Molecularly imprinted Photoelectrochemical sensor for Escherichia coli based on Cu:ZIF-8/KZ3TTz heterojunction.

Herein, a signal stable molecularly imprinted photoelectrochemical (MIP-PEC) sensing platform was designed to sensitively detect Escherichia coli by incorporating polythiophene film with Cu: ZIF-8/KZ3TTz heterojunction. Attributed to the formation of a staggered type II heterostructure between KZ3TTz and Cu: ZIF-8 semiconductors, the Cu: ZIF-8/KZ3TTz heterojunction exhibited stable and significant cathode PEC response. Impressively, selective MIP film was grown on the surface of Cu: ZIF-8/KZ3TTz/GCE by electro-polymerization of 2,2-Dimethyl-5-(3-thienyl)-1,3-dioxane-4,6-dione (DTDD) in the presence of E. coli. After removing E. coli, more electrons were transferred to the electrolyte solution through the imprinting cavity on the MIP film, which was eliminated by O2 in the electrolyte, causing further enhancement of the cathode PEC response. On the contrary, when the imprinted cavity was filled with E. coli, the cathodic PEC response gradually decreased due to steric hindrance effect. The sensor showed excellent linearity in the range of 101 to 108 CFU/mL with a detection limit of 4.09 CFU/mL (S/N = 3). This strategy offered a novel approach for pathogenic bacteria detection in food safety and environmental monitoring.

Photoelectrochemical sensor for the detection of Escherichia coli O157:H7 based on TPA-NO2 and dual-functional polythiophene films.

The detection of Escherichia coli (E. coli) is of great significance for the environment and human health. Herein, a photoelectrochemical (PEC) detection strategy based on molecularly imprinted polymers (MIPs) was proposed for the sensitive detection of E. coli. 4,4',4″-Trinitrotriphenylamine (TPA-NO2) was prepared using a simple nitration reaction. Subsequently, MIP films were polymerized on the surface of TPA-NO2 using 1,3-dihydrothieno[3,2-d]pyrimidine-2,4-dione as the functional monomer with the dual functions of specific recognition and sensitization. The linear range was 10-108 CFU/mL and the limit of detection was 10 CFU/mL. It showed favorable recoveries in real sample tests of milk, orange juice and tomato. Additionally, the ability of functional monomers to bind excellently with E. coli was verified using molecular docking techniques. This research provided broader possibilities for constructing MIPs-PEC sensors and analyzing the interaction mechanism between E. coli and functional monomers.

Determination of nitrite in food based on its sensitizing effect on cathodic electrochemiluminescence of conductive PTH-DPP films.

Herein, a novel strategy for electrochemiluminescence (ECL) detection of nitrite based on its sensitization effect on cathode ECL emission of 3,6-di(2-thienyl)-2,5-dihydropyrrolo [3,4-c] pyrrole-1,4-dione (TH-DPP) polymeric films (PTH-DPP) was formulated, by means of a one-step electropolymerization of TH-DPP with a short time on the glassy carbon electrode (GCE). It was shown that the PTH-DPP film-modified GCE exhibited a strong ECL response when S2O82- was used as a co-reactant. The ECL emission could be greatly enhanced by PTH-DPP with nitrite in a K2S2O8/PBS solution system and occurred at a relatively lower potential in comparison with traditional cathode ECL emitter, leading to high sensitivity and good selectivity. The ECL sensor exhibits excellent linear relationship in the ranges of 0.3 to 100 µM and 100 to 1000 µM for nitrite detection, with an outstanding detection limit of 0.08 µM (S/N = 3). The ECL sensor provides an impressive outcome for the detection of practical samples.

Construction of reversible enol-to-keto-to-enol tautomerization covalent organic polymer for sensitive, selective and multi-channel detection of iron (III).

As an important element in organism, the lack and excess of ferric ions (Fe3+) may lead to an extensive range of diseases presenting with distinct clinical manifestations. In our design, a multi-channel probe with reversible enol-to-keto-to-enol tautomerization for the specific recognition and high sensitivity detection of Fe3+ was prepared. This paper reported a novel Cop-NC probe, Tris (4-formylphenyl) amine bearing 1,4-cyclohexanedione groups, which provides binding site for Fe3+ and also contributes both fluorescent and electrochemical signals. The as-synthesized Cop-NC exhibit intense fluorescence under an excitation wavelength at 378 nm with a quantum yield of 26%. Results of spectroscopic measurement show that Fe3+ can significantly cause a "Switch-off" fluorescence intensity effect. Simultaneously, the addition of Fe3+ can cause a "Switch-on" effect in electrochemical channel. It has realized the detection of Fe3+ with concentration as low as 0.4 µM and 1.0 nM in the fluorescence channel and redox channel, respectively. The development of the joint probe with multi-channel signals provides a more convenient and rapid detection method for food, medical treatment, environmental monitoring and other fields.

