Cascin microspheres: preparation and evaluation as a carrier for controlled drug delivery

Abstract

A method for the preparation of smooth, spherical, glutaraldehyde-crosslinked microspheres of the amphiphilic protein, caScin, is reported. CaScin microspheres (CAS/MS) were found to be even more hydrophilic than comparable microspheres made from bovine serum albumin by the method developed in this laboratory several years ago and were readily dispersed in water without aggregation. Enzymatic degradation studies with the enzyme protease suggested that the CASJMS with lower crosslink density degraded faster than those with higher crosslink density. Methotrexate (MTX) was incorporated into the CASJMS during microsphere synthesis to the extent of 15 wt% loading, and in vitro release was examined in phosphate buffer at 37°C. Drug release of 35% was observed in 24 h, suggesting that most of the incorporated drug was strongly associated with the CASJMS. Similar release was observed for MTX loaded albumin spheres prepared in the same manner. Based on these studies, caScin appears to be a highly promising, low-cost, bioacceptable protein for the synthesis of drug conjugates and microsphere carrier systems for targeted drug delivery.