Novel crosslinking methods to design hydrogels

Future perspectives and recent advances in stimuli-responsive materials

https://www.creativepegworks.com/peptide_and_protein_pegylation_a_review_of_problems_and_solutions.pdf

Peptide and protein PEGylation: a review of problems and solutions.

The last decade of research in the physical sciences has seen a dramatic increase in the study of nanoscale materials. Today, "nanoscience" has emerged as a multidisciplinary effort, wherein obtaining a fundamental understanding of the optical, electrical, magnetic, and mechanical properties of nanostructures promises to deliver the next generation of functional materials for a wide range of applications. While this range of efforts is extremely broad, much of the work has focused on "hard" materials, such as Buckyballs, carbon nanotubes, metals, semiconductors, and organic or inorganic dielectrics. Meanwhile, the soft materials of current interest typically include conducting or emissive polymers for "plastic electronics" applications. Despite the continued interest in these established areas of nanoscience, new classes of soft nanomaterials are being developed from more traditional polymeric constructs. Specifically, nanostructured hydrogels are emerging as a promising group of materials for multiple biotechnology applications as the need for advanced materials in the post-genomic era grows. This review will present some of the recent advances in the marriage between water-swellable networks and nanoscience.

Soft nanotechnology with soft nanoparticles.

Synthesis and physicochemical characterization of end-linked poly(ethylene glycol)-co-peptide hydrogels formed by Michael-type addition.

We demonstrate formation of a hydrogel network by cross-linking functionalized poly(ethylene glycol) (PEG) and a lysine-containing polypeptide through the action of a natural tissue enzyme, transglutaminase. The enzyme reaction rate using a PEG-modified peptide substrate is the same as the reaction rate for free substrate. Both the ratio and total concentration of the two macromers determine whether gelation will occur and the nature of the gel which forms. Under suitable conditions, clear gels form and swell to give a final composition which is 90% water. Diffusion coefficients of small proteins and albumin in the gel are comparable to those in free solution. Gelation proceeds under mild conditions and thus these gels hold potential for forming highly hydrated networks around living cells.

Synthesis and Characterization of Enzymatically-Cross-Linked Poly(ethylene glycol) Hydrogels

We demonstrate control of gelation kinetics in formation of poly(ethylene glycol) (PEG) hydrogels by enzymatic cross-linking. A predictive model for gelation kinetics based on macromer structure and composition, stoichiometric ratios of reactants, cross-linking enzyme concentration, and the underlying kinetics of enzyme reaction was developed on the basis of classical Flory−Stockmayer theory. Experiments with substrate-functionalized multiarm comb PEG showed good agreement with theory upon variation of the enzyme concentration, with a slight overprediction in the time to gelation. Experiments with a substrate-functionalized difunctional PEG in conjunction with a polypeptide where macromer concentrations were varied were also consistent with theory, but with a slight underprediction of gelation time.

Jeffrey J. Sperinde

Papers

Synthesis and Characterization of Enzymatically-Cross-Linked Poly(ethylene glycol) Hydrogels

Control and Prediction of Gelation Kinetics in Enzymatically Cross-Linked Poly(ethylene glycol) Hydrogels

Tresyl-mediated synthesis: kinetics of competing coupling and hydrolysis reactions as a function of pH, temperature, and steric factors.