Non-enzymatic electrochemical detection of glucose using Ni-Cu bimetallic alloy nanoparticles loaded on reduced graphene oxide through a one-step synthesis strategy.

In this work, Ni-Cu bimetallic alloy nanoparticles supported on reduced graphene oxide (Ni-Cu ANPs/RGO) was successfully fabricated through a one-step hydrothermal synthesis method, where simultaneous reduction of graphene oxide, nickel salt and copper salt was performed, and relevant characterization studies were executed. This synthetic method does not require surfactants and high temperature treatment, and is recommended as a green, convenient and effective way to produce composites. The unique two-dimensional architecture of the RGO provides a large specific surface area, contributing to loading more Ni-Cu ANPs, while the uniformly distributed Ni-Cu bimetallic alloy nanoparticles enhance the electrocatalytic performance of glucose oxidation. The non-enzymatic glucose biosensor based on Ni-Cu ANPs/RGO showed a wide linear range (from 0.01 µM to 30 µM), low detection limit (0.005 µM), and excellent sensitivity (1754.72 µA mM-1 cm-2). More importantly, the high reliability and the excellent selectivity in actual sample detection will broaden its practical application in electrochemical sensing.

Bacterial Detection and Elimination Using a Dual-Functional Porphyrin-Based Porous Organic Polymer with Peroxidase-Like and High Near-Infrared-Light-Enhanced Antibacterial Activity.

The efficient fabrication of multifunctional nanoplatforms for bacterial detection and elimination is of great importance in nanobiotechnology. A new porphyrin-based porous organic polymer, FePPOPBFPB, was synthesized via the reaction between pyrrole and 4-{2,2-bis[(4-formylphenoxy)methyl]-3-(4-formylphenoxy) propoxy} benzaldehyde (BFPB). The C-centric tetrahedral structure of BFPB promoted the formation of FePPOPBFPB with a 3D interconnected porous structure, high specific surface area, and plentiful surface catalytic active sites. The adjustable structural alkyl chain also enhanced the absorption capability of FePPOPBFPB in the long-wavelength visible and near-infrared regions (NIR). FePPOPBFPB exhibited excellent peroxidase-like activity toward a representative peroxidase substrate, 3,3',5,5'-tetramethylbenzidine (TMB) with H2O2. Utilizing these features, a rapid and visual detection of Staphylococcus aureus (S. aureus) based on FePPOPBFPB was established and exhibited high sensitivity and stability. Combining the catalysis with near-infrared-light (NIR) absorption, FePPOPBFPB can effectively catalyze the decomposition of biologically relevant concentrations of H2O2 to produce vast amounts of •OH radicals via the photo-Fenton reaction, which avoids the utilization of high toxic concentrations of H2O2. On the basis of these satisfactory features, FePPOPBFPB had a conspicuous bactericidal performance against S. aureus under NIR irradiation. To our knowledge, this is the first example of a porphyrin-based porous organic polymer antibacterial agent. The main reactive oxygen species (ROS) produced in this system and the possible antibacterial mechanism of FePPOPBFPB was also proposed through a series of experiments.

Visible-light-driven photo-Fenton degradation of organic pollutants by a novel porphyrin-based porous organic polymer at neutral pH.

Developing novel heterogeneous photo-Fenton catalysts with high efficiency and stability, driven by visible-light rather ultraviolet light at neutral pH has been a major challenge for degradation of organic pollutants. In this work, we successfully synthesized a metalloporphyrin-based porous organic polymer (FePPOP-1) by the Sonogashira cross-coupling reaction. UV-vis absorption spectra showed FePPOP-1 exhibits a significant coverage of the natural solar irradiance spectrum. As a result, the prepared FePPOP-1 has a significantly enhanced photocatalytic activity for the visible-light-driven degradation of methylene blue. By using only 4 mg of FePPOP-1 as a catalyst, it was found that 50 mL of organic wastewater containing 70 ppm MB could be totally degraded in 80 min even at neutral pH. The effects of the initial MB, H2O2 concentrations, pH value and common ions on MB degradation were studied in detail. Both the catalytic mechanism of FePPOP-1 and the degradation route of MB were also proposed.