Poly(L-lactide)-block-poly(ethylene glycol)-Folate (PLLA-PEG-Folate, PLLA-PEG-Folic acid, or PLLA-PEG-FOL) is a functional amphiphilic block copolymer (ABC) which has Folic acid group at the end of PEG block and is used to prepare nanoparticles and micelles for targeted drug delivery. PLA-PEG is one of the most commonly used biodegradable ABC polymers for drug delivery. Folate receptors are cellular surface markers for numerous solid tumors and myeloid leukemias.
Folate targeted drug delivery has emerged as an alternative therapy for the treatment and imaging of many cancers and inflammatory diseases. Due to its small molecular size and high binding affinity for cell surface folate receptors (FR), folate conjugates have the ability to deliver a variety of molecular complexes to pathologic cells without causing harm to normal tissues. Complexes that have been successfully delivered to FR expressing cells, to date, include protein toxins, immune stimulants, chemotherapeutic agents, liposomes, nanoparticles, and imaging agents. This review will summarize the applications of folic acid as a targeting ligand and highlight the various methods being developed for delivery of therapeutic and imaging agents to FR-expressing cells.