Cohen S, Yoshioka T, Lucarelli M, Hwang L H, Langer R
Department of Chemical Engineering, MIT, Cambridge, Massachusetts 02139.
Pharm Res. 1991 Jun;8(6):713-20. doi: 10.1023/a:1015841715384.
This paper describes an investigation of the use of poly(lactic/glycolic acid) polymers for long-term delivery of high molecular weight, water-soluble proteins. Poly(lactic/glycolic acid) (PLGA) microspheres, containing (fluorescein isothiocyanate)-labeled bovine serum albumin and (fluorescein isothiocyanate)-labeled horseradish peroxidase, were prepared by a modified solvent evaporation method using a double emulsion. The microspheres were spherical with diameters of 55-95 microns and encapsulated more than 90% of the protein. The preparation method was gentle and maintained enzyme activity and protein solubility. Stability studies showed that the encapsulation of an enzyme inside PLGA microspheres can protect them from activity loss. When not placed inside PLGA microspheres, (fluorescein isothiocyanate)-labeled horseradish peroxidase lost 80% of its activity in solution at 37 degrees C in a few days, whereas inside the PLGA microspheres it retained more than 55% of its activity after 21 days of incubation at 37 degrees C. In vitro release studies revealed that different release profiles (i.e., near-constant or biphasic) and release rates can be achieved by simply modifying factors in the preparation procedure such as mixing rate and volume of inner water and organic phases. Degradation studies by scanning electron microscopy and gel-permeation chromatography suggested that the mechanism responsible for protein release is mainly through matrix erosion.
本文描述了一项关于使用聚（乳酸/乙醇酸）聚合物长期递送高分子量水溶性蛋白质的研究。采用改良的溶剂蒸发法并通过双乳液制备了含有（异硫氰酸荧光素）标记的牛血清白蛋白和（异硫氰酸荧光素）标记的辣根过氧化物酶的聚（乳酸/乙醇酸）（PLGA）微球。这些微球呈球形，直径为55 - 95微米，包封了超过90%的蛋白质。该制备方法温和，能保持酶活性和蛋白质溶解性。稳定性研究表明，将酶包封在PLGA微球内可保护其不丧失活性。当（异硫氰酸荧光素）标记的辣根过氧化物酶不置于PLGA微球内时，在37℃的溶液中几天内就会丧失80%的活性，而在PLGA微球内，在37℃孵育21天后仍保留超过55%的活性。体外释放研究表明，通过简单改变制备过程中的因素，如混合速率以及内水相和有机相的体积，可实现不同的释放曲线（即近恒定或双相）和释放速率。通过扫描电子显微镜和凝胶渗透色谱进行的降解研究表明，蛋白质释放的机制主要是通过基质侵蚀。
