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Amphiphilic block copolymers comprised of poly(lactic acid-co-glycolic acid) and poly(ethylene glycol) are thermogelling materials with biodegradable blocks. The thermogel forming biodegradable delivery system has two major benefit : 1) First, thermogelation allows for delivery over the course of a period of time after introduction of what is initially a liquid; 2) The material safely biodegrades away once it is no longer necessary to lactic and glycolic acids as well as the water-soluble poly(ethylene glycol) block, which at molecular weights below 20KDa are safely eliminated from the body by the kidneys.

The thermogelation properties of poly(lactic acid-co-glycolic acid)-block-poly(ethylene glycol)-block-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) copolymers have been extensively used in research for controlled delivery.