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Light-responsive microgels are interesting colloidal systems with potential applications in the biotechnology and medicine. However, synthesis of light-responsive microgels with high loading of photoswitchable molecules is still very challenging. Herein we developed a new method to synthesize light and temperature dual-responsive spiropyran-modified poly(N -vinylcaprolactam) microgels. The novel and straightforward microgels synthesis route involved: a) synthesis of poly(N -vinylcaprolactam- co -vinylformamide) copolymers via RAFT polymerization followed by the hydrolysis to obtain primary amine groups, b) attachment of carboxyl-modified spiropyran molecules to polymer chains via coupling, and c) crosslinking of spiropyran-modified polymer chains in W/O miniemulsion to form microgels. Via this method, we successfully synthesized poly(N -vinylcaprolactam) microgels containing more than 10 mol% spiropyran. The reversible light responsiveness of the spiropyran-modified copolymers and microgels in aqueous solution, which originates from the spiropyran photoisomerization under irradiation with different wavelengths, was demonstrated by UV–Vis spectroscopy. Spiropyran-modified copolymers demonstrate shift of the lower critical solution temperature (LCST) due to the polarity change of spiropyran molecules under dark, UV and visible light. Surprisingly, dynamic light scattering (DLS) results show that the microgels based on the same copolymers are less affected by UV irradiation. Microgels are swollen in darkness when spiropyran molecules are in the polar, merocyanine form, and collapse after irradiation with visible light, due to the transformation of spiropyran to the relatively nonpolar, closed spirocyclic form. In addition, the spiropyran-modified microgels exhibit reversible temperature responsiveness by presenting a volume phase transition in water from a swollen state to a collapsed state with increasing temperature and the transition temperature decreased compared to the pristine microgels due to the hydrophobicity of spiropyran units. [ABSTRACT FROM AUTHOR]

A softer natural Pickering nanostabilizer, S -ovalbumin (S -OVA) was reported in this work, based on our previous researches about soft globular protein nanoparticles. Compared with native OVA, S -OVA has higher surface hydrophobicity, greater conformational flexibility and thinner tightly-bond water layer, which make it be unfolded more highly at the oil–water interface. However, S -OVA also possesses higher zeta-potential and thicker closely-surrounding water layer, offering it stronger electrostatic repulsion and steric hindrance between molecules and increased intramolecular cohesion. The improvements guarantee S -OVA undisintegrated particle structure and independent state on the interface and high refolding off the interface. The more flexible interior and firmer exterior together endow a higher softness to S -OVA. The HIPPE gels solely stabilized by S -OVA were fabricated using one-step shearing. These HIPPE gels own steady network structure mainly supported by bridging flocculation, strong self-supporting ability and moldability. The high storage stability and ability to inhibiting lipid oxidization provide the HIPPE gels an enormous potential in encapsulating and protecting volatile, easily-oxidized or dangerous organic liquids, during the storage and transportation. The attractive temperature responsiveness offers a high convenience to re-obtaining the organic liquids. And a re-encapsulation can be easily achieved via a re-shearing. The heat-enhanced gel intensity and moldability mean the HIPPE gels can be applied to produce dualistic gels or porous scaffolds with latent applications. These findings are helpful to explore more new Pickering stabilizers from the nature and extend the applications of HIPPEs in highly-demanded and high-tech industries. [ABSTRACT FROM AUTHOR]

By coupling two equivalents of N,N-diethyldithiocarbamoylmethylbenzoic acid succinimidyl ester with cystamine dihydrochloride, a disulfide-carrying compound (Cys-BDC) was prepared and used as iniferter (a compound which pursues initiation, chain transfer, and termination) in the telomerization of N,N-dimethylacrylamide and 3-acrylamidophenylboronic acid. The telomerization was carried out in the presence of N,N,N′,N′-tetraethylthiuram disulfide under photoirradiation at 365 nm. An aqueous solution of the telomer obtained showed responsiveness to both temperature and sugars as confirmed by the turbidity measurements. The telomer formed a self-assembled monolayer (SAM) on a gold surface as confirmed by both cyclic voltammetry (CV) and ellipsometry. The recognition of sugar residues by the telomer SAM constructed on the gold electrode was detected by the CV measurements. The usefulness of the iniferter to prepare various telomer-carrying SAMs with bio-related functions was strongly suggested. [Copyright &y& Elsevier]