Shakesheff KM, Evora C, Soriano I, Langer R
Department of Chemical Engineering, Massachusetts Institute of Technology, E25-342, 45 Carleton Street, Cambridge, Massachusetts, 02139
J Colloid Interface Sci. 1997 Jan 15;185(2):538-47. doi: 10.1006/jcis.1996.4637.
The design of biodegradable microparticle drug delivery systems with precisely tailored surface properties requires surface analytical methods that can relate polymer chemistry and fabrication parameters to the final surface chemistry of the microparticles. We demonstrate using X-ray photoelectron spectroscopy (XPS) that it is possible to identify significant variations in the surface chemistry of microparticles composed of poly(lactic acid) (PLA), poly(lactide-co-glycolide) (PLGA), or block copolymers of PLA or PLGA with poly(ethylene glycol) (PEG). These variations are related to the mechanism by which the microparticle/water interface is stabilized. This, in turn, is controlled by the interfacial surface tensions of the polymers within aqueous environments. For PEG containing block copolymers, adsorption of a surfactant, poly(vinyl alcohol) (PVA), from the aqueous medium onto the polymer is reduced compared with the PLA and PLGA polymers. This reduction is achieved because the PEG segments, within the copolymer structure, stabilize the polymer/water interface. Estimates of the relative amounts of lactide, lactide-co-glycolide, vinyl alcohol, and ethylene glycol monomer units at the microparticle surfaces are presented based on curve-fitting analysis of the XPS data.
设计具有精确定制表面性质的可生物降解微粒药物递送系统需要表面分析方法，这些方法能够将聚合物化学和制备参数与微粒的最终表面化学联系起来。我们通过X射线光电子能谱（XPS）证明，有可能识别由聚乳酸（PLA）、聚丙交酯-乙交酯共聚物（PLGA）或PLA或PLGA与聚乙二醇（PEG）的嵌段共聚物组成的微粒表面化学的显著变化。这些变化与微粒/水界面稳定化的机制有关。反过来，这又由聚合物在水性环境中的界面表面张力控制。对于含PEG的嵌段共聚物，与PLA和PLGA聚合物相比，表面活性剂聚乙烯醇（PVA）从水性介质到聚合物上的吸附减少。这种减少是因为共聚物结构中的PEG链段稳定了聚合物/水界面。基于XPS数据的曲线拟合分析，给出了微粒表面丙交酯、丙交酯-乙交酯共聚物、乙烯醇和乙二醇单体单元相对含量的估计值。
