studied in silk fibroin films with control of β-sheet crystalline content. Two compounds, vitamin B12 and fluorescein isothiocynate (FITC) labeled lysozyme were studied in a diffusion apparatus to determine transport through silk films. The films exhibited size exclusion phenomenon with permeability coefficients with contrasting trends with increases in β-sheet crystallinity. The size exclusion phenomenon observed with the two model compounds was characterized by contrasting trends in permeability coefficients of the films as a function of β-sheet crystallinity. The diffusivity of the compounds was examined in the context of free volume theory. Apart from the β-sheet crystallinity, size of the compound and its interactions with silk influenced mass transfer. Diffusivity of vitamin B12 was modeled to define a power law relationship with β-sheet crystallinity. The results of the study demonstrate that diffusion of therapeutic agents though silk fibroin films can be directed to match a desired rate by modulating secondary structure of the silk proteins.
由于能够在环境水性加工条件下控制材料结构和形态，丝绸的材料特性有利于药物递送。在控制β-折叠晶体含量的丝素蛋白薄膜中，研究了具有不同物理化学特性的化合物的质量传输。在扩散装置中研究了两种化合物，即维生素B12和异硫氰酸荧光素（FITC）标记的溶菌酶，以确定它们通过丝绸薄膜的传输情况。这些薄膜表现出尺寸排阻现象，其渗透系数随β-折叠结晶度的增加呈现出相反的趋势。观察到的两种模型化合物的尺寸排阻现象的特征是薄膜的渗透系数随β-折叠结晶度的变化呈现出相反的趋势。在自由体积理论的背景下研究了化合物的扩散系数。除了β-折叠结晶度外，化合物的大小及其与丝绸的相互作用也影响传质。对维生素B12的扩散系数进行建模，以定义其与β-折叠结晶度的幂律关系。研究结果表明，通过调节丝绸蛋白的二级结构，可以控制治疗剂通过丝素蛋白薄膜的扩散速率，使其达到所需的速率。
