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Cryptomelane nanomaterials were synthesized by a facile redox–reflux method. The physicochemical properties of these composites were studied in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, laser Raman spectroscopy, thermogravimetric analysis (TGA), and N2 adsorption–desorption techniques. The catalytic activities of nanocryptomelane were evaluated through treatment of aqueous solutions that contained basic fuchsin. In the case of basic fuchsin, the catalytic activity of synthetic nanocryptomelane was much higher than that of natural cryptomelane. Moreover, synthetic nanocryptomelane shows high stability and recyclability, has a high specific surface area, and is rich in mesopores. It could be anticipated that the specific surface area of the material had an obvious effect on the degradation of basic fuchsin. Kinetic studies indicated that the reaction follows the Langmuir–Hinshelwood model. The catalytic activities were found to ...

Horseradish peroxidase (HRP)-mediated crosslinking of poly(amido amine) (PAA) copolymers was successfully applied in the preparation of in situ forming degradable hydrogels under physiological conditions. PAA copolymers containing different amounts of tyramine residues (termed as pAEEOL/TA) could be synthesized through Michael-type addition between methylenebisacryamide and amine mixture of 2-(2-aminoethoxy) ethanol and tyramine (TA). Depending on the amount of TA residue, the HRP, and H2O2 concentration, the gelation times could be varied from about 50 to 350 s. The swelling and degradation experiments indicated under physiological conditions the pAEEOL/TA-based hydrogels are completely degradable within 6–8 days. Rheological analysis revealed that storage modulus of the hydrogels increased from 2500 to 4100 Pa when increasing HRP concentrations. Importantly, pAEEOL/TA copolymers have low cytotoxicity. Moreover, NIH 3T3 (mouse embryonic fibroblast) cells exposed in the degradation products of pAEEOL/TA-based hydrogels retained high cell viability, implying that the hydrogels are cyto-biocompatible. In vitro release of methylene blue and IgG protein from pAEEOL/TA-based hydrogels could be effectively sustained by encapsulation of the drug in the hydrogels. The results indicate that HRP-crosslinked, degradable pAEEOL/TA-based hydrogels are promising for biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

TiO2 hollow spheres consisting of highly active {116} plane-oriented crystallites have been synthesized with a wide diameter distribution from 20 nm to over 5 μm via a facile emulsion method. The prepared hollow spheres possess large specific surface area (SBET = 104 m2/g) and mesopores (15.7 nm), which could be further modified by Pt doping. The mechanisms for hollow sphere formation and {116} plane orientation are discussed briefly. Moreover, compared with normal TiO2 hollow spheres, which usually exhibit uniform diameter distributions and no specific plane orientation, the typical TiO2 hollow spheres with and without Pt doping exhibit good photocatalytic activities for phenol degradation under visible and UV light irradiation. The wide diameter (i.e., curvature) distribution, high specific surface area, conduciveness to forming mesoporous structures, and exposed highenergy surfaces allow good molecular infiltration and adsorption as well as photoelectroactivity and make them attractive for light harvesting.

This paper demonstrates a novel strategy for site-selective cell adhesion and in situ cultivation of living cells, integrated with real-time monitoring of cellular small biomolecules based on dual functional protein microarrays. The protein microarrays have been produced on the superhydrophobic|philic Au-TiO2 micropatterns, through further modification of L-cysteine (Cys) and followed by successive immobilization of a model protein, cytochrome c (cyt c). Experimental results have revealed that the created cyt c microarrays play dual functions: one is employed as a robust substrate for site-selective cell adhesion and in situ cultivation of living cells, because the protein microarrays exhibit high selectivity and bioaffinity toward cells, as well as long biostability under cell culture condition up to 7 days. Meanwhile, the cyt c microarrays can also serve as sensing elements for hydrogen peroxide (H2O2) due to the inherent enzymatic activity of the heme center in cyt c. Direct electron transfer of cyt c has been enhanced at the Cys-modified Au-TiO2 (Au-TiO2/Cys) microarrays, and the electrochemical behavior can be tuned by varying the width and spacing of the microband arrays. Furthermore, cyt c is stably immobilized on the Au-TiO2/Cys microarrays and maintains its enzymatic activity after confined on the microarrays. Thus, the optimized cyt c microarrays show striking analytical performance for H2O2 determination, e.g., high sensitivity and selectivity, broad linear range from 10(-9) M to 10(-2) M, low detection limit down to 2 nM, and short response time within 5 s. As a result, the excellent analytical properties of the cyt c microarrays, as well as the characteristic of the protein microarrays themselves, including high selectivity, long biostability, and good bioaffinity, opens up a method for selective in situ cultivation of cells integrated with real-time detection of signaling biomolecules such as H2O2 released from living cells, which shows potential for physiological and pathological investigations.

