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Recently, metal coordination has been widely utilized to fabricate high‐performance hydrogels, but conventional metal‐based hydrogels face some drawbacks, such as staining or acid lability. In the present study, a novel kind of colorless Zr(IV)‐crosslinked polyacrylamide/polyanionic cellulose (PAM/PAC) composite hydrogel with unique acid resistance was constructed via acrylamide polymerization in a PAC solution, followed by posttreatment in a zirconium oxychloride (ZrOCl₂) solution. The prepared gels were characterized in terms of Fourier transform infrared spectroscopy, scanning electron microscopy, and tensile and compressive mechanics, as well as acid resistance. Inside the gels, the synergistic action of hydrogen bonding and Zr(IV) coordination is responsible for their improved mechanical properties and good energy dissipation ability. One hydrogel with nearly 90 wt % of water content can sustain approximately 5 MPa of compression stress at 90% strain without damage. Both microscopic network structures and macroscopic mechanics demonstrate facile adjustability via changing the PAC dosages in polymerization and/or ZrOCl₂ concentrations in posttreatment. Moreover, the gels present unexpected acid resistance due to the strong Zr(IV) coordination with PAC, demonstrating their potential application as hydrogel electrolytes in supercapacitors. The current work provides a new approach to fabricate metal coordination‐based high strength, colorless hydrogels with acid resistance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 981–991

As a stand-alone therapy strategy may not be sufficient for effective cancer treatment and a combination of chemotherapy with other therapies is a main trend in cancer treatment. A combination of chemotherapy and photothermal therapy (PTT) is reported here to achieve the goal of cascade multistage cancer treatment. A thermally responsive amphiphilic copolymer is designed and then a CuS nanoparticles (NPs)-based carbon monoxide (CO) photoinduced release system and doxorubicin (Dox) are encapsulated to construct the nanomedicine. The large-sized nanomedicine can accumulate in tumors after long circulation in vivo and will generate heat to act as a photothermal therapeutic agent by near infrared (NIR) light. Moreover, synergically release of CO and Dox is achieved and acted as a sensitized chemotherapeutic agent. The combination of PTT and chemotherapy sensitization can effectively eliminate active tumor cells in the periphery of the tumor. CuS NPs are also released after the degradation of nanomedicine and small-sized CuS NPs possess better tumor penetration and achieve penetration-enhanced PTT by further NIR irradiation, thereby effectively eliminating tumor cells inside solid tumors. Hence, cascade multistage cancer treatment of "combined PTT and chemotherapy sensitization"-"penetration-enhanced PTT" is achieved, and tumor cells are comprehensively and effectively eliminated.

A series of polymer hydrogels based on 2-hydroxylethyl methacrylate and styrene were synthesized by bulk polymerization. The kinetic and thermodynamic swelling properties of these hydrogels were studied. The swelling mechanism of the hydrogels followed Fickian behavior. The diffusion coefficients, initial swelling rate, and maximum water uptake all decreased with the styrene content increasing because of the hydrophobicity of styrene. The swelling process was exothermic from 278 to 315 K, and the greater the styrene content was, the lower the enthalpy of mixing was in magnitude. The polymer–water interaction parameter, reflecting thermodynamic interactions, increased with increasing styrene content in the polymers. The negative values and trend of the actual partial molar enthalpy and entropy of dilution could be explained by the structuring of water through enhanced hydrogen bonding and hydrophobic interactions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Increasing evidence suggests that oxidative damage is associated with normal aging and several neurodegenerative diseases. Mild cognitive impairment (MCI), the phase between normal aging and early dementia, is a common problem in the elderly with many subjects going on to develop Alzheimer's disease (AD). Although increased DNA oxidation is observed in the AD brain, it is unclear when the oxidative damage begins. To determine if DNA oxidation occurs in the brain of subjects with MCI, we quantified multiple oxidized bases in nuclear and mitochondrial DNA isolated from frontal, parietal and temporal lobes and cerebellum of short post-mortem interval autopsies of eight amnestic patients with MCI and six age-matched control subjects using gas chromatography/mass spectrometry with selective ion monitoring. We found statistically significant elevations (p

Cellulose triacetate (CTA) nanofiber nonwoven mats were continuously electrospun by using mixed solvent of DMSO/chloroform system. The size and morphology of CTA nanofibers were investigated. It was found that CTA fibers with diameters in the range of 98 nm–1.81 μm were obtained from 8 wt % CTA solutions in 1 : 1, 3 : 2, 2 : 1, 3 : 1, 5 : 1 and 7 : 1 (v/v) DMSO/chloroform. The average diameter of CTA nanofiber was decreased and size distribution was narrowed with increasing the DMSO content in the mixed solvent. Smooth and uniform nanofibers with mean diameters of about 260 nm could be obtained from a solution of CTA in the binary system DMSO/chloroform 5 : 1(v/v) at a polymer concentration of 8 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40373.

The activity of immobilized subtilisin BPN' on pure cellulose-based membrane support was investigated using site-directed and random immobilization approaches. The catalytic activity of site-directed immobilized subtilisin on pure cellulose fiber-based materials was found to be 81% of that in homogeneous solution, while that of randomly immobilized subtilisin was 27%. Pure cellulose membrane supports provided large surface areas for high enzyme loading without diffusional limitations. The activity of immobilized subtilisin on pure cellulose support was more than twice that on a modified polyether sulfone (MPS) membrane, which was attributed to the higher hydrophilicity of cellulose. Immobilized subtilisin maintained its initial activity for 14 days at 4 degrees C and 7 days at 24 degrees C. The immobilized enzyme could resist higher temperature and operate over a wider range of pH without loss of activity. This study showed that pure cellulose fiber-based membranes are well suited for enzyme immobilization and biocatalysis.

Kinetic comparisons have been made between a randomly immobilized and a site-specifically immobilized subtilisin BPN' on microfiltration membranes of varying hydrophilicities in both aqueous and organic media. Site-directed mutagenesis was employed to introduce a single cysteine into the amino acid sequence of subtilisin at a location away from the active site. Immobilization of this mutant enzyme was then carried out using the single cysteine residue to orient the active site of the enzyme away from the membrane surface. Kinetic comparison of the immobilized mutant enzyme with the randomly immobilized wild-type enzyme in aqueous media showed an activity enhancement on both hydrophilic silica-containing and hydrophobic poly(ether)sulfone membranes. Higher loading efficiencies were observed for the site-directed enzyme on immobilization. Optimal enzyme loading values were calculated for the randomly immobilized enzyme. An enhancement of activity was also observed for the site-directed immobilized systems using nearly anhydrous hexane as the solvent.