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Relevant academic research and scientific papers

Drug conjugation to cyclic peptide-polymer self-assembling nanotubes

We show for the first time how polymeric nanotubes (NTs) based on self-assembled conjugates of polymers and cyclic peptides can be used as an efficient drug carrier. RAPTA-C, a ruthenium-based anticancer drug, was conjugated to a statistical co-polymer based on poly(2-hydroxyethyl acrylate) (pHEA) and poly(2-chloroethyl methacrylate) (pCEMA), which formed the shell of the NTs. Self-assembly into nanotubes (length 200-500nm) led to structures exhibiting high activity against cancer cells.

Study of (Cyclic Peptide)–Polymer Conjugate Assemblies by Small-Angle Neutron Scattering

We present a fundamental study into the self-assembly of (cyclic peptide)–polymer conjugates as a versatile supramolecular motif to engineer nanotubes with defined structure and dimensions, as characterised in solution using small-angle neutron scattering (SANS). This work demonstrates the ability of the grafted polymer to stabilise and/or promote the formation of unaggregated nanotubes by the direct comparison to the unconjugated cyclic peptide precursor. This ideal case permitted a further study into the growth mechanism of self-assembling cyclic peptides, allowing an estimation of the cooperativity. Furthermore, we show the dependency of the nanostructure on the polymer and peptide chemical functionality in solvent mixtures that vary in the ability to compete with the intermolecular associations between cyclic peptides and ability to solvate the polymer shell.

Hyperbranched alternating block copolymers using thiol-yne chemistry: Materials with tuneable properties

Alternating-block hyperbranched polymers were synthesized using the highly versatile thiol-yne reaction. Dimethyl acrylamide-styrene and tert-butyl acrylate-styrene polymers were prepared, with subsequent hydrolysis of the tert-butyl ester to acrylic acid

Hyperbranched polymers by thiol-yne chemistry: From small molecules to functional polymers

(Chemical Equation Presented) A new synthesis of hyperbranched polymers is outlined. This paper presents the synthesis of hyperbranched polymers by the recently highlighted thiol-yne reaction. In the thiol-yne reaction, a catalytic amount of photoinitiato

Effects of graft length and density of well-defined graft polymers on the thermoresponsive behavior and self-assembly morphology

A series of well-defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)-graft-poly(N- isopropylacrylate) (PGMA-g-PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self-assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co-relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA45-g-PNIPAM20 and PGMA45-g-PNIPAM46 with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA45-g-PNIPAM (73, 50%) shows a spherical-like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self-assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self-assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density.

Altering peptide fibrillization by polymer conjugation

A strategy is presented that exploits the ability of synthetic polymers of different nature to disturb the strong self-assembly capabilities of amyloid based β-sheet forming peptides. Following a convergent approach, the peptides of interest were synthesized via solid-phase peptide synthesis (SPPS) and the polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by a copper(I) catalyzed azide-alkyne cycloaddition (CuAAC) to generate the desired peptide-polymer conjugates. This study focuses on a modified version of the core sequence of the β-amyloid peptide (Aβ), Aβ(16-20) (KLVFF). The influence of attaching short poly(N-isopropylacrylamide) and poly(hydroxyethylacrylate) to the peptide sequences on the self-assembly properties of the hybrid materials were studied via infrared spectroscopy, TEM, circular dichroism and SAXS. The findings indicate that attaching these polymers disturbs the strong self-assembly properties of the biomolecules to a certain degree and permits to influence the aggregation of the peptides based on their β-sheets forming abilities. This study presents an innovative route toward targeted and controlled assembly of amyloid-like fibers to drive the formation of polymeric nanomaterials.

"Click" synthesis of thermally stable au nanoparticles with highly grafted polymer shell and control of their behavior in polymer matrix

Thermally stable core-shell gold nanoparticles (Au NPs) with highly grafted polymer shells were synthesized by combining reversible addition-fragmentation transfer (RAFT) polymerization and click chemistry of copper-catalyzed azide-alkyne cycloaddition (CuAAC). First, alkyne-terminated poly(4-benzylchloride-b-styrene) (alkyne-PSCl-b-PS) was prepared from the alkyne-terminated RAFT agent. Then, an alkyne-PSCl-b-PS chain was coupled to azide-functionalized Au NPs via the CuAAC reaction. Careful characterization using FT-IR, UV-Vis, and TGA showed that PSCl-b-PS chains were successfully grafted onto the Au NP surface with high grafting density. Finally, azide groups were introduced to PSCl-b-PS chains on the Au NP surface to produce thermally stable Au NPs with crosslinkable polymer shell (Au-PSN3-b-PS 1). As the control sample, PS-b-PSN3-coated Au NPs (Au-PSN3-b-PS 2) were made by the conventional "grafting to" approach. The grafting density of polymer chains on Au-PSN3-b-PS 1 was found to be much higher than that on Au-PSN3-b-PS 2. To demonstrate the importance of having the highly packed polymer shell on the nanoparticles, Au-PSN 3-b-PS 1 particles were added into the PS and PS-b-poly(2- vinylpyridine) matrix, respectively. Consequently, it was found that Au-PSN 3-b-PS 1 nanoparticles were well dispersed in the PS matrix and PS-b-P2VP matrix without any aggregation even after annealing at 220 °C for 2 days. Our simple and powerful approach could be easily extended to design other core-shell inorganic nanoparticles.