Here, we report on a novel superoxide anion (O2(*-)) biosensor based on direct electron transfer of copper, zinc-superoxide dismutase (Cu, Zn-SOD) at zinc oxide nanodisks surface for in vivo tracking of O2(*-) in bean sprouts. Direct electron transfer of SOD is achieved at ZnO nanodisks film prepared by a one-step electrodeposited method, with a high heterogeneous electron rate constant of 17 +/- 2 s(-1). Spectroscopic data demonstrate that SOD strongly immobilized onto the nanostructured ZnO surfaces processes its inherent activity toward O2(*-) dismutation. A combination of the facilitated direct electron transfer and the bifunctional enzymatic catalytic activities of the SOD substantially provides a dual electrochemical approach to determination of O2(*-) with high selectivity, wide linear range, long stability, and good reproducibility. In particular, SOD adsorbed on the ZnO nanodisks film is capable of sensing O2(*-) cathodically at a very positive potential, 0 mV (vs Ag|AgCl), where the common interfering species such as hydrogen peroxide, uric acid, ascorbic acid, and 3,4-dihydroxyphenylacetic acid were effectively avoided. The excellent analytical performance of the present O2(*-) biosensor, combined with the remarkable characteristics of nanostructured ZnO films, such as biocompatibility, ease of preparation, and facile to miniaturize, paves an electrochemical way for reliable and durable in vivo determination of O2(*-) in bean sprouts.

This communication describes a novel and facile approach to direct electron transfer of copper, zinc–superoxide dismutase (Cu, Zn–SOD) at a physical vapor deposited zinc oxide (ZnO) nanoparticles surface. SOD exhibits quasi-reversible electrochemical behavior in phosphate buffer solution (PBS, pH 7.25), with apparent formal potential of 195.2 ± 4.6 mV vs. Ag|AgCl and high heterogeneous electron rate constant of 10.4 ± 1.8 s−1. Electrochemical results indicate that SOD stably immobilizes on the nanostructured ZnO film and processes its intrinsic enzymatic activity after adsorbed on ZnO nanoparticles. An electrostatic interaction between SOD with low isoelectric point (pI = 4.9) and ZnO nanoparticles with surface pKa of 9.35 is suggested to be the main force for the adsorption of SOD molecules on the nanostructured ZnO surface, and as a consequence, ZnO nanoparticles surface is favor for direct electron transfer of SOD. The enhanced electron transfer of SOD, together with intrinsic bidirectional catalytic activity of SOD toward superoxide anion (O2-) dismutation paves a way for the development of a third-generation O2- biosensor. Keywords: Electron transfer, Superoxide dismutase, ZnO nanoparticles, Superoxide anion, Physical vapor deposition

Based on the differences in titration spectra, mixtures of organic acids with similar p K a were determined simultaneously. Principal component regression calibration was used for the evaluation of titration spectra. The effects of differences in p K a and sampling interval of pH on accuracy were studied in detail. Combining precipitation and the acid–base reaction of organic acid, precipitation–acid–base titrimetry is proposed. The mixture of acids with almost the same p K a can be determined simultaneously and accurately only if their p K sp values are different. Synthetic mixtures of isomer of chlorobenzoic acid and homologue of phenol were determined simultaneously and acceptable results were obtained.

A novel and facile photoelectrochemical method has been developed to detect H(2)S in water samples with high sensitivity and selectivity. The protocol is based on the photocurrent generated by CdS nanoclusters which are deposited onto TiO(2) nanotubes exposing in CdSO(4) solution with the gradual addition of Na(2)S, with low-cost, environment-friendly, theoretical and technical simplicity. The developed method shows a very broad linear range from 10(-8) M to 10(-3) M and a low detection limit of 0.31 nM (9.92 ppt), far lower than the ceiling value in drinking water provided by WHO. Furthermore, the present method has been applied for determination of H(2)S in water samples. The concentrations of H(2)S in water samples determined by the present method are in a good agreement with those monitored by traditional spectrophotometry.

