Espinosa-Dzib Alejandra, Chen Jun, Zavgorodnya Oleksandra, Kozlovskaya Veronika, Liang Xing, Kharlampieva Eugenia
Department of Chemistry, Center of Nanoscale Materials and Biointegration, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Soft Matter. 2015 Jul 7;11(25):5133-45. doi: 10.1039/c5sm00464k.
We report on enzymatically degradable nanothin coatings obtained by layer-by-layer (LbL) assembly of silk fibroin with poly(N-vinylcaprolactam) (PVCL) via hydrogen bonding and hydrophobic interactions. We found that both silk β-sheet content, controlled through dipping and spin-assisted LbL, and PVCL molecular weight regulate film thickness, microstructure, pH-stability, and biodegradability with a nanoscale precision. Thickness of (silk/PVCL) films increased with increase in PVCL molecular weight and decrease in deposition pH. The impact of assembly pH on film growth was more dramatic for dipped films. These systems show a significant rise in thickness with increase in PVCL molecular weight at pH < 5 but become independent on polymer chain length at pH ≥ 5. We also found that spin-assisted films exhibited a greater stability at elevated pH and against enzymatic degradation as compared to their dipped counterparts. For both film types, the pH and enzymatic stability was improved with increasing PVCL length and β-sheet content, indicating enhanced hydrophobic and hydrogen-bonded interactions between PVCL and silk. Finally, we fabricated spherical and cubical (silk/PVCL) LbL capsules of regulated permeability and enzymatic degradation. Our approach gives a unique opportunity to tune thickness, morphology, structure, and biodegradability rate of silk films and capsules by varying silk secondary structure and PVCL length. Accounting for all-aqueous fabrication and the biocompatibility of both polymers these biodegradable materials provide novel platforms for delivery systems and medical devices.
我们报道了通过丝素蛋白与聚（N-乙烯基己内酰胺）（PVCL）通过氢键和疏水相互作用进行逐层（LbL）组装获得的可酶促降解的纳米薄膜涂层。我们发现，通过浸渍和旋转辅助LbL控制的丝β-折叠含量以及PVCL分子量均以纳米级精度调节薄膜厚度、微观结构、pH稳定性和生物降解性。（丝素蛋白/PVCL）薄膜的厚度随着PVCL分子量的增加和沉积pH值的降低而增加。组装pH对浸渍薄膜的薄膜生长影响更为显著。这些体系在pH < 5时，随着PVCL分子量的增加，厚度显著增加，但在pH≥5时，厚度与聚合物链长度无关。我们还发现，与浸渍薄膜相比，旋转辅助薄膜在较高pH值下表现出更高的稳定性，并且对酶降解具有抗性。对于这两种薄膜类型，随着PVCL长度和β-折叠含量的增加，pH和酶稳定性均得到改善，这表明PVCL与丝素蛋白之间的疏水和氢键相互作用增强。最后，我们制备了具有可控渗透性和酶促降解性的球形和立方体（丝素蛋白/PVCL）LbL胶囊。我们的方法提供了一个独特的机会，通过改变丝素蛋白的二级结构和PVCL长度来调节丝素蛋白薄膜和胶囊的厚度、形态、结构和生物降解速率。考虑到全水性制备以及两种聚合物的生物相容性，这些可生物降解材料为递送系统和医疗设备提供了新的平台。
