Metal oxide nanozymes hold significant promise as alternatives to natural enzymes, but their widespread use is limited by low catalytic activity and poor substrate specificity. To address this, we developed oxygen-vacancy-rich two-dimensional CoO atomic layers via controlled low-temperature pyrolysis under reduced oxygen partial pressure, a synthesis strategy that ensures high vacancy concentration while maintaining an ultrathin morphology, as confirmed by X-ray photoelectron spectroscopy and electron paramagnetic resonance. The introduced oxygen vacancies markedly enhance the peroxidase-like performance of V_o-CoO, resulting in a lower Michaelis–Menten constant and a higher catalytic turnover relative to pristine CoO. Density functional theory calculations further indicate that the vacancies reduce the adsorption energy of H₂O₂ and promote the desorption of H₂O molecules, elucidating the origin of the activity boost. Capitalizing on these properties, we constructed a highly sensitive and selective colorimetric sensor for ascorbic acid detection. The platform was successfully applied to quantify the total antioxidant capacity in complex real-world samples, demonstrating robust analytical utility. This work underscores defect engineering as a powerful approach for tailoring nanozyme activity and expands the scope of metal-oxide-based nanozymes in advanced sensing applications.

During the development of diet-induced obesity, the change of energy matebolism is closely related to the function of the circadian clock in mammals. Luteolin (LU), one of the most common natural flavonoids riched in many edible plants, can ameliorate obesity by activating adipose tissue browning, but its effect on circadian clock in this process remains poorly understood. Here we found that dietary LU improved circadian misalignment of energy expenditure in high-fat diet (HFD)-fed wild-type (WT) mice. Moreover, dietary LU efficiently elevated uncoupling protein 1 levels in adipose tissue during the dark period, which was similar to the LU-increased hepatic PER2 expressions. Hepatic peroxisome proliferators-activated receptors α (PPARα)/recombinant retinoid X receptor α (RXRα)/fibroblast growth factor 21 (FGF21) pathway was rhythmically elevated by dietary LU in HFD-fed WT mice, whereas the promotion was inhibited in Per2^-/- mice. Meanwhile, Per2 deletion abolished the effects of dietary LU on adipose tissue browning in HFD-fed mice. Further, LU treatment directly activated PPARα/RXRα/FGF21 signaling in primary cultured hepatocytes from WT mice rather than Per2^-/- mice. Taken together, the deletion of the core clock component Per2 impedes LU-induced adipose tissue browning through weakening PPARα/RXRα/FGF21 pathway in mice, providing a new insight into the interplay of energy metabolism and circadian clock for the anti-obesity activity of LU.

Food safety is a major issue to public health and have attracted global attention. Fast, sensitive, and reliable detection methods for food hazardous substances is highly desirable. Aptamers which can bind to the target molecules with high affinity and specificity represent an attractive tool for the recognition of food hazardous substances, which play an important role in the development and application of new food safety detection technology. But current assays for characterizing small molecule-aptamer binding are limited by either the mass sensitivity or the size differentiation ability. Herein, we proposed a comprehensive method for assessing the dissociation equilibria of small molecule-aptamer, which is immobilized-free under ambient conditions. The design employs the Le Chatelier's principle and could be used to effectively measure small molecule-aptamer interactions. ATP binding aptamer and anti-aflatoxin B1 aptamer were used as the model system to determine their affinity, in which their dissociation equilibria measurements are in excellent close to their previous work. Due to the simplicity and sensitivity of this new method, we believe that it could be recommended as an effective tool for characterizing small molecule-aptamer interactions and promote the further application of small molecular aptamer in food safety.