Poly(L-aspartic acid) derivative soluble in a volatile organic solvent for biomedical application

In order to develop a novel functional poly(L-amino acid) that can dissolve in volatile organic solvents, we prepared poly[L-aspartic acid-g-(3-diethylaminopropyl)]-b-poly(ethylene glycol) [poly(L-Asp-g-DEAP)-b-PEG] via the conjugation of 3-diethylaminopropyl (DEAP) to carboxylate groups of poly(L-Asp) (M(n) 4 K)-b-PEG (M(n) 2 K). This poly(L-aspartic acid) derivative evidenced a relatively high solubility in volatile organic solvents such as dichloromethane, chloroform, and acetone. We fabricated a model nanostructure (i.e., polymeric micelle) using poly(L-Asp-g-DEAP)-b-PEG by the film rehydration method, which involves the simple removal of the volatile organic solvent (dichloromethane) used to dissolve polymer, reducing concerns about organic solvents remaining in a nano-sized particle. Interestingly, this micelle showed the pH-stimulated release of encapsulated model drug [i.e., doxorubicin (DOX)] due to the protonation of DEAP according to the pH of the solution. We expect that this poly(L-aspartic acid) derivative promises to provide pharmaceutical potential for constituting a new stimuli-sensitive drug carrier for various drug molecules.