Two methacrylate containing amino acid based chiral monomers, Boc-L-alanine methacryloyloxyethyl ester (Boc-Ala-HEMA) and Boc-L-phenylalanine methacryloyloxyethyl ester (Boc-Phe-HEMA), were polymerized by the reversible addition-fragmentation chain transfer (RAFT) process to afford welldefined amino acid based polymers with controlled molecular weight, narrow molecular weight distribution, and precise chain end structure. Linear pseudo-first-order kinetics and number average molecular weight dependence on conversion were observed for the RAFT polymerizations. Di-block copolymers were prepared by RAFT polymerization of methyl methacrylate using poly(Boc-L-alanine methacryloyloxyethyl ester) or poly(Boc-L-phenylalanine methacryloyloxyethyl ester) as macro-chain transfer agents. Subsequent deprotection of the Boc group produced architectures with a primary amine moiety at the side chain, which showed pH responsiveness. The specific rotations of both the chiral monomers and corresponding homo-and block copolymers were studied and alteration of specific rotation due to transformation of monomer to polymer was noticed. In addition, the surface charge of various polymeric architectures was studied using dynamic light scattering (DLS) measurements. The self-assembly of block copolymer films was investigated by atomic force microscopy (AFM). These pH-responsive cationic polymers can potentially be extended for the delivery of small interfering RNA.

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Developing safe and effective nanocarriers for multitype of delivery system is advantageous for several kinds of successful biomedicinal therapy with the same carrier. In the present study, we have designed amino acid biomolecules derived hybrid block copolymers which can act as a promising vehicle for both drug delivery and gene transfer. Two representative natural chiral amino acid-containing (l-phenylalanine and l-alanine) vinyl monomers were polymerized via reversible addition-fragmentation chain transfer (RAFT) process in the presence of monomethoxy poly(ethylene glycol) based macro-chain transfer agents (mPEGn-CTA) for the synthesis of well-defined side-chain amino-acid-based amphiphilic block copolymers, monomethoxy poly(ethylene glycol)-b-poly(Boc-amino acid methacryloyloxyethyl ester) (mPEGn-b-P(Boc-AA-EMA)). The self-assembled micellar aggregation of these amphiphilic block copolymers were studied by fluorescence spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Potential applications of these hybrid polymers as drug carrier have been demonstrated in vitro by encapsulation of nile red dye or doxorubicin drug into the core of the micellar nanoaggregates. Deprotection of side-chain Boc- groups in the amphiphilic block copolymers subsequently transformed them into double hydrophilic pH-responsive cationic block copolymers having primary amino groups in the side-chain terminal. The DNA binding ability of these cationic block copolymers were further investigated by using agarose gel retardation assay and AFM. The in vitro cytotoxicity assay demonstrated their biocompatible nature and these polymers can serve as "smart" materials for promising bioapplications.

We report the synthesis and characterization of well-defined polymers from oleic acid as the bio-renewable resource. Double bonds in oleate side-chains in the polymer are further modified by thiol-ene reaction, epoxidation, and cross-linking.

A strategy was developed for the controlled synthesis of side-chain peptide containing pH-responsive polymers with an antiparallel β-sheet motif, which was independent of solvent polarity, PEGylation of homopolymers, the block length of PEG or peptidic segments in the block copolymer and temperature.