Nanomaterials serving as artificial enzymes of the new generation (nanozymes), exhibit enhanced catalytic performance, excellent stability, low cost of production, and other associated properties of nanoparticles. This emerging field of nanozymes has broad-spectrum potential applications in the bridging area nanotechnology and biomedicine. Among metal-based nanozymes, bimetallic nanoparticles have been found to show enhanced catalytic performance and display ability to catalyze multistep reactions typically not observed in their monometallic counterparts. Herein, we report the synthesis of CuÀ Pt based bimetallic nanoalloys coated with a nonionic surfactant polyoxyethylene cholesteryl ether. The characterization data sug-gest that the developed nanoalloys have an almost uniform distribution of Cu and Pt (1:1) elements; therefore, this novel technique could be used for the large-scale synthesis of CuÀ Pt based nanozymes in a one-step procedure. Further investigations showed that these bimetallic nanoalloys possess excellent biological oxidase enzyme-like activity and the catalytic activity could be performed at harsh conditions of pH and temperature. Oxidase activity of CuÀ Pt nanoalloys was utilized for the sensitive detection of ascorbic acid in the sub-micromolar concentration range. Supplementing ATP in the oxidase reaction, the nanozyme showed enhanced catalytic activity, which was used for the detection of human liver cells.

Specific reactivity of cerium oxide nanoparticles with phosphate ions was used to design a novel antibacterial system. The redox sensitivity of cerium oxide nanoparticles (CeNPs) was used to irreversibly scavenge phosphate ions from the microbial growth media resulting in nutrient starvation in microbes. Cerium oxide nanoparticles surface was engineered with different ratios of (Ce (+3)/Ce (+4)) cerium oxidation states and the effect of surface oxidation states was evaluated on the antibacterial activity. The nutrient depletion-based antibacterial activity is demonstrated selectively by CeNPs with higher Ce (+3)/Ce (+4) ratio on the surface. The surface chemistry of Ce (+3) is altered in the presence of phosphate, resulting in the irreversible formation of surface cerium phosphates leading to the loss of its intrinsic superoxide dismutase (SOD) activity. It is hypothesized that nutrient starvation by Ce (+3) leads to oxidative stress in microbes which is not neutralized by the altered surface chemistry of CeNPs with high (Ce (+3)/Ce (+4)) ratio. On the contrary, CeNPs with higher (Ce (+4)/Ce (+3)) ratio did not show any reactivity towards phosphate, thus depicted no antibacterial activity, confirming the hypothesis that surface chemistry, rather than size or morphology-dependent toxicity is the main reason for the observed antibacterial activity of CeNPs.

Insects hold considerable ecological and agricultural importance making it vital to understand the factors impacting their reproductive output. Environmental stressors are examples of such factors which have a substantial and significant influence on insect reproductive fitness. Insects are also ectothermic and small in size which makes them even more susceptible to environmental stresses. The present study assesses the consequence of desiccation on the mating latency and copulations duration in tropical Drosophila melanogaster. We tested flies for these reproductive behavioral parameters at varying body water levels and with whole metabolome analysis in order to gain a further understanding of the physiological response to desiccation. Our results showed that the duration of desiccation is positively correlated with mating latency and mating failure, while having no influence on the copulation duration. The metabolomic analysis revealed three biological pathways highly affected by desiccation: starch and sucrose metabolism, galactose metabolism, and phenylalanine, tyrosine and tryptophan biosynthesis. These results are consistent with carbohydrate metabolism providing an energy source in desiccated flies and also suggests that the phenylalanine biosynthesis pathway plays a role in the reproductive fitness of the flies. Desiccation is a common issue with smaller insects, like Drosophila and other tropical insects, and our findings indicate that this lack of ambient water can immediately and drastically affect the insect reproductive behaviour, which becomes more crucial because of unpredictable and dynamic weather conditions.

Growing summer season, increased anthropogenic activities poses a continual challenge to resident species. Ectotherms like insects are especially vulnerable to rapid climatic changes. High-altitude tropical insect populations have been rarely examined for their responses to high-temperature. We exposed a tropical highland out-bred population of Drosophila melanogaster from the Himalayas to growing summer conditions in outdoor mesocosm units. Population response to thermal changes was tracked over ninety days at phenotypic and genotypic level. Whole genomic resequencing data suggested a clear seasonal allelic shift. Interestingly, the general heat responsive genes were missing in the summer due to monsoon allele shift; an atypical response noted for high-altitude populations. Instead, candidates involved in kinases and phosphorylation emerged as key players. Heat-knockdown time decreased over time indicating a limited ability to handle increasing temperature. Merging data from both allelic shifts and heat-knockdown time indicated a limited capacity for high-altitude insects in handling climate warming.

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