A general strategy for the fabrication of mechanically robust ionogels by hydrogen bonding between elastomers and [NTf2]-based ILs is demonstrated.

Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here.

Hypervirulent variants of Klebsiella pneumoniae (hvKp) that cause invasive community-acquired pyogenic liver abscess (PLA) have emerged globally. Little is known about the virulence determinants associated with hvKp, except for the virulence genes rmpA/A2 and siderophores (iroBCD/iucABCD) carried by the pK2044-like large virulence plasmid. Here, we collected most recent clinical isolates of hvKp from PLA samples in China, and performed clinical, molecular, and genomic sequencing analyses. We found that 90.9% (40/44) of the pathogens causing PLA were K. pneumoniae. Among the 40 LA-Kp, K1 (62.5%), and K2 (17.5%) were the dominant serotypes, and ST23 (47.5%) was the major sequence type. S1-PFGE analyses demonstrated that although 77.5% (31/40) of the LA-Kp isolates harbored a single large virulence plasmid varied in size, 5 (12.5%) isolates had no plasmid and 4 (10%) had two or three plasmids. Whole genome sequencing and comparative analysis of 3 LA-Kp and 3 non-LA-Kp identified 133 genes present only in LA-Kp. Further, large scale screening of the 133 genes in 45 LA-Kp and 103 non-LA-Kp genome sequences from public databases identified 30 genes that were highly associated with LA-Kp, including iroBCD, iucABCD and rmpA/A2 and 21 new genes. Then, these 21 new genes were analyzed in 40 LA-Kp and 86 non-LA-Kp clinical isolates collected in this study by PCR, showing that new genes were present 80–100% among LA-Kp isolates while 2–11% in K. pneumoniae isolates from sputum and urine. Several of the 21 genes have been proposed as virulence factors in other bacteria, such as the gene encoding SAM-dependent methyltransferase and pagO which protects bacteria from phagocytosis. Taken together, these genes are likely new virulence factors contributing to the hypervirulence phenotype of hvKp, and may deepen our understanding of virulence mechanism of hvKp.

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A spiropyran-based amphiphilic random copolymer was synthesized and self-assembled into photo-, pH-, and thermo-responsive micellar nanoparticles. The triple-stimuli triggered morphological changes of the nanoparticles were revealed by TEM and DLS. Highly efficient controlled release of encapsulated molecules, coumarin 102, from the nanoparticles under stimulation of UV light, acid and the combined stimuli could be realized.

Here a near-infrared light and pH responsive nanocomposite comprising spiropyran-functionalized amphiphilic polymers and upconversion nanoparticles (UCNPs) is reported, which is prepared through the self-assembly of the amphiphilic polymers and the encapsulation of the UCNPs in the core of the self-assemblies. Upon near-infrared light irradiation, the upconversion fluorescence can induce the hydrophobic spiropyran to be isomerized to the hydrophilic merocyanine and disrupt the spherical morphology of the nanocomposites. Meanwhile, at low pH, the hydrophobic spiropyran can be also protonated to become hydrophilic merocyanine, and the self-assemblies are swollen. Model molecules, hydrophobic Coumarin 102, are demonstrated to be released from the nanocomposites triggered by the near-infrared light and acidic pH. In addition, the cytotoxicity of the nanocomposites loaded with anticancer drugs Doxorubicin on cancer cells indicates that the loaded drugs can be released and kill the cells effectively and the efficiency can be enhanced significantly upon near-infrared light irradiation.

Here we report a novel quadruple-stimuli-responsive block copolymer nanocarrier sensitive to pH, temperature, light, and reducing agent. The well-defined amphiphilic diblock copolymer poly(2-nitrobenzyl methacrylate)-SS-poly(dimethylaminoethyl methacrylate) (PNBM-SS-PDMAEMA) was synthesized via two steps of atom transfer radical polymerization (ATRP). In aqueous solution, the diblock copolymer self-assembled into nanoparticles consisting of a light-responsive hydrophobic PNBM core, a pH- and temperature-responsive hydrophilic PDMAEMA corona, and a redox-sensitive disulfide linker. The multi-stimuli-responsive behaviors of the block copolymer assemblies were revealed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The release of encapsulated molecules from the polymeric nanocarriers could be enhanced under combined stimulation. The prepared multi-stimuli-responsive nanocarriers may offer significant opportunities in diverse applications in the fields of nanotechnology and biotechnology for controlled release.

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