Search

Because of the problem of bacterial resistance, inorganic antibacterial materials represented by metallic nanomaterials have attracted attention for their antimicrobial properties. However, their antibacterial efficiency and safety need to be improved, and the cost of preparation needs to be reduced. Here a novel and highly stable cysteine-directed silver-copper composite nanoclusters hydrogel (AgCu NCs hydrogel) was prepared by employing a simple and green UV photoreduction one-pot method. The optical properties, structure and synthesis principle of AgCu NCs hydrogel were characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), and X-Ray photoelectron spectroscopy (XPS), respectively. The antibacterial activities of AgCu NCs hydrogel against Esherichia coli (E.coli) and Staphylococcus aureus (S.aureus) were evaluated using zones of inhibition, minimum inhibitory concentrations (MIC), minimum bactericidal concentration (MBC), and growth curves. The AgCu NCs hydrogel shows highly synergistic antibacterial performance toward both E.coli and S.aureus with the MIC of 0.781 μg/mL, 3.125 μg/mL and MBC of 12.5 μg/mL, 100 μg/mL, respectively. In addition, due to the good biocompatibilities, the AgCu NCs hydrogel has a good therapeutic effect on burn wounds. It will eventually become a new, low-cost, and highly effective antibacterial medical dressing.

A high-performance electrochemical H2O2 sensor was prepared by constructing multiple interfaces using platinum nanoparticles (Pt NPs), ferumoxytol (Fer) and reduced graphene oxide (rGO) on a glassy carbon electrode (GCE). The morphology of Fer/rGO and Fer/rGO-Pt was characterized by field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cyclic voltammetry and chronoamperometry were adopted to characterize the electrochemical properties of the sensor. Because of the synergistic catalytic effect of the compositions (rGO, Fer and Pt NPs) on the multiple interfaces, the sensor exhibits particularly high electrocatalytic activity toward the reduction of H2O2 with a low detection limit (~0.38 μM), a linear range (0.0004–0.01, 0.0075–4.3 and 4.9–10.8 mM), and a high sensitivity (340 μA mM−1 cm−2, n = 4) operated at a typical working voltage of +0.1 V (vs. Ag/AgCl). The electrode is selective and long-term stable. It was successfully applied to the determination of H2O2 in (spiked) milk samples.

A method is described for fluorometric determination of cysteine (Cys) and glutathione (GSH), either in solution by using a fluorescence spectrometer, or by using a paper-based test with visual observation. The method is based on the finding that the yellow fluorescence of the gold/silver nanoclusters (AuAg NCs), with excitation/emission maxima of 358/574 nm, is quenched by Cys and GSH via NCs aggregation. The method is selective for Cys and GSH. The limits of detection for both Cys and GSH are 0.74 nM in solution state and 5.0 μM on paper-based test. Response is linear in the range from 2.3 nM to 110 μM and from 2.3 nM to 63 μM in solution for Cys and GSH, respectively. The method is not interfered by other amino acids even if their concentrations are 10 times higher. It was successfully applied to the determination of Cys in spiked serum samples.