Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur, Uttar Pradesh, India.
Int J Nanomedicine. 2012;7:61-71. doi: 10.2147/IJN.S26453. Epub 2011 Dec 30.
Hydrophobic biopolymers such as polylactide-co-glycolide (PLGA, 85:15) have been extensively explored as scaffolding materials for tissue engineering applications. More recently, electrospun microfiber-based and nanofiber-based scaffolds of PLGA have received increased attention because they act as physical mimics of the fibrillar extracellular matrix. However, the hydrophobicity of the PLGA microfiber surface can limit its use in biomedical applications. Therefore, in a previous study, we fabricated Pluronic(®) F-108 (PF-108)-blended PLGA microfibrous scaffolds that alleviated the hydrophobicity associated with PLGA by enriching the surface of microfibers with the ethylene oxide units present in PF-108.
In this study, we report the influence of the extent of surface enrichment of PLGA microfibers on their interaction with two model proteins, ie, bovine serum albumin (BSA) and lysozyme. BSA and lysozyme were adsorbed onto PLGA microfiber meshes (unmodified and modified) and studied for the amount, secondary structure conformation, and bioactivity of released protein.
Irrespective of the type of protein, PF-108-blended PLGA microfibers showed significantly greater protein adsorption and release than the unblended PLGA samples. However, in comparison with BSA, lysozyme showed a 7-9-fold increase in release. The Fourier transform infrared spectroscopy studies for secondary structure determination demonstrated that irrespective of type of microfiber surface (unblended or blended), adsorbed BSA and lysozyme did not show any significant change in secondary structure (α-helical content) as compared with BSA and/or lysozyme in the free powder state. Further, the bioactivity assay of lysozyme released from blended PLGA microfiber meshes demonstrated 80%-85% bioactivity, indicating that the process of adsorption did not significantly affect biological activity. Therefore, this study demonstrated that the decreased hydrophobicity of blended PLGA microfibrous meshes not only improved the amount of protein adsorbed (lysozyme and BSA) but also maintained the secondary structure and bioactivity of the adsorbed proteins.
Modulating the hydrophobicity of PLGA via blending with PF-108 could be a viable strategy to improve its interaction with proteins and subsequent cell interaction in tissue engineering applications.
聚乳酸-共-乙醇酸（PLGA，85:15）等疏水性生物聚合物已被广泛探索作为组织工程应用的支架材料。最近，基于电纺的微纤维和纳米纤维支架的 PLGA 受到了越来越多的关注，因为它们作为纤维细胞外基质的物理模拟物发挥作用。然而，PLGA 微纤维表面的疏水性可能会限制其在生物医学应用中的使用。因此，在之前的研究中，我们制备了聚氧乙烯（PF-108）共混 PLGA 微纤维支架，通过丰富微纤维表面的 PF-108 中的氧化乙烯单元，缓解了与 PLGA 相关的疏水性。
在这项研究中，我们报告了 PLGA 微纤维表面的富集程度对其与两种模型蛋白（即牛血清白蛋白（BSA）和溶菌酶）相互作用的影响。BSA 和溶菌酶被吸附到 PLGA 微纤维网（未改性和改性）上，并研究了释放蛋白的量、二级结构构象和生物活性。
无论蛋白质的类型如何，PF-108 共混 PLGA 微纤维显示出比未共混 PLGA 样品显著更大的蛋白质吸附和释放。然而，与 BSA 相比，溶菌酶的释放增加了 7-9 倍。用于确定二级结构的傅里叶变换红外光谱研究表明，无论微纤维表面的类型（未共混或共混）如何，与自由粉末状态的 BSA 和/或溶菌酶相比，吸附的 BSA 和溶菌酶的二级结构（α-螺旋含量）没有任何显著变化。此外，从共混 PLGA 微纤维网中释放的溶菌酶的生物活性测定表明，80%-85%的生物活性，表明吸附过程并未显著影响生物活性。因此，本研究表明，共混 PLGA 微纤维网疏水性的降低不仅提高了吸附蛋白（溶菌酶和 BSA）的量，而且保持了吸附蛋白的二级结构和生物活性。
通过与 PF-108 共混来调节 PLGA 的疏水性可能是一种可行的策略，可以改善其与蛋白质的相互作用，并在组织工程应用中随后的细胞相互作用。
