ABSTRACT
Sesamol (SM) is a potent natural antioxidant that can quench free radicals and modulate the cholinergic system in the brain, thereby ameliorating memory and cognitive impairment in Alzheimer's disease patients. Moreover, the total antioxidant capacity can be amplified by synergistic interactions between different antioxidants. Here, we constructed a ternary heterojunction graphitic carbon nitride/cupric sulfide/titanium dioxide (g-C3N4/CuS/TiO2) photoelectrochemical (PEC) sensor for the quantification of SM and its synergistic interactions with other antioxidants. Crucially, the Schottky barrier in ternary semiconductors considerably enhances electron transfer. The PEC sensor showed a wide linear range for SM detection, ranging from 2 to 1277 µmol L-1, and had a limit of detection of 1.8 µmol L-1. Remarkably, this sensing platform could evaluate the synergism between SM and five typical lipid-soluble antioxidants: tert-butyl hydroquinone, vitamin E, butyl hydroxyanisole, propyl gallate, and butylated hydroxytoluene. Owing to its low redox potential, SM could reduce antioxidant radicals and promote their regeneration, which increased the overall antioxidant performance. The g-C3N4/CuS/TiO2 PEC sensor exhibited high sensitivity, satisfactory selectivity, and stability, and was successfully applied for SM determination in both soybean and peanut oils. The findings of this study provide guidance for the development of nutritional foods, nutrition analysis, and the treatment of diseases caused by free radicals.
Subject(s)
AntioxidantsABSTRACT
A near-infrared (NIR) light-driven NaYF4:Yb/Er-TiO2-Ti3C2 (NYF-TiO2-Ti3C2) heterostructure-based photoelectrochemical (PEC) biosensing platform was constructed for highly sensitive d-serine (d-ser) detection. Accurate d-ser detection depends on the model biocatalyst, d-amino acid oxidase (DAAO), which converts d-ser into hydroxypyruvate and an equimolar concentration of hydrogen peroxide (H2O2) via an enzymatic reaction. The TiO2-Ti3C2 semiconductor and NaYF4:Yb/Er optical transducer formed a Schottky junction that provided an irreversible channel for electron transfer. Infrared light was converted into absorbable multiemission light, thereby effectively increasing light absorption. Simultaneously, the generated H2O2 rapidly scavenged photogenerated holes to separate electron-hole pairs, which amplified the photocurrent signal. Under optimal conditions, the NIR light-driven PEC biosensor exhibited an excellent PEC performance for d-ser detection, with a wide linear range of 2-1650 µmol L-1 and detection limit as low as 0.286 µmol L-1. Importantly, high detection reproducibility and accuracy were achieved using this strategy for analyzing human serum and rat cerebrospinal fluid (CSF) specimens. The admirable applicability of the NYF-TiO2-Ti3C2-based PEC biosensor for detecting d-ser may lead to further opportunities for detecting other disease-related biomarkers.
Subject(s)
Biosensing Techniques , Electrochemical Techniques , Humans , Rats , Animals , Titanium/chemistry , Hydrogen Peroxide , Serine , Reproducibility of Results , Limit of DetectionABSTRACT
OBJECTIVE: To study the association of methylenetetrahydrofolate reductase (MTHFR) gene C677T mutation and plasma homocysteine (Hcy) levels with hyperlipidemia. METHODS: Blood samples were collected from 1591 adults for detecting MTHFR gene C677T polymorphism with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), plasma Hcy levels with enzymatic cycling method, and blood lipid levels as well. The patients were divided according to the lipid levels into hyperlipidemia group (n=694) and healthy control group (n=897) and the differences in MTHFR gene C677T polymorphisms and plasma Hcy levels were compared. RESULTS: The hyperlipidemia group and healthy control group showed no significant differences in CC, CT, or TT genotype frequencies or C and T allele frequencies of MTHFR C677T gene, and had comparable plasma Hcy levels (P>0.05). Patients with 3 different MTHFR C677T genotypes had significant differences in plasma Hcy levels (P<0.01) but not in blood lipid levels (P>0.05). Pairwise comparison indicated a significantly higher plasma Hcy level in TT genotype than in CC and CT genotypes (P<0.01), and the latter two genotypes showed no significant difference (P>0.05). CONCLUSION: MTHFR C677T polymorphisms and plasma Hcy levels are closely related but neither of them is associated with hyperlipidemia. The TT genotype is associated with a significantly higher plasma Hcy level than CC and CT genotypes.