0000000000246814
AUTHOR
Kerstin T. Wiss
A Versatile Grafting-to Approach for the Bioconjugation of Polymers to Collagen-like Peptides Using an Activated Ester Chain Transfer Agent
DepartmentofMaterials Science and Engineering, University of Delaware, 201DuPont Hall, Newark, Delaware 19716,Received February 24, 2009Revised Manuscript Received April 24, 2009Biohybrid materials consisting of synthetic polymers andbiological moieties have gained more and more interest in therecent years.
Morphological transformations in a dually thermoresponsive coil-rod-coil bioconjugate.
We report the conformational and assembly behavior of a thermoresponsive triblock biohybrid conjugate under aqueous conditions. The triblock comprises of poly(diethylene glycol methyl ether methacrylate) (PDEGMEMA) conjugated to the ends of a triple-helix forming collagen-like peptide. The circular dichroism (CD) experiment confirms the ability of the collagen-like peptide middle block to assemble as a triple helix in the hybrid conjugate. Above the LCST (∼35 °C), the collapse of the thermoresponsive PDEGMEMA polymer at the ends of the peptide domain resulted in a concomitant increase in the conformational stability of the peptide domain towards thermal denaturation. Upon cooling back, the …
Post-Polymerization Modification
The synthesis of functional polymers has been enriched dramatically by post-polymerization modifications. Even though it represents a synthetically very appealing approach, different synthetic concepts of organic reactions are utilized in polymer science for the synthesis of architecturally well-defined multifunctional polymers. The different classes of reactions that provide the synthetic polymer chemist with tools of unprecedented precision, thereby opening the doors for materials synthesis in an interdisciplinary world, will be summarized.
Versatile Responsive Surfaces via Hybrid Polymers Containing Acetal Side Groups
Two hybrid polymers, poly(methylsilsesquioxane)-poly(2,2-diethoxyethyl acrylate) and poly-(methylsilsesquioxane)-poly(1,3-dioxolan-2-ylmethyl acrylate), were synthesized and used for preparation of stable surface coatings. Their acetal side groups could be functionalized via solution-dipping with different primary amines and hydroxylamines after acidic deprotection and thus allowed for flexible modification of the surface hydrophilicity. Functionalization with a thermo-responsive polymer resulted in a thermo-responsive surface with temperature-dependent contact angles. Further, the two types of acetals showed different stability toward acidic treatment and could be addressed independently.
Synthesis of Reactive Telechelic Polymers Based on Pentafluorophenyl Esters
A diazo initiator and a chain transfer agent (CTA), both containing a pentafluorophenyl (PFP) activated ester, were synthesized. In a RAFT polymerization using the functionalized chain transfer agent (PFPCTA), methyl methacrylate (MMA), diethylene glycol monomethyl ether methacrylate (DEGMA), poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), and lauryl methacrylate (LMA) could successfully be polymerized into homopolymers and diblock copolymers with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from the PFP-CTA possessed an activated ester at the R-end of the polymer chain, which could be reacted with amines…
Topology-Dependent Swichability of Peptide Secondary Structures in Bioconjugates with Complex Architectures
Peptide sequences, which exhibit a reversible pH-responsive coil to α-helix secondary structure transition, are conjugated to polymer precursors to yield linear AB and graft ABA peptide-poly(ethylene oxide) conjugates. While the PEO B-block is comparable, the conjugates differ in topologies of the peptide bearing A-blocks. The influences of topology on the structure transitions in the peptide segments are investigated, comparing linear AB-bioconjugates with graft ABA-bioconjugates having multiple peptide segments combined in star or pom-pom topologies.
Facilitating polymer conjugation via combination of RAFT polymerization and activated ester chemistry
The synthesis of block copolymers via polymer conjugation of well-defined building blocks offers excellent control over the structures obtained, but often several coupling strategies need to be explored to find an efficient one depending on the building blocks. To facilitate the synthesis of polymers with adjustable functional end-groups for polymer conjugation, we report on the combination of activated ester chemistry with RAFT polymerization using a chain transfer agent (CTA) with a pentafluorophenyl ester (PFP-CTA), which allows for flexible functionalization of either the CTA prior to polymerization or the obtained polymer after polymerization. Different polymethacrylates, namely PMMA, …