Degradable Protein-loaded Polymer Capsules Fabricated by Thiol-disulfide Cross-linking Reaction at Liquid-liquid Interface

In these years, the encapsulation of proteins for protection and delivery purpose has attracted great interest. In this research,W/O emulsion droplets were used as soft templates and bovine serum albumin(BSA) encapsulated hollow capsules were prepared by liquid-liquid interfacial thiol-disulfide exchange reaction. Block copolymer chains with pendant pyridyl disulfide groups are located at liquid-liquid interface, and upon addition of a macromolecular crosslinking agent with multiple pendant thiol groups into an emulsion,thiol-disulfide interfacial crosslinking reactions lead to the formation of BSA encapsulated hollow capsules. The cleavage of disulfides on the membranes results in the degradation of hollow structures and the release of encapsulated protein molecules. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and confocal laser scanning microscopy were employed to characterize the hollow capsules. In comparison with native BSA, BSA molecules encapsulated in the hollow structures show higher catalytic efficiency due to higher local concentration of reactants in the structures. The membranes of the hollow capsules can efficiently protect the encapsulated BSA from hydrolysis by trypsin.

An Assay Study of Molecular Recognition of Amino Acids in Water: Covalent Imprinting of Cysteine

A novel synthetic N-(9-fluorenyl methoxy carbonyl)-L-Cysteine (Fmoc-Cys(SH)-OH) receptor was pre- pared by co-polymerizing (9-fluorenyl methoxy carbonyl)-S-(1-propene-2-thiol)-L-Cysteine (Fmoc-Cys(SCH2CHCH2)-OH) and a non-imprinted polymer prepared from 1-propene-1-thiol photo-chemically 15 h at room temperature and additional 3 h thermally at 80℃. Subsequently, disulfides were reduced with lithium aluminum hydride (LiAlH4) from imprinted polymers. The imprinted polymers selectively recognized Fmoc-Cys(SH)-OH with high binding constants in aqueous and protic solvents by thiol-disulfide exchange reactions. In order to estimate the covalent rebinding, particles were further extracted and disulfides reduced were estimated with the non-covalent recognized and covalently bounded analytes. From rebinding studies that were conducted, we observed that proved polymer particles could be reproducible and contain constant binding strengths and recognition properties. Furthermore, we proved that short incubation periods resulted in fast and efficient thiol-disulfide interchange reactions.

Synergistic control of dual cross-linking strategy toward tailor-made hydrogels

Simple, efficient and accurate controllable systems for materials are becoming more essential, in response to the explosively growing demands in the fields of chemistry and material science. Herein, tailored hydrogels are explored depending on synergistic regulation of p H-responsive chemical networks with an "on/off" function and physical networks with dynamic selfoptimized arrangement. Thiol-disulfide exchange reaction endows hydrogels with controlled architectures while hydrogen bondstrengthened 2-ureido-4[1H]-pyrimidinone(UPy) moieties contributes a significant increase in mechanical strengths. The integration of that dual cross-linking(DC) network ensures the hydrogels with customized structure and enhanced mechanical property. Such controllably strategy is universally applicable and will open a new avenue to flexibly fabricate desired hybrid hydrogels with distinctive features and functions for their potential applications.

Controlled Cross-linking Strategy for Formation of Hydrogels,Microgels and Nanogels

Hydrogels are a kind of unique cross-linking polymeric materials with three-dimensional networks. Various efforts have been devoted to manipulate the formation of functional hydrogels in situ and enrich the production of hydrogels, microgels and nanogels with improved modulation capacity. However, these methods always fail to tune the gel properties because of the difficulty in achieving the precise control of cross-linking extents once the gel formation is initiated. Therefore, the preparation of tailor-made hydrogels remains a great challenge. Herein, we summarize a controlled cross-linking strategy towards not only fabrication of hydrogels at nano-, micro-and macro-scales, but also achievement of controlled assembly of nanoparticles into multifunctional materials in macroscopic and microscopic scales. The strategy is conducted by controllably activating and terminating the disulfide reshuffling reactions of disulfide-linked core/shell materials with selective core/shell separation using system p H or UV triggers. So it provides a facile approach to producing hydrogels, hydrogel particles and nanoparticle aggregates with tunable structures and properties, opening up the design possibility, flexibility and complexity of hydrogels, microgels/nanogels and nanoparticle aggregates from nanoscopic components to macroscopic objects.

A Method to Accelerate the Gelation of Disulfide-crosslinked Hydrogels

A glutathione-disulfide-ended poly（ethylene glycol）（GSSG-PEG-GSSG） was designed. It is a much more efficient accelerator than glutathione disulfide（GSSG） for the gelation of an 8arm-PEG-SH polymer solution, and the gelation time can be tuned from hours to minutes at the physiological p H and temperature. A mechanism was proposed to explain the different behaviors of the GSSG and GSSG-PEG-GSSG gelation systems. Due to the ever-going thiol-disulfide exchange reaction, the thiol-disulfide hydrogels also showed interesting swelling behavior.