Putrescine and cadaverine are biogenic amines that serve as potential biomarkers for several types of cancers and monitoring food quality. Electrochemical sensing of putrescine and cadaverine by non-enzymatic routes remains a challenge because of their inertness at unmodified electrode surfaces and hence a liquid-liquid interface strategy has been employed for their detection. In the present study, electrochemical sensing of cadaverine and putrescine has been demonstrated by simple and facilitated ion-transfer processes using a liquid-liquid microinterface supported by a microcapillary. A microinterface was constructed in different configurations by varying the aqueous phase composition in the absence and presence of dibenzo-18-crown-6, and the ion-transfer ability of putrescine and cadaverine was studied in these configurations. A peak shaped voltammogram was observed in the backward scan, due to the linear diffusion of putrescine and cadaverine from the organic to the aqueous phase. The detection ability in the presence of dibenzo-18-crown-6 was observed in the concentration ranges of 0.25-25 μM and 0.25-40 μM for putrescine and cadaverine with detection limits of 0.11 and 0.17 μM respectively. In the presence of dibenzo-18-crown-6, the electrochemical sensing of putrescine and cadaverine was more pronounced compared to the simple ion-transfer process.The 20S proteasome enzyme complex is involved in the proteolytic degradation of misfolded and oxidatively damaged proteins and is a focus of medical research for the development of compounds with pharmaceutical properties, which are active in cancer cells and/or neurodegenerative diseases. The present study aims to develop a biosensor for investigating the 20S proteasome activity and inhibition by means of electrochemical methods. The 20S proteasome is best immobilized at the electrode surface through bio-affinity interactions with antibodies that target different subunits on the 20S proteasome, enabling the investigation of the effect of an enzyme's orientation on biosensor response. The enzymatic activity is analyzed by fixed potential amperometry with the highest sensitivity of 24 μA cm-2 mM-1 and a LOD of 0.4 μM. The detection principle involves the oxidation of an electroactive probe that is released from the enzyme's substrates upon proteolysis. The most sensitive biosensor is then used to study the multicatalytic activity of the 20S proteasome, i.e. the caspase-, trypsin- and chymotrypsin-like activity, by analyzing the biosensor's sensitivity towards different substrates. The behavior of the immobilized 20S proteasome is investigated as a function of substrate concentration. The kinetic parameters are derived and compared with those obtained when the enzyme was free in solution, with K0.5 values being one to two orders of magnitude lower in the present case. Two 20S inhibitors, epoxomicin and bortezomib, are investigated by analyzing their influence on the 20S biosensor response. The proposed analytical method for proteasome activity and inhibitor screening has the main advantage of being cost-effective compared to the ones typically employed.Insulin resistance has become a worldwide nutrition and metabolic health problem due to the lack of effective protective agents. Laminaria japonica is a well-known marine vegetable. Purified Laminaria japonica polysaccharide (LJP61A) can inhibit atherosclerosis in high-fat-diet (HFD)-fed mice via ameliorating insulin resistance. In this study, we aimed to clarify the mechanism by which LJP61A ameliorates HFD-induced insulin resistance. The results indicated that HFD-induced insulin resistance, obesity, systematic inflammation, metabolic endotoxemia, and gut permeability in mice could be reduced by LJP61A. Gut microbiota analysis showed that the gut microbiota dysbiosis of HFD-fed mice, especially the reduction in mucin-degrading Akkermansia, could be reversed by LJP61A. Additionally, the reduction in mucin-producing goblet cells in HFD-fed mice could also be reversed by LJP61A. Taurochenodeoxycholic acid mouse Moreover, insulin resistance, obesity, systematic inflammation, metabolic endotoxemia, and gut microbiota dysbiosis in HFD-fed mice could also be alleviated by faecal transplant from LJP61A-treated mice. Overall, LJP61A might be used as a prebiotic to ameliorate HFD-induced insulin resistance and associated metabolic disorders via regulating gut microbiota, especially Akkermansia.Mycotoxins cause significant harm to human health, so it is imperative to develop a highly sensitive and easy-to-operate method for the detection of mycotoxins. Herein, a fluorescence-based magnetic separation immunoassay for simultaneous detection of mycotoxins fumonisin B1 and zearalenone is established. The method employed high fluorescent upconversion-nanoparticles(UCNPs) conjugated with biotinylated antigens as upconversion fluoroscent probes. Magnetic nanoparticles(MNPs) immobilized with monoclonal antibodies are used as immune-capture probes. Highly sensitive detection of FB1 and ZEN was achieved based on the luminescence properties of UCNPs and the separation effects of MNPs. The results showed a robust linear correlation between the enhanced fluorescence emission intensity and the logarithmic concentrations of FB1 and ZEN under the optimal conditions (R2(FB1) = 0.9965, R2(ZEN) = 0.9976), and the linear ranges were 0.05-5 ng mL-1. Furthermore, the limits of detection (LOD) were 0.016 ng mL-1 for FB1 and 0.012 ng mL-1 for ZEN. The standard addition method was used to determine the content of FB1 and ZEN in the samples to evaluate the accuracy of the process. The average recoveries were 89.48% to 113.69% and 85.97% to 113.82%, respectively. Compared with the other five mycotoxins, this method had high selectivity. It is expected that the multi-component simultaneous detection can be further realized by using the multicolor labeling characteristics of UCNPs.The multivariate curve resolution-alternative least squares (MCR-ALS) algorithm was modified with sample insertion constraint to deconvolute the overlapping peaks in SERS spectra. The developed method was evaluated by the spectral data simulated using a Gaussian distribution function to generate two independent peaks corresponding to a capping agent and an analyte. The spectra were generated with different overlapping levels and various intensity ratios of the analyte to the capping agent. By using MCR-ALS with the sample insertion constraint, the peak of the capping agent was completely excluded to obtain a calibration model of the analyte with R2 > 0.95 under all conditions. Furthermore, our developed method was later applied to a real SERS measurement to quantify carbofuran (analyte) using the azo-coupling reaction with p-ATP (capping agent) on silver nanoparticles as a SERS substrate. A calibration model of derivative carbofuran phenol was generated with R2 = 0.99 and LOD = 28.19 ppm. To assess the performance of the calibration model, the model was used to estimate the concentration of carbofuran in an external validation set.