Amino Acid Oligomer Microspheres as Drug Delivery Systems. I. Synthesis of Oligo(Amino Acids) via NCAs and Their Microsphere Formation

Abstract

Some thermally derived proteinoids are known to form hollow microspheres under specific conditions. In this study, oligomers consisting of L-aspartic acid, L-glutamic acid, L-phenylalanine, and L-tyrosine were prepared through the corresponding a-amino acid-N carboxyanhydrides (NCAs). The oligo(amino acids) synthesized by NCA method had better control on the composition as well as molecular weight. These oligo(amino acids) were found to spontaneously form microspheres under acidic conditions. It was also found that is possible to encapsulate a variety of drug entities within these unique self-assembling systems. The microspheres which form spontaneously at low pH's also dissolve in water at neutral pH and consequently have the potential to be used as oral drug delivery systems.