Stability of Poly(ethylene glycol) Modified Proteins

我们试图通过增加其稳定性来改善生物相容性聚（乳酸-共-乙醇酸）（PLGA）微球中蛋白质的受控递送。这将促进蛋白质药物在健康应用中的广泛使用，这仍然受到其固有结构不稳定性的限制。我们打算进行研究，以防止有害的蛋白质聚集和失活，这些蛋白质聚集和失活发生在它们被封装到PLGA微球期间所涉及的严重应力下（例如，暴露于有机溶剂-水界面）。我们假设这可以通过用聚乙二醇（PEG）共价修饰蛋白质来实现。主要假设是，将PEG共价连接到药物蛋白质表面将降低其对聚集和失活的易感性（a）在封装在PLGA微球中时，（B）在储存期间的固态下，和（c）在体外释放期间。 此外，PEG修饰还可能改善蛋白质从通过非水性（例如，油包油包固体）或半非水性（即，水包油包固体）方法。 原因是PEG蛋白可溶于许多合适的有机溶剂。这将导致PEG-蛋白质在聚合物基质中更好的分布，并提供减少的突释。我们将使用各种方法（例如，水包油包水、水包油包固体和喷墨辅助封装）。蛋白质结构和稳定性数据将使用多种光谱（例如，FT-IR、FT-Raman、圆二色性和荧光光谱）和生物化学技术。结构数据将与稳定性参数相关，例如器械的累积蛋白质释放、比生物活性和蛋白质聚集。此外，稳定性 并且结构数据将与表面改性的化学性质和程度相关。这些数据将被用来开发压力特定的策略，以系统地消除蛋白质失活和聚集在封装和释放。

We seek to improve the controlled delivery of proteins from biocompatible poly(lactic-co-glycolic) acid (PLGA) microspheres by increasing their stability. This will further the widespread use of protein pharmaceuticals in health applications which is still limited by their inherent structural lability. We intend to carry out studies that will prevent detrimental protein aggregation and inactivation which occur when they are exposed to the severe stress involved during their encapsulation into PLGA microspheres (e.g., exposure to organic solvent-water interfaces). We hypothesize that this can be achieved by covalent modification of proteins with poly(ethylene glycol) (PEG). Main hypotheses are that covalently attaching PEG to the surface of pharmaceutical proteins will reduce their susceptibility towards aggregation and inactivation (a) upon encapsulation in PLGA microspheres, (b) in the solid state during storage, and (c) during in vitro release. Furthermore, PEG-modification will likely also improve the release of proteins from PLGA microspheres prepared by non-aqueous (e.g., solid-in-oil-in-oil) or semi non-aqueous (i.e., solid-in-oil-in-water) methods. The reason is that PEG-proteins are soluble in many suitable organic solvents. This should result in a better distribution of PEG-protein in the polymer matrix and afford a reduced burst release. We will encapsulate PEG-modified proteins in PLGA microspheres using various methodologies (e.g., water-in-oil-in-water, solid-in-oil-in-water, and ink jet assisted encapsulation). Protein structural and stability data will be obtained using a manifold of spectroscopic (e.g., FT-IR, FT-Raman, circular dichroism and fluorescence spectroscopy) and biochemical techniques. The structural data will be correlated with stability parameters, such as cumulative protein release from the devices, specific biological activity, and protein aggregation. Furthermore, stability and structural data will be related to the chemical nature and degree of surface modification. These data will be used to develop stress-specific strategies to systematically eradicate protein inactivation and aggregation during encapsulation and release.