Facile Synthesis of Glycopolypeptides by Combination of Ring-Opening Polymerization of an Alkyne-Substituted N -carboxyanhydride and Click “Glycosylation”

Stimuli-sensitive synthetic polypeptide-based materials for drug and gene delivery

Stimuli-sensitive synthetic polypeptides are unique biodegradable and biocompatible synthetic polymers with structures mimicking natural proteins. These polymers exhibit reversible secondary conformation transitions and/or hydrophilic-hydrophobic transitions in response to changes in environmental conditions such as pH and temperature. The stimuli-triggered conformation and/or phase transitions lead to unique self-assembly behaviors, making these materials interesting for controlled drug and gene delivery applications. Therefore, stimuli-sensitive synthetic polypeptide-based materials have been extensively investigatid in recent years. Various polypeptide-based materials, including micelles, vesicles, nanogels, and hydrogels, have been developed and tested for drug- and gene-delivery applications. In addition, the presence of reactive side groups in some polypeptides facilitates the incorporation of various functional moieties to the polypeptides. This Review focuses on recent advances in stimuli-sensitive polypeptide-based materials that have been designed and evaluated for drug and gene delivery applications. In addition, recent developments in the preparation of stimuli-sensitive functionalized polypeptides are discussed.

Hierarchical self-assembly and secondary structures of linear polypeptides graft onto POSS in the side chain through click chemistry

A hexagonal cylinder packing nanostructure featuring α-helical conformations and POSS aggregates was proposed in this study.

Facile preparation of a cationic poly(amino acid) vesicle for potential drug and gene co-delivery

A novel pH-responsive poly(amino acid) grafted with oligocation was prepared through the combination of ring-opening polymerization (ROP) and subsequent atom transfer radical polymerization (ATRP). Firstly, poly(γ-2-chloroethyl-L-glutamate) (PCELG) with a pendent 2-chloroethyl group was synthesized through ROP of γ-2-chloroethyl-L-glutamate N-carboxyanhydride (CELG NCA) using n-hexylamine as the initiator. Then, PCELG was used to initiate the ARTP of 2-aminoethyl methacrylate hydrochloride (AMA), yielding poly(L-glutamate)-graft-oligo(2-aminoethyl methacrylate hydrochloride) (PLG-g-OAMA). The pK(a) of PLG-g-OAMA was 7.3 established by the acid-base titration method. The amphiphilic poly(amino acid) could directly self-assemble into a vesicle in PBS. The vesicle was characterized by TEM and DLS. Hydrophilic DOX·HCl was loaded into the hollow core of the vesicle. The in vitro release behavior of DOX·HCl from the vesicle in PBS could be adjusted by the solution pH. In vitro cell experiments revealed that the vesicle could reduce the toxicity of the DOX·HCl. In addition, the preliminary gel retardation assay displayed that PLG-g-OAMA could efficiently bind DNA at a PLG-g-OAMA/DNA weight ratio of 0.3 or above, indicating its potential use as a gene carrier. More in-depth studies of the PLG-g-OAMA vesicle for drug and gene co-delivery in vitro and in vivo are in progress.

Ring-Opening Polymerization of γ-(4-Vinylbenzyl)-(L)-Glutamate N-Carboxyanhydride for the Synthesis of Functional Polypeptides

Introducing various pendant functional groups and building blocks of interest to polypeptides in a highly efficient, controlled manner is crucial to access polypeptide materials with desired structures and functions. In this study, we synthesized γ-(4-vinylbenzyl)-(L)-glutamate N-carboxyanhydride (VB-Glu-NCA), which was readily obtained and purified in large quantity. VB-Glu-NCA monomer was subsequently used for the synthesis of polypeptides containing conjugation-amenable, pendant vinyl functional groups. Controlled, living polymerizations of VB-Glu-NCA were achieved by using hexamethyldisilazane (HMDS) as the initiator, catalytic amounts of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the co-catalyst, and nitrobenzene as the inhibitor of radical-induced side reactions on the vinyl group of VB-Glu-NCA. The resulting poly(γ-(4-vinylbenzyl)-(L)-glutamate) (PVBLG) gave rise to polypeptides containing pendant functional groups or moieties through various vinyl chemistries.

Ligand accessibility to receptor binding sites enhanced by movable polyrotaxanes

Functionalized polyrotaxanes are utilized to investigate the relation to multivalent interactions between the mannose moiety and Con A immobilized surfaces. According to the results of SPR spectroscopy, the mannose-conjugated polyrotaxanes show a higher response than any other mannose conjugate on both surfaces of high- and low-density Con A. Moreover, the results of the FRET analysis suggest that the mobility of α-cyclodextrins in the polyrotaxane more efficiently contributes to their binding interactions in a multivalent manner. This well-defined polyrotaxane system provides control over ligand density, ligand mobility, and gives an efficient response to the biological interaction receptor, which has not been easy to achieve in covalently bound polymeric systems.

Synthesis of polypeptides by ring-opening polymerization of α-amino acid N-carboxyanhydrides

This chapter summarizes methods for the synthesis of polypeptides by ring-opening polymerization. Traditional and recently improved methods used to polymerize α-amino acid N-carboxyanhydrides (NCAs) for the synthesis of homopolypeptides are described. Use of these methods and strategies for the preparation of block copolypeptides and side-chain-functionalized polypeptides are also presented, as well as an analysis of the synthetic scope of different approaches. Finally, issues relating to obtaining highly functional polypeptides in pure form are detailed.