Nanozyme antibacterial agents with high enzyme-like catalytic activity and strong bacteria-binding ability have provided an alternative method to efficiently disinfect drug-resistance microorganism. Herein, the carbon nitride quantum dots (CNQDs) nanozymes with high nitrogen vacancies (NVs) were mass-productively prepared by a simple ultrasonic-crushing method assisted by propylene glycol. It was found that the NVs of CNQDs were stemmed from the selective breaking of surface N-(C)₂ sites, accounting for 6.2%. Experiments and density functional theory (DFT) simulations have demonstrated that the presence of NVs can alter the local electron distribution and extend the π-electron delocalization to enhance the peroxidase-like activity. Biocompatible CNQDs could enter inside microorganisms by diffusion and elevate the bacteria-binding ability, which enhanced the accurate and rapid attack of ·OH to the microorganisms. The sterilization rate of CNQDs against Gram-negative bacteria (E. coli), Gram-positive bacteria (S. aureus, B. subtilis), and fungi (R. solani) reaches more than 99%. Thus, this work showed great potential for engineered nanozymes for broad-spectrum antibacterial in biomedicine and environmental protection.

Surface Lewis acid-base sites in crystal structure may influence the physicochemical properties and the catalytic performances in nanozymes. Understanding the synergistic effect mechanism of Co₃O₄ nanozymes towards substances (3, 3o, 5, 5o-tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂)) induced by surface Lewis acid-base sites is important to enhance the efficiency for peroxidase-like reaction. Herein, ultrathin porous Co₃O₄ nanosheets with abundant Lewis acid-base sites were prepared by sodium borohydride (NaBH₄) reduction treatment, which exhibited high-efficiency peroxidase-like activity compared with original Co₃O₄ nanosheets. The Lewis acid-base sites for ultrathin porous Co₃O₄ nanosheets nanozyme were owing to the coordination unsaturation of Co ions and the formation of defect structure. Ultrathin porous Co₃O₄ nanosheets had 18.26-fold higher catalytic efficiency (1.27×10^-2 s^-1dmM^-1) than that of original Co₃O₄ (6.95×10^-4 s^-1dmM^-1) in oxidizing TMB substrate. The synergistic effect of surface acid and base sites can enhance the interfacial electron transfer process of Co₃O₄ nanosheets, which can be a favor of absorption substrates and the generation of reactive intermediates such as radicals. Furthermore, the limit of detection of hydroquinol was 0.58 μM for ultrathin porous Co₃O₄ nanosheets, 965-fold lower than original Co₃O₄ (560 μM). Besides, the linear range of ultrathin porous Co₃O₄ nanosheets was widely with the concentration of 5.0-1, 000 μM. Colorimetric detection of hydroquinol by agarose-based hydrogel membrane was provided based on excellent peroxidase-like properties. This study provided insights into designing high-performance nanozymes for peroxidase-like catalysis via a strategy of solid surface acid-base sites engineering.

The sensitive and on-site detection of inorganic explosives has raised serious concerns regarding public safety. However, high stability and non-volatility features currently limit their rapid on-site detection. Surface-enhanced Raman spectroscopy (SERS) is emerging as a powerful technique for the trace-level detection of different molecules. Plasmonic Ag nanowires were produced by a hydrothermal synthesis method using polyvinylpyrrolidone (PVP) as a negatively charged stabilizer. Here, we report a rapid detection method for inorganic explosives based on a simple surface swab with a positively charged diethyldithiocarbamate-modified Ag nanowire membrane coupled with SERS. This membrane, serving as an excellent SERS substrate with high uniformity, stability, and reusability, can capture both typical oxidizers in inorganic explosives and organic nitro-explosives, via electrostatic interaction. The detection level of perchlorates (ClO₄^-), chlorates (ClO₃^-), nitrates (NO₃^-), picric acid, and 2, 4-dinitrophenol is as high as 2.0, 1.7, 0.1, 45.8, and 36.6 ng, respectively. In addition, simulated typical inorganic explosives such as black powders, firecrackers, and match heads could also be detected. We believe that this membrane represents an attractive alternative for rapid on-site detection of inorganic explosives with high efficiency.

A facile one-pot microwave irradiation reduction route has been developed for the synthesis of highly luminescent CdTe quantum dots using Na₂TeO₃ as the Te source in an aqueous environment. The synthesis parameters of this simple and rapid approach, including the reaction temperature and time, the pH of the reaction solution and the molar ratio of the 3-mercaptopropionic acid (MPA) stabilizer to Cd²⁺, have considerable influence on the particle size and photoluminescence quantum yield of the CdTe quantum dots. The photoluminescence quantum yield of CdTe quantum dots prepared using relatively short reaction times (10–40 min) reached 40%–60% (emission peaks at 550–640 nm). Furthermore, the resulting products could be used as fluorescent probes to detect Hg²⁺ ions in aqueous media. The response was linearly proportional to the concentration of Hg²⁺ ion in the range 8.0×10^-9 mol/L to 2.0×10^-6 mol/L with a detection limit of 2.7×10^-9 mol/L.