Latest ArticlesThe fabrication of bioreceptor-free method for accurate and sensitive detection of ochratoxin A (OTA) in cereal is critical, but still a significant challenge to mitigate risks to food industries and public health. In this study, a smartphone-ratiometric fluorescence sensor for the ultrasensitive detection of OTA is developed based on a porphyrinic metal-organic framework and silica nanoparticle composite (Zr-MOF/SiNPs) away from the use of antibodies and aptamers. Due to the excellent recognition ability of Zr-MOF and good storage stability of SiNPs, OTA is detected by Zr-MOF/SiNPs with a wide linear range of 0.05–1000 ng/mL and low detection limit of 0.016 ng/mL. Moreover, the red–blue ratio values of the fluorescence images are extracted through the smartphone color recognizer application with a limit of detection of 1.74 ng/mL, lower than the permissible content of OTA in cereal prescribed by World Health Organization. This sensing platform has been successfully applied in maize samples with superior repeatability and satisfactory recoveries, providing a novel way for simple and label-free analysis of OTA in cereal.
A novel Fe-doping three-dimensional flower-like Bi7O9I3 microspheres with plasmonic Bi and rich surface oxygen vacancies (Fe-Bi/Bi7O9I3/OVs) was prepared as catalysts, and further coupled with natural air diffusion electrode (NADE) to construct the heterogeneous visible-light-driven photoelectro-Fenton (HE-VL-PEF) process to enhance the degradation and mineralization of tetracycline (TC). Interfacial ≡Fe sites, OVs and Bi metal were simultaneously constructed via Fe doping, which effectively improved visible light absorption and the separation efficiency of photogenerated carriers to further accelerate the transformation of Fe(Ⅲ) to Fe(Ⅱ), achieving Fenton reaction recycling. HE-VL-PEF process could achieve enhanced treatment of pollutants, thanks to the synergistic effect of electro-Fenton (EF) and photo-Fenton (PF). NADE exhibited excellent H2O2 electrosynthesis without external oxygen-pumping equipment. Under the irradiation of visible light, Fe-Bi/Bi7O9I3/OVs could achieve more photoelectrons to accelerate the transformation of Fe(Ⅲ) to Fe(Ⅱ) or directly activate H2O2. DFT calculations also clearly demonstrated that except for the fast charge separation and transfer, Fe-Bi/Bi7O9I3/OVs could achieve a faster electron transport between Fe-O, facilitating Fe site acquire more electron. Consequently, the Fe-Bi/Bi7O9I3/OVs in HE-VL-PEF process presented performance superiorities including excellent pollutant removal (91.91%), low electric energy consumption of 66.34 kWh/kg total organic carbon (TOC), excellent reusability and wide pH adaptability (3–9).
Degrading volatile organic compounds at low temperatures and active sites aggregation are still challenging. In this study, a novel mesoporous zeolite silicalite-1 (S-1-meso) enveloped Pt–Ni bimetallic catalysts (noted as Pt1Ni1@S-1-meso) were synthesized via a facile in situ mesoporous template-free method. The Pt–Ni bimetallic nanoparticles were uniformly distributed and displayed a large specific surface area and enriched mesopores to facilitate the deep oxidation of toluene. The presence of the Pt–NiO interface both increased the dispersion of the catalyst and improved its catalytic performance, thereby reducing the consumption of Pt. The Mars-van Krevelen mechanism and density function theory (DFT) calculations revealed that the Pt–NiO interface effect changed the electronic structure of Pt and Ni species, reduced the activation potential for oxygen, formed reactive oxygen species, and facilitated the adsorption and activation of reactants in the direction favorable to the toluene oxidation. This study provides a guideline for minimizing the proportion of precious metals used in practical applications and a promising method for toluene elimination at low temperatures.
The widespread occurrence of antibiotics in wastewater aroused serious attention. UV-based advanced oxidation processes (UV-AOPs) are powerful technologies in removing antibiotics in wastewater, which include UV/catalyst, UV/H2O2, UV/Fenton, UV/persulfate, UV/chlorine, UV/ozone, and UV/peracetic acid. In this review, we collated recent advances in application of UV-AOPs for the abatement of fluoroquinolones (FQs) as widely used class of antibiotics. Representative FQs of ciprofloxacin, norfloxacin, ofloxacin, and enrofloxacin were most extensively studied in the state-of-art studies. The evolvement of gas-state and solid-state UV light sources was presented and batch and continuous flow UV reactors were compared towards practical applications in UV-AOPs. Generally, degradation of FQs followed the pseudo-first order kinetics in UV-AOPs and strongly affected by the operating factors and components of water matrix. Participation of reactive species and transformation mechanisms of FQs were compared among different UV-AOPs. Challenges and future prospects were pointed out for providing insights into the practical application of UV-AOPs for antibiotic remediation in wastewater.
