Synthesis and characterization of poly(aspartic acid) derivatives conjugated with various amino acids

Novel derivatives of poly(aspartic acid) conjugated with various amino acids and their amphiphilic copolymers were synthesized and characterized. Methyl esters of various amino acids (in their hydrochloride form) were synthesized from the reaction of amino acids with methanol in the presence of chlorotrimethylsilane (TMSCl). Aminolysis reaction onto polysuccinimide (PSI) using various amino acid methyl esters in the presence of catalyst and the followed hydrolysis provided the corresponding amino acid-conjugated poly(aspartic acid) derivatives in high reaction yield. Amino acid—conjugated amphiphilic analogs were also prepared by introducing hydrophobic alkylamine along with amino acid using a similar procedure. The chemical structures of copolymers were confirmed by FT-IR and ¹H NMR spectroscopy. The physicochemical properties of amphiphilic copolymers were characterized using dynamic light scattering (DLS), fluorescence spectroscopy and field emission scanning electron microscopy (FE-SEM). In addition, the in vitro cell viability of the copolymers was examined. These polymers have potential applications in the pharmaceutical and cosmetic fields as delivery vehicles for bioactive molecules.