Investigation on a novel core-coated microspheres proteins delivery system

yAmong the different approaches to achieve protein delivery, the use of pol ymers, specifically biodegraded, holds great promise. In this work, a new m icrosphere delivery system composed of alginate microcores surrounded by a biodegradable poly-DL-lactide-poly(ethylene glycol (PELA) was designed to i mprove the loading efficiency and stability of proteins. Alginate was solid ified by calcium (MS-1), polylysine (MS-2) and chitosan (MS-3), respectivel y, to form different microcores. Human Serum Albumin (HSA), used as a model protein, was efficiently entrapped within the alginate microcores using a high-speed stirrer and then microencapsulated into PELA copolymer using a w /o/w solvent extraction method. DSC analysis of the microspheres revealed t he efficient encapsulation of the alginate microcores, while the microcores were dispersed in the PELA matrix. SDS-PAGE results showed that HSA kept i ts structural integrity during encapsulation and release procedure. Microsp heres were characterized in terms of morphology, size, loading efficiency, in vitro degradation and protein release. The degradation profiles were cha racterized by measuring the loss of microsphere mass, the decrease of polym er intrinsic viscosity and the reduction of PEG content of PELA coat. The r elease profiles were investigated from the measurement of protein presented in the release medium at various intervals. The results were that the degr adation rate of these core-coated microspheres was MS-2 > MS-1 > MS-3. The extent of burst release from the core-coated microspheres in the initial pr otein release was lower than the 27% burst release from the conventional mi crospheres. In conclusion, the work presents a new approach for macromolecu lar drugs (such as protein, peptide drugs) delivery. The core-coated micros pheres system may have potential use as a carrier for drugs that are poorly absorbed after oral administration. (C) 2001 Elsevier Science BM All right s reserved.