Developing BiVO4 photoanode with efficient carrier transfer and fast water oxidation kinetics is the permanent pursuit to achieve the state-of-art solar-driven photoelectrochemical (PEC) water splitting. The capacity to increase the PEC activity of BiVO4 by loading oxygen evolution co-catalysts (OECs) has been proven, however it suffers from sluggish charge carriers dynamics brought on by the complicated interface between BiVO4 and OECs as well as poor long-term durability. Herein, we connected OECs (NiFeOx) and photoanode with a Al-O bridge for bettering the PEC performance of BiVO4. The Al-O bridge served as a channel to extract hole from BiVO4 to NiFeOx, thus boosting charge carriers′ separation and preventing BiVO4 from photo-corrosion. The Al-O bridging photoanode (NiFeOx/Al2O3/BiVO4) demonstrated a high photocurrent density of 5.87 mA/cm2 at 1.23 V vs. RHE and long-term photostability in comparison to NiFeOx/BiVO4 photoanode. This study proposes a unique technique to boost charge carriers′ separation between BiVO4 and OECs for high-efficiency solar-driven PEC water splitting.
Rapid diagnosis of Salmonella is crucial for the effective control of food safety incidents, especially in regions with poor hygiene conditions. Polymerase chain reaction (PCR), as a promising tool for Salmonella detection, is facing a lack of simple and fast sensing methods that are compatible with field applications in resource-limited areas. In this work, we developed a sensing approach to identify PCR-amplified Salmonella genomic DNA with the naked eye in a snapshot. Based on the ratiometric fluorescence signals from SYBR Green Ⅰ and Hydroxyl naphthol blue, positive samples stood out from negative ones with a distinct color pattern under UV exposure. The proposed sensing scheme enabled highly specific identification of Salmonella with a detection limit at the single-copy level. Also, as a supplement to the intuitive naked-eye visualization results, numerical analysis of the colored images was available with a smartphone app to extract RGB values from colored images. This work provides a simple, rapid, and user-friendly solution for PCR identification, which promises great potential in molecular diagnosis of Salmonella and other pathogens in field.
For nano-collision, regulating the interaction between nanoparticles (NPs) and electrode interfaces is crucial for the precise analysis of individual NPs. However, existing ultramicroelectrodes (UMEs) suffer from narrow electrochemical window and poor electrode interface adhesion, severely hindering the application of precise single NP analysis. Here, we propose a simple and effective interface modification strategy. By electrochemically self-assembling poly(diallyldimethylammonium chloride) (PC) on the surface of carbon nanocone electrodes (CNCEs), we successfully prepared PC-modified CNCEs (PC‑CNCEs). These electrodes not only possess sufficiently wide electrochemical window but also exhibit strong adhesion to negatively charged Ag NPs on their surfaces. Surface physical analysis and electrochemical molecule detection validated the high-density loading of PC on the modified electrodes. Furthermore, the working principle of PC‑CNCEs for single Ag NP collision detection was further verified through the techniques of nano-collision and double-potential steps. Leveraging these significant advantages, PC‑CNCEs not only achieved precise measurements of single or mixed-sized Ag NPs but also detected Ag NP solutions at concentrations as low as fmol/L levels. This advancement offers a new strategy for the rapid and precise analysis of NP colloids.
Compared with natural enzymes, nanozymes have the advantages of high stability and low cost; however, selectivity and sensitivity are key issues that prevent their further development. In this study, we report a cascade nanozymatic system with significantly improved selectivity and sensitivity that combines more substrate-specific reactions and sensitive fluorescence detection. Taking detection of ascorbic acid (AA) as an example, a cascade catalytic reaction system consisting of oxidase-like N-doped carbon nanocages (NC) and peroxidase-like copper oxide (CuO) improved the reaction selectivity in transforming the substrate into the target product by more than 1200 times against the interference of uric acid. The cascade catalytic reaction system was also applicable for transfer from open reactors into a spatially confined microfluidic device, increasing the slope of the calibration curves by approximately 1000-fold with a linear detection range of 2.5 nmol/L to 100 nmol/L and a low limit of detection of 0.77 nmol/L. This work offers a new strategy that achieves significant improvements in selectivity and sensitivity.
Selective separation of phenanthrene (PHE) from aromatic isomer mixtures poses a significant challenge in industry due to the similar physical properties of PHE and its isomer anthracene (ANT). Herein, we report the self-assembly of a water-soluble Pd2L2 cage 1 with a large hydrophobic cavity, formed from novel macrocyclic ligands (L) and cis-Pd(Ⅱ). Cage 1 can selectively encapsulate PHE instead of ANT. Based on host-guest recognition followed by extraction, we achieve a remarkable 99% purity of PHE separation from an equimolar mixture of PHE and ANT using cage 1 in aqueous solution. Importantly, the separation performance of PHE using cage 1 remains unaffected even after five extraction cycles, demonstrating its robustness. This work highlights the potential of supramolecular cages for efficient and cost-effective PHE separation from the isomer ANT in aqueous solutions using such promising host-guest strategy.
The micro-dispersion structure of silica fillers exerts significant influences on the performance characteristics of rubber-based products. How to monitor this parameter is an important issue in the rubber industry, but there is currently no suitable technical solution for numerical monitoring that can be applied in automatic production line. The labeling of silica in rubber is a challenge that bottlenecks the development of numerical quality monitoring technology. In this work, we employed the organometallic europium to modify silica endowing the fluorescence properties for characterization. It provides more feasible solutions for visually studying the relationship between the submicroscopic structure and macroscopic properties of inorganic-filled polymers, and is the key foundation for achieving numerical monitoring of rubber filler qualities in industry.
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