PREPARATION OF HYDROPHOBIC AND HYDROPHILIC ALBUMIN MICROSPHERES AND DETERMINATION OF SURFACE CARBOXYLIC-ACID AND AMINO RESIDUES

Albumin microspheres (MS) have been studied extensively as delivery sy stems for targeting drugs since they are biodegradable, non-toxic, rel atively easy to prepare and their size range can be controlled. A meth od for albumin MS production was developed which was faster, processed larger quantities of starting material than previous methods, and had chemically reactive groupings on the MS surface to which ligands coul d be attached. Relatively hydrophobic, hydrophilic and also carboxymet hylated MS were manufactured. The number of carboxylic acid residues w as determined on the surface of these MS using C-14-glycine ethyl este r hydrochloride as a probe, and the number of amino groups was determi ned using C-14-sodium acetate as a probe. The number of carboxylic aci d residues per unit surface area for the hydrophobic, hydrophilic and carboxymethylated MS was 2.1 x 10(4), 4.1 x 10(4) and 8.4 x 10(4), res pectively, and the number of amino acid residues was 2.2 x 10(3), 5.0 x 10(2) and 5.0 x 10(2), respectively. (C) 1997 Elsevier Science B.V.