Design of an effective small expression tag to enhance GPCR production in E. coli-based cell-free and whole cell expression systems.

G protein-coupled receptors (GPCRs) play crucial roles in sensory, immune, and tumor metastasis processes, making them valuable targets for pharmacological and sensing applications in various industries. However, most GPCRs have low production yields in Escherichia coli (E. coli) expression systems.

Advances in the Production of Olfactory Receptors for Industrial Use.

In biological olfactory systems, olfactory receptors (ORs) can recognize and discriminate between thousands of volatile organic compounds with very high sensitivity and specificity. The superior properties of ORs have led to the development of OR-based biosensors that have shown promising potential in many applications over the past two decades. In particular, newly designed technologies in gene synthesis, protein expression, solubilization, purification, and membrane mimetics for membrane proteins have greatly opened up the previously inaccessible industrial potential of ORs.

FET-based nanobiosensors for the detection of smell and taste.

Various nanobiosensors composed of biomaterials and nanomaterials have been developed, due to their demonstrated advantage of showing high performance. Among various biomaterials for biological recognition elements of the nanobiosensor, sensory receptors, such as olfactory and taste receptors, are promising biomaterials for developing nanobiosensors, because of their high selectivity to target molecules. Field-effect transistors (FET) with nanomaterials such as carbon nanotube (CNT), graphene, and conducting polymer nanotube (CPNT), can be combined with the biomaterials to enhance the sensitivity of nanobiosensors.

Co₃O₄/Au Hybrid Nanostructures as Efficient Peroxidase Mimics for Colorimetric Biosensing.

Nanomaterials with enzyme-like characteristics (nanozymes) have emerged as potential replacements for natural enzymes due to their potential to overcome several critical limitations of natural enzymes, including low stability as well as high costs in preparation and purification. Herein, we have developed hybrid nanostructures that incorporate cobalt oxide nanoparticles (Co₃O₄ NPs) and gold nanoclusters (AuNCs) through electrostatic attraction induced by simple incubation in an aqueous buffer for 2 hours. Owing to the synergistic effect of Co₃O₄ NPs and AuNCs, the constructed Co₃O₄/Au hybrid nanostructures yielded highly enhanced peroxidase-like activity and enabled rapid catalytic oxidation of a chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB), producing a blue colored solution depending on the amount of H₂O₂.

Visual detection of odorant geraniol enabled by integration of a human olfactory receptor into polydiacetylene/lipid nano-assembly.

A new polydiacetylene lipid/human olfactory receptor nano-assembly was fabricated for the visual detection of an odorant for the first time. The assembly consisted of phospholipid-mixed polydiacetylenes (PDAs) and human olfactory receptors (hORs) in detergent micelles. To overcome the limitations of bioelectronic noses, hOR-embedded chromatic complexes (PDA/hORs) were developed, introducing PDAs that showed color and fluorescence transitions against various stimuli.

N- and B-Codoped Graphene: A Strong Candidate To Replace Natural Peroxidase in Sensitive and Selective Bioassays.

The work describes a carbon-based peroxidase mimic, N- and B-codoped reduced graphene oxide (NB-rGO), which shows high peroxidase-like activity without oxidase-like activity and has a catalytic efficiency nearly 1000-fold higher than that of undoped rGO. The high catalytic activity of NB-rGO is explained by density functional theory by calculating Gibbs free energy change during the peroxide decomposition reaction. Acetylcholine and C-reactive protein are successfully quantified with high sensitivity and selectivity, which were comparable to or better than those obtained using natural peroxidase.

Highly Efficient Electrochemical Detection of Phenolic Compounds Utilizing Superior Catalytic Activity of Nanohybrids Consisting of Magnetic Nanoparticles and Gold Nanoclusters.

Although Fe3O4 magnetic nanoparticles (MNPs) have gathered particular interest as potent peroxidase mimetics, their practical utility has been critically limited by their low catalytic activity. Here, we have developed a nanohybrid material to significantly enhance the catalytic activity of MNPs by incorporating other enzyme mimetics, gold nanoclusters (AuNCs), through electrostatic attraction. Owing to the synergistic effect of MNPs and AuNCs, the constructed nanohybrid yielded highly enhanced peroxidase-like activity and higher resolution in electrochemical detection of H2O2 than bare MNPs.

Highly sensitive colorimetric detection of allergies based on an immunoassay using peroxidase-mimicking nanozymes.

Nanomaterials that exhibit enzyme-like characteristics, which are called nanozymes, have recently attracted significant attention due to their potential to overcome the intrinsic limitations of natural enzymes, such as low stability and relatively high cost for preparation and purification. In this study, we report a highly efficient colorimetric allergy detection system based on an immunoassay utilizing the peroxidase-mimicking activity of hierarchically structured platinum nanoparticles (H-Pt NPs). The H-Pt NPs had a diameter of 30 nm, and were synthesized by a seed-mediated growth method, which led to a significant amount of peroxidase-like activity.

Pt-Decorated Magnetic Nanozymes for Facile and Sensitive Point-of-Care Bioassay.

Development of facile and sensitive bioassays is important for many point-of-care applications. In this study, we fulfilled such demand by synthesizing Pt-decorated magnetic nanozymes and developing a bioassay based on unique properties of the newly synthesized nanozymes. FeO-Pt/core-shell nanoparticles (MPt/CS NPs) with various compositions were synthesized and characterized.

Nanohybrids consisting of magnetic nanoparticles and gold nanoclusters as effective peroxidase mimics and their application for colorimetric detection of glucose.

Although protein-stabilized gold nanoclusters (AuNCs) have gathered recent attention as biocompatible peroxidase mimics, their practical utility has been critically limited by the low catalytic activity. Here, the authors have developed a nanohybrid material to significantly enhance the catalytic activity of AuNCs by combining them with other inorganic enzyme mimetics, FeO magnetic nanoparticles (MNPs), through electrostatic attraction. Owing to the synergistic effect by incorporating AuNCs and MNPs, the constructed nanohybrids yielded highly enhanced catalytic activity and enabled rapid catalytic oxidation of 3,3',5,5'-tetramethylbenzidine substrate to produce a blue-colored solution in proportional to the amount of HO.

Nitric oxide induces apoptosis in mouse C2C12 myoblast cells.

To investigate whether nitric oxide (NO) induces apoptosis in myoblast cells, the effect of the sodium nitroprusside (SNP), NO donor, on the apoptosis of mouse C2C12 myoblast cells was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, 4,6-diamidino-2-phenylindole (DAPI) staining, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, DNA fragmentation assay, reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis, and caspase-3 enzyme assay. Mouse C2C12 myoblast cells treated with SNP exhibited several apoptotic features. SNP increased p53 expression and bax expression.

Hypothermia inhibits cell proliferation and nitric oxide synthase expression in rats.

In the present study, the effects of cold-water immersion on cell proliferation and nitric oxide synthase expression in the dentate gyrus of rats were investigated. Sprague-Dawley rats were divided into four groups: the control-rest group; the control-heat group; the cold-rest group; and the cold-heat group. Cold-water immersion for 5 min at 4 degrees C suppressed the numbers of 5-bromo-2'-deoxyuridine-positive and nicotinamide adenine dinucleotide phosphate-diaphorase-positive cells in the dentate gyrus, and these numbers were increased by warming for 30 min at 30 degrees C.