China
Africa
Explore chapters and articles related to this topic
Single-Molecule Biosensing by Fluorescence Resonance Energy Transfer
Published in Shuo Huang, Single-Molecule Tools for Bioanalysis, 2022
Step 1: Solution PreparationBuffer preparation: 20 mM Tris-HCl buffers (pH = 7.5 at 25oC) with different concentrations of NaCl (15 mM and 50 mM) are used. The buffers are autoclaved and membrane filtered. The prepared buffers can be stored at –20oC for long terms.Oxygen-scavenging system: The components of photo protection system are stored separately and mixed prior to each use. The solution of 50× ß-D-glucose is prepared by dissolving ß-D-glucose in ddH2O with a 1:2.5 (w/v) ratio. 100× glucose oxidase (165 U/mL, –20oC) is obtained by mixing it with T50 buffer (20 mM Tris-HCl and 50 mM NaCl) in 1:10 (w/v). 100× catalase (2170 U/mL, –20oC) is obtained by mixing it with T50 buffer in 1:25 (w/v) ratio. The glucose oxidase and catalase solution can be stored for 1 or 2 weeks. 4× Trolox can be obtained by mixing Trolox with T50 buffer (pH 7.5) in 1:1,000 (w/v). The Trolox buffer can be kept at –20oC (keep in dark place) for long-term storage.Streptavidin solution: Streptavidin (0.01 mg/mL in T50 buffer) is used to immobilize the biomolecules to the chamber surface.DNA solution: To form G quadruplexes, DNA oligonucleotides (Materials) were dissolved in the annealing buffer (25 mM Tris-HCl, 100 mM NaCl, 1 mM EDTA), incubated at 95°C for 5 minutes, and then gradually cooled down to 25oC in 7 hours. The solution is then stored at –20oC prior to use.
Nickel(II)-PPh3 complexes of substituted benzophenone thiosemicarbazones: Electrochemistry, structural analysis, and antioxidant properties
Published in Journal of Coordination Chemistry, 2020
The compounds were tested by the normal CUPRAC methods at ambient conditions [11, 22]. Trolox (TR) was utilized as the standard reference compound for all antioxidant capacity studies. The slope of the linear calibration curve was evaluated to calculate the molar absorption coefficient (ɛ). In order to estimate the TEAC coefficients, the ratio between each of εcompound and εTR was used in Table 4. The TEACCUPRAC of the ligands and complexes were calculated as 3.16, 1.42, 2.00, and 4.82 for L1H2, L2H2, L3H2, and L4H2, respectively. Amongst all the compounds, it was revealed that the highest TEACCUPRAC coefficient was 4.82 for L4H2. The reason for this behavior is attributed to the ligand (L4H2) containing two different hydroxyl groups located on the phenolic structure. The highest antioxidant potential of L4H2 is linked to its electron donation ability based on the electron-transfer mechanism. The TEACCUPRAC values for nickel(II) complexes (1–4) were 0.93, 0.54, 1.61, and 2.95, respectively. These complexes exhibit less antioxidant capacity compared to their own ligands, indicating the coordination of metal ion to the hydroxyl group located at the meta-position of phenolic ring.
Serum cortisol but not oxidative stress biomarkers are related to frailty: results of a cross-sectional study in Spanish older adults
Published in Journal of Toxicology and Environmental Health, Part A, 2019
Diego Marcos-Pérez, María Sánchez-Flores, Ana Maseda, Laura Lorenzo-López, José C. Millán-Calenti, Eduardo Pásaro, Blanca Laffon, Vanessa Valdiglesias
Total antioxidant capacity was measured in plasma samples by using the Antioxidant assay kit (Sigma Aldrich), following manufacturer´s guidelines. The principle of the assay is the formation of a radical cation, a soluble chromogen that is green in color and determined spectrophotometrically. Antioxidants present in the plasma samples suppress the production of the radical cation in a concentration-dependent manner, and the color intensity decreases proportionately. TroloxTM, a water-soluble vitamin E analog, serves as a standard or control antioxidant. Absorbance at 405 nm was measured with a Spectrostar Nano microplate reader (BMG Labtech) equipped with kinetic analysis software (Spectrostar Nano Control, BMG Labtech). Results were expressed as TroloxTM equivalent antioxidant capacity (TEAC). The sensitivity of this method was 0.015 mM TEAC.
Effect of precursor feeding, dietary supplementation, chemical elicitors and co-culturing on resveratrol production by Arcopilus aureus
Published in Preparative Biochemistry & Biotechnology, 2022
The assay mixture comprises of 10 µl of extract was added to 0.99 ml of diluted ABTS• solution and incubated for 6 min. The decrease in the O.D. was recorded at 734 nm spectrophotometer. Phosphate buffer saline was used as a blank, and working ABTS• solution was taken as control. Trolox was used as a standard anti-oxidant in the concentration range of 50–300 µg/ml and the radical scavenging was expressed as μg of Trolox equivalent/mg of sample.