Sensitive Electrochemical Sensor Based On an Aminated MIL-101(Cr) MOF for the Detection of Tartrazine

Synthesis of Bio-Base Fluorescence Carbon Dots for Selective Detection of Tartrazine and Sunset Yellow in Food Samples

A green, economical and simple method for the preparation of water-soluble, high-fluorescent carbon quantum dots (CQDs) has been developed via hydrothermal process using pomelo peels as carbon source. The synthesized CQDs were characterized by transmission electron microscopy (TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), UV - vis absorption spectra and fluorescence spectrophotometer. The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 2.64 nm and emit bright blue photoluminescence (PL) with a quantum yield of approximately 3.63%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including excellent photostability, low toxicity, and satisfactory solubility. Additionally, we found that two widely used synthetic food colorants, tartrazine and sunset yellow, could result in a strong fluorescence quenching of the C-dots, The possible mechanisms are caused by different ratios of inner filter and static quenching effects. According to this property, This study attempts to establish an analytical method for the determination of tartrazine and sunset yellow using carbon quantum dots as fluorescent probe. A linear relationship was found in the range of 0-100 µM tartrazine and sunset yellow with the detection limit(3σ/k) of 0.65 nM and 1.7 nM. The relative standard deviation (RSD) was 3.5% (tartrazine) and 3.0% (sunset yellow).This observation was further successfully applied for the determination of tartrazine and sunset yellow in food samples collected from local markets, and the recovery rates of the two ranges from 79% to 117.8 and 81 -103.5%, respectively. suggesting its great potential toward food routine analysis.

Multifunctional food packaging materials: Lactoferrin loaded Cr-MOF in films-based gelatin/κ-carrageenan for food packaging applications

In this study, antimicrobial biocomposite films based on gelatin-κ-carrageenan (Gκ) with 1, 2 and 4 % lactoferrin (L) loaded chromium-based metal-organic frameworks (L@Cr-MOFs) nanoparticles were synthesized by casting methods. The addition of L loaded Cr-MOFs into Gκ based films increased elongation at break from 2.19 to 14.92 % and decreased the tensile strength from 65.1 to 31.22 MPa. L@Cr-MOFs addition reduced swelling index (from 105 to 70.8 %), water solubility (from 61.3 to 34.63 %) and water vapor permeability (from 2.46 to 2.19 × 10-11 g. m/m2. s). When the additional amount was 4 wt%, the Gκ/L@Cr-MOFs films showed antibacterial effects against Escherichia coli and Staphylococcus aureus with the inhibition zone of 19.7 mm and 20.2 mm, respectively. In addition, strawberries preservation trial shown that the Gκ/L@Cr-MOFs films delayed the growth of spoilage molds on the surface of fruits. This research indicated that Gκ/L@Cr-MOFs are promising active packaging materials for the preservation of perishable fruits.

Sensitive and rapid detection of influenza A virus for disease surveillance using dual-probe electrochemical biosensor

Influenza A virus (IAV) can cause influenza, a highly infectious zoonotic respiratory disease, and early detection is essential to prevent and control its rapid spread in the population. Given the limitations of traditional detection methods in clinical laboratories, we report a large surface TPB-DVA COFs (TPB: 1,3,5-Tris(4-aminophenyl) benzene, DVA: 1,4-Benzenedicarboxaldehyd, COFs: Covalent organic frameworks) nanomaterial modified electrochemical DNA biosensor, which has dual-probe specific recognition and signal amplification. The biosensor enables quantitative detection of influenza A viruses' complementary DNA (cDNA) from 10 fM to 1 × 10³ nM (LOD = 5.42 fM) with good specificity and high selectivity. The reliability of the biosensor and portable device was verified by comparing the virus concentrations in animal tissues with those measured by digital droplet PCR (ddPCR) (P > 0.05). Moreover, the potential for influenza surveillance in this work was demonstrated by detecting the tissue samples from mice at different stages of infection. In summary, the good performance of this electrochemical DNA biosensor we proposed suggested it has the potential to be a rapid detection device for the influenza A virus, which could assist doctors or other professionals in obtaining rapid and accurate results for outbreak investigation and disease diagnosis.

Cr-MOF-Based Electrochemical Sensor for the Detection of P-Nitrophenol

Cr-MOF nanoparticles were synthesized by a simple hydrothermal method, and their morphology and structure were characterized by SEM, TEM, and XRD techniques. The Cr-MOF modified glassy carbon electrode (Cr-MOF/GCE) was well constructed and served as an efficient electrochemical sensor for the detection of p-nitrophenol (p-NP). It was found that the Cr-MOF nanoparticles had significant electrocatalytic activity toward the reduction of p-NP. The Cr-MOF-based electrochemical sensor exhibited a low detection limit of 0.7 μM for p-NP in a wide range of 2~500 μM and could maintain excellent detection stability in a series of interfering media. The electrochemical sensor was also practically applied to detect p-NP in a local river and confirmed its validity, showing potential application prospects.

Advances in Metal-Organic Frameworks MIL-101(Cr)

MIL-101(Cr) is one of the most well-studied chromium-based metal-organic frameworks, which consists of metal chromium ion and terephthalic acid ligand. It has an ultra-high specific surface area, large pore size, good thermal/chemical/water stability, and contains unsaturated Lewis acid sites in its structure. Due to the physicochemical properties and structural characteristics, MIL-101(Cr) has a wide range of applications in aqueous phase adsorption, gas storage and separation, and catalysis. In this review, the latest synthesis of MIL-101(Cr) and its research progress in adsorption and catalysis are reviewed.