A point-of-care aptasensor based on the upconversion nanoparticles/MoS2 FRET system for the detection of Pseudomonas aeruginosa infection.

The rapid detection of Pseudomonas aeruginosa (P. aeruginosa) is of great significance for the diagnosis of medical infection. In view of the above, a novel aptasensor based on fluorescence resonance energy transfer (FRET) was developed. It contained aptamer-coupled upconversion nanoparticles (UCNPs-apt) as a donor (excitation 980 nm) and molybdenum disulfide (MoS2) nanosheets as an acceptor. The upconversion fluorescence aptamer system was investigated to obtain the optimal parameters of MoS2 concentration, the incubation time of UCNPs-apt/MoS2 and P. aeruginosa, and pH. Based on the optimal parameters, a linear calibration equation (emission 654 nm) with a wide detection range 8.7 × 10 ~ 8.7 × 107 cfu/mL, a high coefficient of determination R2 0.9941, and a low limit of determination (LOD) 15.5 cfu/mL were established. The method was validated with P. aeruginosa infected foci of mouse wound. The advantage of this aptasensor is that analysis results can be obtained  within 1.5 h, which was much faster than that of the standard method (18-24 h). Furthermore, combined with a portable instrument, it can be used as a point-of-care testing for the early detection of P. aeruginosa infection, which is useful for selecting the correct antibiotics to achieve good therapeutic effects. Additionally, it also has a broad application prospect in food and environmental areas.

Exogenous GABA improves the antioxidant and anti-aging ability of silkworm (Bombyx mori).

Silkworm (Bombyx mori) was used to explore the anti-aging ability of Gamma-aminobutyric acid (GABA) and its potential mechanism. 0.086∼8.6 mM GABA solutions were sprayed on mulberry leaves to raise silkworms. The results showed that GABA increased the fecundity of adult silkworms. And in the larva silkworms on the 3th day of the 5th instar, GABA significantly reduced the trehalose content in the hemolymph, the triglycerides and glycogen levels in the fat body, while sharply increased the NAD+/NADH level in the fat body. GABA significantly increased the GSH content and activities of SOD and CAT, while reduced the level of MDA. Furthermore, GABA reduced the mRNA expression of BmRpd3, Bmchico and BmAkh2, while increased the mRNA expression of BmAMPK. In summary, GABA has anti-aging potential by playing roles in energy homeostasis, reducing carbohydrate and lipid level, increasing anti-oxidative capacity, and regulating mRNA expression of longevity-related genes.

A stepwise control strategy for glutathione synthesis in Saccharomyces cerevisiae based on oxidative stress and energy metabolism.

A stepwise control strategy for enhancing glutathione (GSH) synthesis in yeast based on oxidative stress and energy metabolism was investigated. First, molasses and corn steep liquor were selected and fed as carbon source mixture at a flow rate of 1.5 g/L/h and 0.4 g/L/h, respectively, for increasing cell density in a 10 L fermenter. When the biomass reached 90 g/L, the KMnO4 sustained-release particles, composed of 1.5% KMnO4, 3% stearic acid, 2% polyethylene glycol and 3% agar powder, were prepared and added to the fermentation broth for maintaining the oxidative stress. The results showed that the maximum GSH accumulation of the group fed KMnO4 sustained-release particles was 39.0% higher than that of KMnO4-fed group. In addition to the improved average GSH productivity and average specific production rate, the activities of GSH peroxidase, γ-glutamylcysteine synthetase and GSH reductase, enzymes taking part in GSH metabolism, were also significantly enhanced by KMnO4 sustained-release particles feeding. Finally, 6 g/L sodium citrate fed as an energy adjuvant elevated the intracellular ATP level for further enhancing GSH production. Through the above stepwise strategy, the GSH accumulation reached 5.76 g/L, which was 2.84-fold higher than that of the control group. The stepwise control strategy based on oxidative stress and energy metabolism significantly improved GSH accumulation in yeast.

Solid state fermentation by Fomitopsis pinicola improves physicochemical and functional properties of wheat bran and the bran-containing products.

Wheat bran was solid state fermented by Fomitopsis pinicola. The results showed that the processing properties were increased by fermentation and the content of total phenol and alkylresorcinols was 5.91 and 1.55 times of the unfermented bran respectively by the 6th day. The total antioxidant capacity was 5.73 times of the unfermented sample by the 4th day. Electronic nose analysis showed that the fermented wheat bran had a special flavor. GC-MS analysis found that 4-ethyl-2-methoxy-phenol was the main flavor substance, which was sharply increased during the fermentation. Furthermore, the textural properties of the dough and bread containing fermented bran were significantly improved. The content of phytic acid in the bread was significantly decreased, while the protein, total phenol and alkylresorcinols contents were significantly increased. Results suggest that solid state fermentation by Fomitopsis pinicola is a promising way to improve wheat bran to a nutritious and flavorful cereal food ingredient.

Hypoglycemic effects of wheat bran alkyresorcinols in high-fat/high-sucrose diet and low-dose streptozotocin-induced type 2 diabetic male mice and protection of pancreatic ß cells.

In the present study, the hypoglycemic effects of wheat bran alkyresorcinols (ARs) were investigated in type 2 diabetes mellitus (T2DM) mice induced by a high-fat/high-sucrose diet (HFSD) combined with low dose streptozotocin (STZ). After the consumption of 5 mg kg-1 d-1 acarbose (positive control) and different doses of wheat bran ARs (50, 200 and 500 mg kg-1 d-1) for 4 weeks, the fasting blood glucose (FBG) levels in T2DM mice were found to be reduced significantly (p < 0.05), and the effects of 200 and 500 mg kg-1 d-1 administration were better than that of 50 mg kg-1 d-1. The results of the oral glucose tolerance test (OGTT) also showed that both acarbose and AR administration significantly increased the glucose tolerance of the T2DM mice. Then, the fasting serum insulin levels (FINS) were significantly reduced by AR treatment, and the effect of 500 mg kg-1 d-1 AR administration was better than that of 5 mg kg-1 d-1 acarbose. The profile of plasma lipids was analyzed simultaneously, and the results showed that the contents of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) were significantly decreased, while the content of high-density lipoprotein cholesterol (HDL-C) was increased significantly after 200 and 500 mg kg-1 d-1 AR treatment (p < 0.05). Furthermore, 200 and 500 mg kg-1 d-1 ARs significantly increased the content of hepatic glycogen and the activity of glucokinase (p < 0.01) in T2DM mice. The relative mRNA levels of glucose transporter 2 (GLUT2) in the liver tissue were increased markedly in 200 and 500 mg kg-1 d-1 AR treatment groups (p < 0.01), and the relative mRNA levels of glucose transporter 4 (GLUT4) in the epididymal adipose tissue were increased significantly in all AR treatment groups, especially significantly higher than acarbose (p < 0.01). Histological analyses revealed that treatment with ARs exerted a protective role on pancreatic ß-cells. The results indicated that ARs could be an effective hypoglycemic active ingredient in whole grain diets.