RAFT derived fatty acid based stimuli responsive fluorescent block copolymers as DNA sensor and cargo delivery agent

Abstract

Novel capric acid-tryptophan based block copolymers with unique self-assembled feature and fluorescence property have been synthesized via reversible addition fragmentation chain transfer polymerization (RAFT) polymerization. For employing the copolymerization, at first the fatty acid based methacrylate monomer has been efficiently polymerized in presence of 4-cyano-4-(thiobenzylthio)pentanoic acid (CTP) as chain transfer agent (CTA) via RAFT polymerization. The polymerization has been preceded in a controlled fashion as confirmed by their narrow polydispersity and molecular weight determination from several methods. The capric acid based polymer then exploited as macro-CTA to synthesize the copolymers of poly(2-(methacryloyloxy)ethyl caprylate)-block-poly(tert-butyloxycarbonyl tryptophan methacryloyloxyethyl ester) (PCRMA-b-P(Boc-Trp-HEMA)) with variable block length of amino acid segment. Removal of Boc group from the amino acid block results in formation of pH responsive cationic polymers soluble in water depending on their block length. The amphiphilic polymer self-assemble in water forming higher ordered structure is then utilized as a scaffold to encapsulate and delivery of anticancer drug doxorubicin. Finally we provide a fatty acid based polymeric DNA sensor that can bind with DNA followed by significant fluorescence quenching.