A NEW METHOD FOR THE SYNTHESIS OF SMOOTH, ROUND, HYDROPHILIC PROTEIN MICROSPHERES USING LOW CONCENTRATIONS OF POLYMERIC DISPERSING AGENTS

A new method for the synthesis of protein microspheres of wide size ra nge having good spherical geometry and hydrophilicity using very low c oncentrations of polymeric dispersing agents is reported. The method i nvolves the use of around 1% solution of a biomedical grade aliphatic polyurethane in a mixture of a hexane and dichloromethane as the dispe rsion medium, as opposed to a 25-30% solution of polymeric dispersing agents employed by previous workers to effect steric stabilization of the protein solution droplets. The versatility of the method is demons trated by the synthesis of albumin microspheres, as well as those of t he amphiphilic protein casein, the latter being more difficult to prep are by surfactant stabilization techniques. Significant advantages of the method include the avoidance of surfactants which become adsorbed on the particles and influence tissue reactions and drug release, and the ease of removal of the polymeric stabilizer from the final product . The method may find application for the preparation of a wide range of protein and polysaccharide microspheres for medical use.