A new surface-enhanced Raman spectroscopy (SERS) biosensor of Graphene@Ag-MLF composite structure has been fabricated by loading AgNPs on graphene films. The response of the biosensor is based on plasmonic sensing. The results showed that the enhancement factor of three different spores reached 10 7 based on the Graphene@Ag-MLF substrate. In addition, the SERS performance was stable, with good reproducibility (RSD<3%). Multivariate statistical analysis and chemometrics were used to distinguish different spores. The accumulated variance contribution rate was up to 96.35% for the top three PCs, while HCA results revealed that the spectra were differentiated completely. Based on optimal principal components, chemometrics of KNN and LS-SVM were applied to construct a model for rapid qualitative identification of different spores, of which the prediction set and training set of LS-SVM achieved 100%. Finally, based on the Graphene@Ag-MLF substrate, the LOD of three different spores was lower than 10 2 CFU/mL. Hence, this novel Graphene@Ag-MLF SERS substrate sensor was rapid, sensitive, and stable in detecting spores, providing strong technical support for the application of SERS technology in food safety. Graphical abstract
Introduction The incidence of inflammatory bowel disease (IBD) has been increasing year by year in recent years. Flavonoids are the main components of mulberry leaves exerting anti-inflammatory effects and have potential applications in drug screening for IBD treatment. Enzymatic hydrolysis can enhance the bioavailability and activity of flavonoid glycosides. No relevant reports on the potentiation of mulberry leaf flavonoids (MLF) after deglycosylation have been retrieved. Methods An enzymatic method was used to prepare enzymatic hydrolysates of MLF (EMLF). The protective effect of EMLF on zebrafish with IBD was evaluated by observing zebrafish intestinal length and width, intestinal histopathological morphology, as well as neutrophil and goblet expression. Network pharmacology and metabolomics were performed to explore the mechanism of action of EMLF against IBD. Finally, the mechanism of EMLF against IBD was validated using Western Blot and real-time quantitative polymerase chain reaction (RT-qPCR). Results The EMLF was successfully prepared by hydrolyzing MLF with snailase for the first time, and the anti-inflammatory effect of EMLF was clarified to be superior to that of MLF in IBD zebrafish. The network pharmacology and metabolomics studies showed that the mechanism of EMLF for IBD may be related to regulation of purine metabolic pathway. The expression levels of adenosine deaminase (ADA), critical targets in purine metabolism, were significantly down-regulated, while the expression of adenine phosphoribosyltransferase (APRT) and xanthine dehydrogenase (XDH) was significantly increased when compared with the TNBS group. Conclusion The results suggested that enzymatic deglycosylation is an effective measure to enhance the anti-inflammatory activity of MLF, which provides referable ideas and methods for the deep processing and utilization of natural drug resources.
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