Effect of basic amino acid on acid accumulation during poly(D,L-lactide-co-glycol ide)degradation in vitro○

Wei ZHOU; Bin LIU; Xiaozhen DAI; Chan ZHOU; Shaozhe CAI; Guoli SONG

ABSTRACT

BACKGROUND:

Poly(D,L-lactide-co-glycolide)(PLGA)may produce lactic acid and glycolic acid when PLGA degrades,thus leading to the acid accumulation and inducing the inflammatory reaction locally.

OBJECTIVE:

To investigate the effect of lysine,histidine and arginine on regulating the acid accumulation of PLGA copolymer during the degradation.

DESIGN:

Repeated measurement and experiment.TIME AND

SETTING:

The experiments were performed in the College of Bioengineering.Chongqing University from July 2006 to August 2007.MATERIALSPILGA(8020)was produced by Sigma(USA);Lysine,histidine and arginine(purlty>99%)were purchased from Sigma(USA);Chitosan(deacetylation degree85%)was purchased from Chengdu Kelong Chemical Reagent Factory;Algin(viscosity1.05-1.15)was purchased from Tianiin Damao Chemical Reagent Factory.

METHODS:

Lysine,histidine and arginine were added into PLGA with the proportion of 5%(w/v)and 10%(w/v)respectively.The resultant film sample was put into a bottle with tri-distilled-water for 2-month degradation at 37℃.The pH value of degradation solution was detected by pH meter;Each film sample was taken out and lyophilized 12 hours to get its dry weight and calculate mass loss ratio.Each variety of the solution was sampled three specimens,the average pH value,average initial weight and average finial weight of these three specimens were taken as the indices at each sampling time point,respectively.Accordingly,the regulation effect of basic amino acid was comparexl with that of algin,chitosan and NaHCO3.MAIN OUTCOME

MEASURES:

The changes of pH value of degradation solution;the mass loss ratio of the composite.

RESULTS:

Each basic additive could relieve the acid accumulation,among them,NaHCO3 was the strongest,while algin and chitosan showed a lowest capacity,basic amino acid was moderate;The suitable regulation effect could be achieved at a level of 5%lysine.

CONCLUSION:

Basic amino acid can effectively regulate the acid accumulation after PLGA degrades,and the optimal concentration of lysine is 5%.