Synthesis and characterization of bioactive molecules grafted on poly(ε-caprolactone) by click chemistry

A facile and efficient strategy to graft bioactive molecules (nicotinic acid, p-aminobenzoic acid, and phthaloyltryptophan) onto poly(epsilon-caprolactone) (P(epsilon CL)) was achieved by copper-catalyzed Huisgen's 1,3-dipolar cycloaddition known as click reaction. P(alpha Cl epsilon CL), with 10, 20, and 30% of alpha-chloro-epsilon-caprolactone (alpha Cl epsilon CL) units were copolymerized by ring opening polymerization using epsilon CL and alpha Cl epsilon CL as starting materials in the presence of 1,4-butanediol and Sn(Oct)(2). Subsequently, the chloride pendent was converted to azide followed by cycloaddition with terminal alkyne derivatives of the aforementioned bioactive molecules. The complete addition was accomplished at all ratios. The characteristic molecular features of these copolymers were evaluated by FTIR, NMR, and GPC. Thermal analysis data indicated that the grafted compounds led to polymorphic alteration and different pattern of thermal degradation depending on the molecular structure and the size of the grafted compounds. They are the basis for further development of grafted copolymer as drug delivery carriers. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.