Boric acid functionalized Fe3O4@CeO2/Tb-MOF as a luminescent nanozyme for fluorescence detection and degradation of caffeic acid

Caffeic acid (CA) is a natural polyphenol that can have various positive effects on human health. However, its extraction and processing can cause significant ecological issues. Therefore, it is crucial to detect and degrade CA effectively in the environment. In this study, we have developed a multifunctional magnetic luminescent nanozyme, Fe3O4@CeO2/Tb-MOF, which combines peroxidase activity to detect and degrade CA. The fluorescence of the nanozyme was significantly attenuated due to the specific nucleophilic reaction between its boronic acid moiety and the o-diphenol hydroxyl group of CA, energy competition absorption and photo-induced electron transfer (PET) effect. This nanozyme demonstrates a linear detection range from 50 nM to 500 μM and an exceptionally low detection limit of 18.9 nM, along with remarkable selectivity and stability. Moreover, the synergistic catalysis of Fe3O4 and CeO2 within Fe3O4@CeO2/Tb-MOF fosters peroxidase activity, leading to the generation of substantial free radicals catalyzed by H2O2, which ensures the efficient degradation of CA (∼95%). The superparamagnetic property of Fe3O4 further enables the efficient reuse and recycling of the nanozyme. This research provides a novel approach for the concurrent detection and remediation of environmental contaminants.

Self-powered molecularly imprinted photoelectrochemical sensor based on Ppy/QD/HOF heterojunction for the detection of bisphenol A

As an emerging porous material, hydrogen-bonded organic framework materials (HOFs) still pose application challenges. In this work, the designed type "I + II" heterojunction extracted hot electrons from HOFs using quantum dots (QDs) and polypyrrole (Ppy), improving the stability and photoelectrochemical performance of materials. In addition to serving as a potential well, electropolymerized Ppy was used as a recognition element for bisphenol A (BPA), and a novel self-powered molecularly imprinted photoelectrochemical (MIP-PEC) sensor was designed. The sensing platform showed a linear relationship from 1 × 10-10 to 1 × 10-7 mol∙L-1 and from 1 × 10-7 to 1 mol∙L-1 with an acceptable detection limit of 4.2 × 10-11 mol∙L-1. This is the first application of HOFs in constructing MIP-PEC sensors and a new attempt to improve the stability of HOFs for the application of porous crystal materials in the sensing field.

Two birds with one stone: A universal design and application of signal-on labeled fluorescent/electrochemical dual-signal mode biosensor for the detection of tetracycline residues in tap water, milk and chicken

An ingenious and universal design of fluorescent/electrochemical dual-signal mode sensing platform was constructed for the sensitive, selective and accurate detection of tetracycline (TET). Apt-functionalized nano-magnetic beads (Fe3O4-Apt) as capture probe, Apt-complementary short-chain functionalized fluorescent MOF loaded with methylene blue (MB) (cDNA-MOF-MB) as dual-signal tag were prepared. The sensing platform (Fe3O4-Apt/cDNA-MOF-MB) was formed based on the base complementary pairing of Apt and cDNA. With the help of Apt for target recognition, together with magnetic separation technology, a dual-signal mode biosensor was constructed. The dual-signal mode biosensor exhibited a wide linear concentration range from 1.00 × 10-9 g/mL to 1.00 × 10-4 g/mL with a low limit of detection (LOD) of 1.69 × 10-10 g/mL (fluorescence mode assay) and 1.15 × 10-10 g/mL (electrochemical mode assay). The proposed biosensor had been successfully applied to the determination of TET content in real samples with satisfactory recoveries (94.99-101.30%).

Antifungal molecular details of MNQ-derived novel carbon dots against Penicillium digitatum

It is urgent to develop high-efficiency and low-toxicity natural antifungal agents on green mold caused by Penicillium digitatum. The effect of 2-methoxy-1, 4-naphthoquinone (MNQ) inhibition of P. digitatum was not very satisfactory. MNQ-derived carbon dots (MNQ-CDs) synthesized through a solvothermal route were used as antifungal agents against P. digitatum. The antifungal activity of prepared MNQ-CDswas enhanced compared to MNQ, and the minimum inhibitory concentration was 2.8 μg/mL. A total of 441 genes and 122 metabolites have undergone significant changes. The omics data revealed that MNQ-CDs primarily modified the metabolism of aromatic amino acids and synthesis of the cell membrane in P. digitatum, thereby inhibiting its propagation. Furthermore, compared with MNQ, MNQ-CDs had a better control effect on the green mold of citrus fruits, and could more significantly inhibit the propagation of P. digitatum. This study provides a new idea for the design of new and efficient antifungal materials.

Beer-derived nitrogen, phosphorus co-doped carbon quantum dots: Highly selective on-off-on fluorescent probes for the detection of ascorbic acid in fruits

A rapid, facile and ultrasensitive fluorescence sensing system based on beer-derived nitrogen, phosphorus co-doped carbon quantum dots (N, P-CQDs) for the detection of ascorbic acid (AA) in fruits was proposed. N, P-CQDs were successfully synthesized by one-step hydrothermal method, which afforded a high quantum yield (21.7 %), and showed the fluorescence with a maximum emission wavelength of 450 nm at an excitation wavelength of 370 nm. Further, N, P-CQDs were employed as an efficient sensor for ultrasensitive Fe³⁺-detection at concentrations ranging from 1-20 µM and 100-300 µM, respectively. N, P-CQDs@Fe³⁺ showed a high sensitivity and selectivity for AA detection. A linear response range for AA was obtained from 1 to 200 µM with limit of detection of 0.84 µM was obtained for AA. The result of MTT test showed that N, P-CQDs exhibit low toxicity, providing fast, accurate and less toxic route for testing AA in the food analysis fields.

Modulation of integrin receptor by polyphenols: Downstream Nrf2-Keap1/ARE and associated cross-talk mediators in cardiovascular diseases

As a group of heterodimeric and transmembrane glycoproteins, integrin receptors are widely expressed in various cell types overall the body. During cardiovascular dysfunction, integrin receptors apply inhibitory effects on the antioxidative pathways, including nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch like ECH Associated Protein 1 (Keap1)/antioxidant response element (ARE) and interconnected mediators. As such, dysregulation in integrin signaling pathways influences several aspects of cardiovascular diseases (CVDs) such as heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. So, modulation of integrin pathway could trigger the downstream antioxidant pathways toward cardioprotection. Regarding the involvement of multiple aforementioned mediators in the pathogenesis of CVDs, as well as the side effects of conventional drugs, seeking for novel alternative drugs is of great importance. Accordingly, the plant kingdom could pave the road in the treatment of CVDs. Of natural entities, polyphenols are multi-target and accessible phytochemicals with promising potency and low levels of toxicity. The present study aims at providing the cardioprotective roles of integrin receptors and downstream antioxidant pathways in heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. The potential role of polyphenols has been also revealed in targeting the aforementioned dysregulated signaling mediators in those CVDs.