Dinabandhu Pramanick

Synthesis and biodegradation of copolyesters from citric acid and glycerol

SummarySeven samples of cross-linked co-polyesters of citric acid and glycerol from seven different mole ratios of the reactants have been synthesised as initially insoluble amorphous solids which become soluble in water within 8–10 days due to partial hydrolysis of the cross-links. They have been characterised by their IR spectra, glass transition temperature and swelling behaviour. The acid to glycerol mole ratios 0.83 and 0.88 produce maximum cross-link density. Microbial degradation of the polymer samples in aqueous suspension has been studied using the fungus Aspergillus niger and the bacterium E. coli. All the polymer samples are degraded by Aspergillus niger and E. coli and the more cross-linked products have been found to be more degradable. The possible use of these cross-linked co-polyesters as matrices for controlled release of drugs has been illustrated.

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.

Synthesis and biodegradation of copolyesters derived from glutamic acid

SummaryCopolyesters of glutamic acid hydrochloride and 1,2-ethane diol, 1, 3-butane diol, 1,4-butane diol, 1,6-hexane diol and glycerol have been synthesised and characterised by number average molecular weights, I.R.spectra and elemental analysis. Microbial degradation of the co-polyesters has been studied using the fungus Aspergillus niger and the bacterium E.coli. All the polymer samples are degraded by these microorganisms. The less polar copolyesters are more readily degraded by the fungus while the bacterium more efficiently degrades the polymers having a higher proportion of α-NH2 group. The facile attachment of a suitable drug through the free amine groups of the copolyesters has been illustrated to indicate their possible use as carrier polymers for drugs.