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This work proposed a simple and ultrasensitive nanozyme-based immunoassay on a filtration device for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (NP). Gold core porous platinum shell nanoparticles (Au@Pt NPs) were synthesized with high catalytic activity to oxidize 3,3′,5,5′-tetramethylbenzidine, leading to an oblivious color change. The filtration device was designed based on the size difference of magnetic beads, filter membrane pore, and Au@Pt NPs. A simple, rapid, and consistent washing procedure can be performed with the help of a plastic syringe. This detection method could realize the quantitative detection of SARS-CoV-2 NP within 80 min for point-of-care needs. The limit of detection for the SARS-CoV-2 antigen was 0.01 ng/mL in buffer. The coefficients of variation of the assay were 1.78% for 10 ng/mL SARS-CoV-2 antigen, 2.03% for 1 ng/mL SARS-CoV-2 antigen, and 2.34% for the negative sample, respectively. The specificity of the detection platform was verified by the detection of various respiratory viruses. This simple and effective detection system was expected to promote substantial progress in the development and application of virus immunodetection technology.

Timely, accurate, and rapid diagnosis of SARS-CoV-2 is a key factor in controlling the spread of the epidemic and guiding treatments. Herein, a flexible and ultrasensitive immunochromatographic assay (ICA) was proposed based on a colorimetric/fluorescent dual-signal enhancement strategy. We first fabricated a highly stable dual-signal nanocomposite (SADQD) by continuously coating one layer of 20 nm AuNPs and two layers of quantum dots onto a 200 nm SiO2nanosphere to provide strong colorimetric signals and enhanced fluorescence signals. Two kinds of SADQD with red and green fluorescence were conjugated with spike (S) antibody and nucleocapsid (N) antibody, respectively, and used as dual-fluorescence/colorimetric tags for the simultaneous detection of S and N proteins on one test line of ICA strip, which can not only greatly reduce the background interference and improve the detection accuracy but also achieve a higher colorimetric sensitivity. The detection limits of the method for target antigens via colorimetric and fluorescence modes were as low as 50 and 2.2 pg/mL, respectively, which were 5 and 113 times more sensitive than those from the standard AuNP-ICA strips, respectively. This biosensor will provide a more accurate and convenient way to diagnose COVID-19 in different application scenarios.

Eleganketal A (1), a naturally occurring aromatic polyketide possessing a rare highly oxygenated spiro[isobenzofuran-1,3′-isochroman] ring system, was isolated from the fungus Spicaria elegansKLA03 by culturing it in a modified mannitol-based medium. The structure of 1including the absolute configuration was determined by combining spectroscopic analysis, synthesis of the racemic permethylated analogue, chiral-phase HPLC separation, and TDDFT-ECD analysis.

Different culture conditions directed by the OSMAC one strainmany compounds approach drastically modified the metabolites of the fungus Spicaria elegans, which yielded the novel spicochalasin A 1, five new aspochalasins M–Q 2–6, and two known aspochalasins 7and 8. The gross structures of 1–6were elucidated by 1D and 2D NMR and MS methods, and their absolute configurations were determined by Xray diffraction and the Mosher ester method. Spicochalasin A 1 has a unique pentacyclic system and was found to be moderately cytotoxic towards human leukemic HL60 cells with an IC50value of 19.9 μM.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

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