A novel and efficient light-controlled colorimetric assay for the quantification and detection of nitroreductase (NTR) was constructed based on p-aminophenol (pAP)-catalyzed and nicotinamide adenine dinucleotide (NADH)-mediated generation of AgNPs. Due to the hydrolysis of p-nitrophenol by NTR in the presence of NADH, the hydrolysis product can be used as a catalyst to catalyze the reduction of Ag+ by NADH under the light. As the concentration of NTR increases, the value of absorbance at ca. 400 nm (A400) decreases and the color of the solution turns from brown to bright yellow. A linear correlation was obtained between A400 and the NTR concentration in the range from 1–50 μg mL−1 and the limit of detection (LOD) is 0.27 μg mL−1. The detection system does not respond to other common biological molecules due to the specificity of enzymes and the effect of the nitroreductase inhibitor on the NTR activity was also tested. Finally, we applied the assay to determine NTR in human serum samples by spiking different concentrations of NTR with a recovery of 85.2%–92.5%.
Background Acetaminophen, a widely used analgesic and antipyretic drug, has become a significant aquatic micro-pollutant due to its extensive global production and increased consumption, particularly during the COVID-19 pandemic. Its high-water solubility leads to its pervasive presence in wastewater treatment plants (WWTPs), posing substantial risks to the environment and human health. Biological treatment is one of the promising approaches to remove such pollutants. Although previous studies have isolated acetaminophen-degrading pure cultures and proposed catabolic pathways, the interactions between microbiotas and acetaminophen, the distribution feature of acetaminophen degradation genes, and the gene-driven fate of acetaminophen in the real-world environment remain largely unexplored. Results Among the water samples from 20 WWTPs across China, acetaminophen was detected from 19 samples at concentrations ranging from 0.06 to 29.20 nM. However, p -aminophenol, a more toxic metabolite, was detected in all samples at significantly higher concentrations (23.93 to 108.68 nM), indicating the presence of a catabolic bottleneck in WWTPs. Metagenomic analysis from both the above 20 samples and global datasets revealed a consistently higher abundance of initial acetaminophen amidases compared to downstream enzymes, potentially having explained the reason for the bottleneck. Meanwhile, a close correlation between initial amidases and Actinomycetota revealed by genome-based taxonomy suggests a species-dependent degradation pattern. Additionally, a distinct amidase ApaA was characterized by newly isolated Rhodococcus sp. NyZ502 (Actinomycetota), represents a predominant category of amidase in WWTPs. Significant phylogenetic and structural diversity observed among putative amidases suggest versatile acetaminophen hydrolysis potential in WWTPs. Conclusions This study enhances our understanding of acetaminophen’s environmental fate and highlights the possible occurrence of ecological risks driven by imbalanced genes in the process of acetaminophen degradation in global WWTPs. Your browser is not supporting the HTML5
In this work, Cu nanosphere-anchored Cu-based MOF derivants were synthesized by high-temperature calcination using Cu(BDC) as precursors and then combined with gold nanoparticles to give AuNPs/Cu/C composites. The proposed materials were characterized by SEM, XRD, XPS, FTIR, and EIS. Based on these composites, a sensor was constructed, which showed good electrocatalytic activities to the redox of acetaminophen (PA) and P-aminophenol (4-AP) and could be used to detect them simultaneously. Under optimal experimental conditions, the linear ranges for detection of PA and 4-AP were 0.50–150.00 and 0.50–120.00 μM with the detection limits of 0.056 and 0.084 μM, respectively. Thanks to the hierarchical and porous structural characteristics of the Cu/C material and its synergistic effect with AuNPs, it shows good sensing performance in the simultaneous detection of PA and 4-AP. The sensor has wider linear ranges, lower detection limits, good selectivities, and higher accuracies with potential environmental detection application prospects.
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