Synthesis and biodegradation of polymers derived from aspartic acid

The synthesis of copolymers derived from aspartic acid hydrochloride, their characterization and their hydrolytic degradation and biodegradation by Aspergillus niger and E. coli have been described. The alpha-amino dicarboxylic acid has been copolymerized with 1,2-ethane diol, 1,3-butane diol, 1,4-butane diol, 1,6-hexane diol and glycerol to get copolyesters I, II, III, IV and V respectively. The polymer samples have been characterized by their number average molecular weight (Mn), elemental analysis and their i.r. spectra. The copolyester V is crosslinked. All of the copolyesters I-V undergo slow hydrolytic degradation in aqueous solution at ambient temperatures as studied by the measurement of the decrease in reduced viscosity and increase in specific conductance of their aqueous solutions. They are also degraded in aqueous suspension by the fungus Aspergillus niger and by the bacterium E. coli. Degradation by Aspergillus niger mainly depends on the polarity of the polymers, the more polar polymers being less degradable. On the other hand, degradation by E. coli is primarily dependent upon the alpha-NH2 group contents of the polymers, the alpha-NH2 group rich polymers being more degradable. The possible use of these polymers as biodegradable drug carriers has been suggested.