A Novel Staphylococcal Enterotoxin Q Immunosensor Prepared with Self-Assembly Method Based on Horseradish Peroxidase and Double-Layer Gold Nanoparticles

Study of the Sensing Kinetics of G Protein-Coupled Estrogen Receptor Sensors for Common Estrogens and Estrogen Analogs

Endogenous and exogenous estrogens are widely present in food and food packaging, and high levels of natural estrogens and the misuse or illegal use of synthetic estrogens can lead to endocrine disorders and even cancer in humans. Therefore, it is consequently important to accurately evaluate the presence of food-functional ingredients or toxins with estrogen-like effects. In this study, an electrochemical sensor based on G protein-coupled estrogen receptors (GPERs) was fabricated by self-assembly, modified by double-layered gold nanoparticles, and used to measure the sensing kinetics for five GPER ligands. The interconnected allosteric constants (K_a) of the sensor for 17β-estradiol, resveratrol, G-1, G-15, and bisphenol A were 8.90 × 10^-17, 8.35 × 10^-16, 8.00 × 10^-15, 5.01 × 10^-15, and 6.65 × 10^-16 mol/L, respectively. The sensitivity of the sensor for the five ligands followed the order of 17β-estradiol > bisphenol A > resveratrol > G-15 > G-1. The receptor sensor also demonstrated higher sensor sensitivity for natural estrogens than exogenous estrogens. The results of molecular simulation docking showed that the residues Arg, Glu, His, and Asn of GPER mainly formed hydrogen bonds with -OH, C-O-C, or -NH-. In this study, simulating the intracellular receptor signaling cascade with an electrochemical signal amplification system enabled us to directly measure GPER-ligand interactions and explore the kinetics after the self-assembly of GPERs on a biosensor. This study also provides a novel platform for the accurate functional evaluation of food-functional components and toxins.

Study on the distribution of umami receptors on the tongue and its signal coding logic based on taste bud biosensor

Taste signals are uniformly encoded and transmitted to the brain's taste center by taste buds, and the process has not been systematically studied for several decades. The aim of this work was to investigate the distribution of umami receptors on the tongue and its signal coding logic based on the taste bud biosensors. Taste bud biosensors were constructed by immobilizing the taste bud tissues from different tongue regions of the rabbit to the glassy carbon electrode surface; The Shennong information equations were used to analysis the pattern of umami receptors to encode ligands information; The signal amplification capabilities of two types umami receptors (T1R1/T1R3 and mGluRs) were analyzed for the two ligands (L-monosodium glutamate (MSG) and disodium 5'-inosinate (IMP)). The results showed that each taste bud biosensor could sense MSG and IMP with different response currents based on enzyme-substrate kinetics. There was only a small fraction of a great quantity of metabotropic glutamate receptors (mGluRs) could be activated to encode MSG signal. Importantly, T1R1 was more expressed in the rostral tongue cells whose sensitivity to MSG was nearly 100 times stronger than that of caudal tongue cells. The method we proposed made it possible to reveal the distribution and signals coding logic of umami receptors for ligands, which showed great potential to explain the interaction mechanism of umami substances with their receptors more accurately and to develop of artificial intelligent taste sensory.

Construction of a Ginseng Root-Meristem Sensor and a Sensing Kinetics Study on the Main Nitrogen Nutrients

Severe continuous cropping obstacles exist in ginseng cultivation. In order to assess these obstacles, a "sandwich" ginseng root tissue sensor was developed for the kinetic determination of five nitrogen nutrients. The results showed that the sensing parameters of the sensor reached an ultrasensitive level (limit of detection up to 5.451 × 10-24 mol/L) for the five nitrogen nutrients, and exhibited good stability and reproducibility. In the order of two-, four-, and six-year-old ginseng plants, the sensitivity to inorganic nitrogen nutrients (sodium nitrate and urea) showed an upward trend following an initial decline (the interconnected allosteric constant Ka values acted as the parameter). The fluctuations in sensor sensitivity to organic nitrogen nutrients, specifically nucleotides (disodium inosinate and disodium guanylate), were relatively small. The sensor sensitivity of two-, four-, and six-year-old ginseng plants to sodium glutamate was 9.277 × 10-19 mol/L, 6.980 × 10-21 mol/L, and 5.451 × 10-24 mol/L, respectively. Based on the survival rate of the seedlings and mortality rate of the ginseng in each age group, a Hardy-Weinberg equilibrium analysis was carried out. The results showed that the sensing ability of the root system to sodium glutamate may be an important factor affecting its survival under continuous cropping obstacles with increasing age.

Preliminary research on the receptor–ligand recognition mechanism of umami by an hT1R1 biosensor

The biosensor reflecting the linkage of the umami signal during conduction and amplification, and the study on the receptor–ligand recognition mechanism.