Jun Yu,Bin Hu,Pengfei Nie,Xiaohong Shang,Boshuang Zhang,Zhaoyu Tang,Jianmao Yang,Jianyun Liu
Norfloxacin (NX), as one of the most widely used antibiotics, is becoming a potential pollutant in water. Here, the cobalt-decorated nitrogen-rich carbon material containing abundant carbon nanotubes (Co@C-NCNTs) was synthesized by pyrolysis of the Co,Zn bimetal organic frameworks (Co,Zn-MOF). The introduction of Zn led to the formation of abundant CNTs with high aspect ratio and high N-doping in the carbon metrix. The obtained Co@C-NCNTs catalyst was applied to boost non-radical catalysis of peroxymonosulfate for NX degradation with high efficiency. The release of cobalt was greatly inhibited by Co-N interaction and carbon layer protection. The CNTs amount in Co@C-NCNTs and its catalytic activity were tunable with the Zn/Co ratio. At the optimal Zn/Co ratio, the derived Co@C-NCNTs delivered 92% removal of NX in 30 min, significantly higher than the single Co-MOF based catalyst. Free radical quenching experiments and electron paramagnetic resonance demonstrated the singlet 1 O 2 -dominated degradation process of NX accompanied by the •OH and S O 4 − effect. The electrochemical characterization verified that the electron transfer in the PMS system is greatly enhanced due to the presence of Co@C-NCNTs.
Salmonella is one of the most prevalent pathogens causing foodborne diseases. In this study, a novel electrochemical immunosensor was designed for the rapid and accurate detection of Salmonella typhimurium ( S. typhimurium ) in milk. Platinum nanoparticles and Co/Zn-metal–organic framework @carboxylic multiwalled carbon nanotubes in the immunosensor acted synergistically to enhance the sensing sensitivity and stability. The materials and sensors were characterised using X-ray diffractometry, scanning electron microscopy, Fourier-transform infrared spectroscopy, differential pulse voltammetry, cyclic voltammetry, and other techniques. The optimised immunosensor showed a linear response for S. typhimurium concentrations in the range from 1.3 × 10 2 to 1.3 × 10 8 CFU mL −1 , with a detection limit of 9.4 × 10 1 CFU mL −1 . The assay also demonstrates good specificity, reproducibility, stability, and practical application potential, and the method can be extended to other foodborne pathogens.
Wen Zhang,Hongyang Ma,Jinjie Zhan,Muhua Liu,Panpan Zhang,Junhe Gao,Li Yan,Xi Mei
With the increasing environmental degradation, bacterial contamination is threatening human health. Thus, it is crucial to develop an efficient and safe antimicrobial strategy. In this work, the polyacrylonitrile (PAN) nanofiber membranes contained Co/Zn-metal organic framework (Co/Zn-MOF@PAN) were fabricated via electrospinning technique and surface modified method. The optimal preparation condition for nanofiber membranes were further regulated by adjusting 2-methylimidazole (2-MIM) concentration and secondary growth time. The antibacterial activity of Co/Zn-MOF@PAN against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were determined by turbidimetry and plate colony-counting methods. As the 2-MIM concentration and secondary growth time increased, the hydrophilicity and surface roughness of Co/Zn-MOF@PAN nanofiber membranes increased. In addition, when the 2-MIM concentration was 0.16 mol/L, the Co/Zn-MOF@PAN nanofiber membranes had an antibacterial rate of over 99% against E. coli and S. aureus ., and the minimum inhibitory concentration (MIC) value of Co/Zn-MOF@PAN nanofiber membranes was 0.75 mg/mL. It could be indicated that Co/Zn-MOF@PAN nanofiber membranes exhibited an excellent antibacterial effect. The main antibacterial mechanism of nanofiber membranes was that ROS produced by MOFs could destroy the physiological activities of the bacteria lead to death. The Co/Zn-MOF@PAN nanofiber membranes will have a wide range of applications value in the fields of antibacterial packaging materials and sterilization of water resources.
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