Purpose To determine whether deep anterior lamellar keratoplasty (DALK) using acellular glycerol-cryopreserved corneal tissue (GCCT) could prevent allograft rejection in high-risk corneas. Design Prospective, randomized, comparative study. Methods settings: The Eye Hospital, Wenzhou Medical College, Zhejiang, China. study population: All patients with herpes simplex virus keratitis, bacterial keratitis, fungal keratitis, or ocular burn, who were eligible as per study design, were invited to participate. observation procedures: According to randomized block design, all patients received either GCCT or fresh corneal tissue (FCT) during DALK. Best-corrected visual acuity (BCVA), slit-lamp microscopy, and in vivo confocal microscopy examinations at 1 week and 1, 3, 6, 12, and 24 months after surgery were analyzed. Kaplan-Meier survival analysis was used to evaluate graft survival rate. main outcome measures: Therapeutic success, 2-year rejection-free graft survival rate and 2-year graft survival rate, in vivo confocal microscopy results, BCVA, and endothelial cell density. Results Postoperative BCVA of 20/40 or better at the last follow-up visit was achieved in 57.6% (19/33) of eyes in the GCCT group and in 54.8% (17/31) of the FCT group. No graft rejection occurred in the GCCT group, while in the FCT group 10 episodes of stromal rejection developed in 7 eyes. Overall, the rejection-free graft survival rate at 2 years was significantly higher in the GCCT group as compared with the FCT group (100.0%, 78.8% respectively, P = .006). Conclusions Deep anterior lamellar keratoplasty using acellular glycerol-preserved cornea could prevent allograft rejection and promote graft survival rate in high-risk corneas.

A newly developed hydrogen peroxide selective membrane electrode using lettuce seed meal as source biocatalyst is described. This amperometric-based probe exhibits high biocatalytic activity, long lifetime and favorable selectivity for the measurement of hydrogen peroxide.

The WO 3 nanoparticles film is first employed as a support matrix for confining cytochrome c (cyt. c ), an excellent model for studying electron transfer between the redox enzymes and the electrode. The surface p K a of nanostructured WO 3 film is estimated to be ∼2.74 using electrochemical method. The present WO 3 surface with negative charge at the neutral solution is very benefit for the adsorption of cyt. c with positive charge and facilitates electron transfer of cyt. c . As a result, direct and fast electron transfer of cyt. c is realized at the nanostructured WO 3 surface with the redox formal potential ( E 0 ′) of −133.5 ± 1.7 mV ( n = 4) versus Ag/AgCl and heterogeneous electron transfer rate constant of 5.57 ± 0.54 s −1 . Experimental data indicate that cyt. c is stably confined onto the WO 3 nanoparticles film, possibly due to the electrostatic interaction between WO 3 nanostructures and cyt. c , and processes its enzymatic activity toward H 2 O 2 . Based on these results, the third-generation biosensor for H 2 O 2 is developed with high selectivity, free from not only common anodic interferences like ascorbic acid, uric acid, 3,4-dihydroxyphenylacetic acid, and so on, but also cathodic interference—O 2 . The remarkable analytical advantages, as well as the characteristic of WO 3 nanoparticles film such as biocompatibility, low-cost, and facile to miniature give a strong basis for continuous, on-line detection of H 2 O 2 under pathophysiological conditions.

The morphology-dependent electrochemistry and electrocatalytical activity of cytochrome c (cyt. c) were investigated at pyramidal, rodlike, and spherical gold nanostructures directly electrodeposited onto sputtered gold surfaces. Direct, reversible electron transfer of cyt. c, for the first time, was realized at nanorod-like and nanopyramidal gold surfaces without any mediators or promoters, while no redox reaction was observed at the nanospherical gold electrode. The electrochemical properties of cyt. c vary with the shape of gold nanostructures with respect to the reversibility of electrode reactions, kinetic parameters, the formal potentials (E0'), and charge-transport resistance (Rct), suggesting shape-dependent mechanisms for the electrode reactions of cyt. c. The experimental results manifest that cyt. c was stably immobilized on the nanostructured gold electrodes with different conformational changes of the heme microenvironment. Consequently, not only the electroactivity, but also the inherent biological activity of the immobilized cyt. c strongly depended on the shape of the electrode surfaces. The facilitated electron transfer combined with the intrinsic catalytical activity of cyt. c substantially constructed a third-generation H2O2 biosensor with high selectivity, quick response time, large linear range, and good sensitivity. The electrocatalytical activity of the immobilized cyt. c toward H2O2 was also found to be morphology dependent, and the linear range of H2O2 detection could be tuned by means of employing the nanostructured gold surfaces with different shapes.

The rough pyramidal gold nanostructures fabricated by a one-step, nontemplated, low-cost electrochemical deposition, combined with a perfluorodecanethiol coating and, more importantly, the very large fraction of air trapped into the gold film, create a super-amphiphobic surface.