The enzymatic antioxidant system (EAS) protects aerobic cells from oxidative stress. However, it is brittle and susceptible of inactivation of reactive oxygen species (ROS) immoderate production. Here, we demonstrated that MoS nanosheets (few-layer MoS), as a multifunctional nanozyme, possess intrinsic activity of mimicking enzymes of superoxide dismutases (SODs), catalases (CATs), and peroxidases (PODs) under physiological conditions (pH 7.4, 25 °C). Further, MoS nanosheets showed POD-like activity by transferring electrons instead of generating ROS. Similar to EAS, a defense termed nanozymatic antioxidant system (NAS) was developed by MoS nanosheets, for regulation of oxidative stress. Surprisingly, this NAS can effectively scavenge other free radicals including hydroxyl radicals (OH), nitrogen-centered free radicals (DPPH), and nitric oxide (NO). To evaluate these unique properties of MoS-based NAS in vivo, Escherichia coli ( E. coli), Staphylococcus aureus ( S. aureus), and A549 cell models were established, respectively. These results showed MoS nanosheets superiorly protect bacteria and cells against oxidative injury caused by HO. This work makes MoS nanosheets promising antioxidants in the pathological processes and expands their application in biocatalysis and nano-biomedicine.

MoSe2 nanosheets possess intrinsic peroxidase-like activity and are applied to H2O2 and xanthine detection with high sensitivity and selectivity.

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Combinatorial chemistry has opened a new realm of chemical entities in the search for novel therapeutics. Combinatorial chemistry is currently adding hundreds of thousands of compounds to similar numbers available from years of synthesis by medicinal chemistry. It is not unreasonable to expect that over the next several years, nearly a million compounds will be available for screening against each therapeutic target. The number of potential targets will also be increasing with the advances in genomics. With the increasing number of compounds to be screened against an increasing number of targets, it is becoming increasingly difficult and costly to obtain the required amounts of key biological material needed to screen these compounds. One obvious solution is to miniaturize the assays so that the biological reagent supply doesn't need to increase. To this end, we have developed an ultra-high throughput screening system comprised of a new plate design (9600-well), detection system, and liquid handling system. This new format is capable of performing assays in as little as 0.2 Al. The results obtained from this system compare favorably to those obtained in the standard 96-well format.