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Limited reports on the use of nanobodies (Nbs) in fluorescence polarization immunoassay (FPIA) aroused us to explore if the small size of Nbs is a drawback for the development of sensitive FPIA to small molecular compounds, particularly since FPIA is a technology strongly dependent on molecular weight. In the present work, three different molecular weight Nbs against 3-phenoxybenzoic acid (3-PBA), an exposure biomarker of pyrethroid insecticides, including bare Nbs (15 kDa), Nbs-Avidin (Nbs-AV, 60 kDa), and Nbs-Alkaline phosphatase (Nbs-AP, 130 kDa) were specifically generated to cover distinct regions on the polarization and molecular weight relationship curve for a fluorescein tracer. In competitive FPIA, similar half-maximal inhibitory concentrations (IC50) of 3-PBA of 16.4, 12.2, and 14.8 ng mL-1 were obtained for Nbs, Nbs-AV, and Nbs-AP, respectively, indicating that the size of Nbs in the range tested had no significant effect on the sensitivity of the resulting competitive FPIA. An IC50 of 20.2 ng mL-1 for an anti-3-PBA polyconal antibody based FPIA further demonstrated the performance of Nbs, which was comparable to that of traditional antibodies in FPIA. Spike-recovery studies showed good and reproducible recovery of 3-PBA in urine samples, demonstrating the applicability of Nb-based FPIA. Overall, our results show that Nb-based FPIA achieves sensitivity levels of FPIA based on conventional antibodies and further indicate that Nb absolutely meets the sensitivity requirement of FPIA.

A monoclonal antibody (mAb) was raised against tebuconazole (TEB) using a hapten where the p-chloro substituent of the TEB molecule was replaced with a long-chain carboxylic acid. The resulting mAb showed high sensitivity and specificity against TEB characterized by ELISA with a half-maximal inhibitory concentration (IC50) of 0.19 ng mL-1 and with cross-reactivity (CR) values below 0.01% to several analogues of triazole fungicides. On the basis of the mAb produced, a quantum dot beads-based fluorescence immunochromatographic test strip assay (QBs-FITSA) was developed for rapid and sensitive detection of TEB in agricultural product samples. The QBs-FITSA exhibited a linear detection range from 0.02 to 1.25 ng mL-1 with a limit of detection (LOD) of 0.02 ng mL-1. Furthermore, using produced mAb, multiple high-throughput rapid immunoassay formats could be achieved as a convenient monitoring tool for evaluation of human and environmental exposure to TEB.

Despite the breadth of scientific literature on micro- and nanoplastics (MNPs), a standardized procedure for detecting MNPs is still lacking so far, leading to incomparable results between published studies. This work innovatively proposed the combination of machine learning with advanced optical photothermal infrared (O-PTIR) spectroscopy to develop an efficient and reliable detection framework for MNPs. Spectra of MPs and non-MPs were first collected and inputted to build a classification model, based on which four important wavenumbers were selected. A simplified support vector machine (SVM) model was subsequently developed using the selected four wavenumbers. Good predictive ability was evidenced by a high accuracy of 0.9133. The developed method can improve speed as well as the reliability of results, having a great potential for routine analysis of MNPs, ultimately leading to the standardization of detection methods.

Single‐atom catalysts (SACs), with their well‐defined structure, serve as an efficient catalyst model for studying the structure‐performance relation in the electrocatalytic CO2 reduction reaction (CO2RR). Current CO2RR research primarily focus on the coordination interactions between metal single atoms and coordinated ligands, while the impact of the metal SAC′s microenvironment remains largely unexplored. Herein, we generate three microenvironments for a CoN4 ensemble by using different nitrogen sources to prepare Co SACs, i. e. pyridine‐type Co−N4 (Co−N4 SACPhen), the pyrrole‐type Co−N4 (Co−N4 SACDp) and the mixed‐type Co−N4(Co−N4 SACMm). It reveals that the Co−N4 SACPhen contributes to CO generation with 99.5 % selectivity at −0.76 vs RHE, whereas the Co−N4 SACDp accelerates a severe hydrogen evolution reaction. Experimental studies confirmed that the Co−N4 SACPhen possesses distinctive electrochemical properties and electronic structure, with the pyridine‐N being more conducive to electron accumulation and exhibited a higher electron delocalization, thereby promoting the generation of CO. This study deepens our understanding of the cobalt SAC′s microenvironment‘s influence on CO2RR. [ABSTRACT FROM AUTHOR]