Bioconjugation of Biodegradable Poly (lactic/glycolic acid) to Protein, Peptide, and Anti-Cancer Drug: An Alternative Pathway for Achieving Controlled Release from Micro- and Nanoparticles

Biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) was chemically conjugated to two model protein drugs, lysozyme and a tryptophan derivative. Biodegradable PLGA is an aliphatic polyester that has no available functional groups in its backbone for the drug conjugation. The conjugation approach can be extended to the fabrication of nanoparticles encapsulated with hydrophilic drugs. Doxorubicin conjugated to water soluble polymers or incorporated into the core region of polymeric micelles in order to achieve passive targeting has been used as a potent anticancer drug for the treatment of various solid tumors. Injectable formulation of PLGA microspheres containing leutenizing hormone analogs has been one of the more successfully commercialized drug delivery products. One of the two terminal functional groups, hydroxyl and carboxylic acid, on the PLGA chains was activated by suitable coupling agents and then reacted to appropriate functional groups on the protein molecules.