Luo Xu,Fang Yang,Jiagen Li,Qihui Wang,Lin Du,Min Yang,Xiaohong Fu
In this work, an electrochemical sensor based on a highly efficient competitive method is proposed that uses SiO2-PNPG as an adsorbent for the efficient detection of Pb(II) in soil. The silica (SiO2) and N-phenylglycine (NPG) polymer (SiO2-PNPG), synthesized using a one-pot polymer method, was applied to construct specific metal electrochemical sensors with high sensitivity. The high sensitivity and good selectivity were accomplished in the determination of Pb(II) due to the selective penetration and accumulative effect of SiO2-PNPG. The correlation between the current response and the Pb(II) concentration presents a linear range from 2.12 to 15.78 μg mL−1 with a detection limit of 0.166 μg mL−1 (S/N = 3, R2 = 0.9987). The sensitivity, reproducibility and stability of this sensor are promoted due to the facilitated electron transfer.
Herein, a novel bipolar electrode-electrochemiluminescence (BPE-ECL) biosensing strategy was developed, engineered to achieve highly and pathogen-specific detection of Escherichia coli O157:H7 ( E. coli O157:H7) through enzymatic cascade signal transduction. Crucially, this strategy employs β-galactosidase (β-gal) activity as a biomarker signature, wherein the enzymatic hydrolysis of p -nitrophenyl-β-D-galactopyranoside (PNPG) generates electroactive intermediates, p-nitrophenol (pNP). The pNP undergoes a six-electron reduction reaction at the closed BPE cathode electrode and simultaneously oxidizes phosphorus Ru(bpy) 3 2+ at the anode electrode to trigger obvious ECL signal. The ECL signal amplification of enzymatic substrates with mono-, bi-, and tetra-electronic systems is inherently constrained by inefficient electron transfer, resulting in suboptimal sensing performance. In contrast, the PNPG/pNP-based detection platform demonstrates superior sensing capabilities. For indirect quantification of E. coli O157:H7, the ECL intensity was linearly correlated with bacterial concentration. The optimized biosensor, through rigorous tuning of enzymatic catalysis and ECL signal amplification strategies, delivers a wide dynamic range (10(Zhang et al., 2023a 1) –10 6 CFU) and a low detection limit (LOD = 2 CFU) in 200 μL of bacterial samples. The real sample effect was evaluated, and the assay successfully detected E. coli O157:H7 in water, juice, and pure milk. This label-free platform integrates operational simplicity and high specificity, offering a promising solution for on-site monitoring of foodborne pathogens and clinical diagnostics.
Peng-Cheng Guo,Hua-Dan Shen,Jiang-Ji Fang,Tian-Ming Ding,Xiao-Ping Ding,Jun-Feng Liu
An on-line high-performance liquid chromatography–biochemical detection (HPLC-BCD) method, in which compounds separated by HPLC were on-line reacted with enzyme and substrate solutions delivered by flow injection and the enzyme inhibition signal was collected by UV detection, was developed to rapidly screen α -glucosidase inhibitors from green tea extracts in this study. The chromatographic fingerprints and enzyme inhibition profiles of the different brands of green tea could be simultaneously detected by the on-line HPLC-BCD method. Enzyme inhibition profiles were detected by the UV detector at 415 nm based on the reaction of α -glucosidase and p -nitrophenyl α - d -glucopyranoside (PNPG). PNPG (1.25 m m ), α -glucosidase (0.4 U/mL) and the flow rate 0.07 mL/min were applied as optimized parameters to detect α -glucosidase inhibitors in green tea. Four components in green tea showed α -glucosidase inhibition action and three of them were identified as HHDP-galloyl glucose, (−)-epigallocatechin-3-gallate and (−)-epicatechin-3-gallate by HPLC–fourier-transform mass spectrometry (HPLC-FTMS). Two brands of green tea derived from Mengding and Enshi mountainous areas might be superior to the other samples in the prevention and treatment of diabetes owing to their stronger activities of enzyme inhibitors. The proposed on-line HPLC-BCD method could be used to rapidly identify the potential enzyme inhibitors in complex matrixes.
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