Triazine-based covalent-organic framework embedded with cuprous oxide as the bioplatform for photoelectrochemical aptasensing Escherichia coli

Ultrasensitive detection of Vibrio parahaemolyticus based on boric acid-functionalized Eu (III)-based metal-organic framework

This study intends to create a ratiometric fluorescence probe utilizing aptamers for the detection of Vibrio parahaemolyticus (V. parahaemolyticus) in aquatic products. In this design, aptamer-functionalized magnetic nanoparticles specifically capture V. parahaemolyticus, while boric acid on Eu (III)-Based Metal-Organic Framework (Eu-MOF) interacts with glycolipids present on bacterial cells, thereby achieving dual recognition of V. parahaemolyticus. This fluorescent probe quantitatively detects V. parahaemolyticus by measuring the intensity of ratio fluorescence. The sensor demonstrates a detection range from 77 to 7.7 × 107 CFU/mL, possessing a detection threshold down to 1 CFU/mL. Moreover, the developed method based on Eu-MOF had been successfully applied to real samples. To achieve rapid on-site detection of V. parahaemolyticus, the study designed a portable smartphone sensor that confirms its capability for rapidly detecting pathogens and contributes significantly to establishing a system for regulating safety in detecting food and environment.

A review of research progress on COF-based biosensors in pathogen detection

Despite the availability of various detection tools, the rapid identification and accurate detection of pathogens remain a major challenge in public health management. Covalent organic frameworks (COFs), which are crystalline conjugated organic polymers with considerable application potential, offer unique advantages in several fields owing to their highly ordered structure, large specific surface area, stable chemical properties, and tunable pore microenvironment. In recent years, with the rapid development of biosensing technology, COF application in the field of pathogen detection has attracted extensive attention. Herein, the properties, applications, and synthesis methods of COFs are briefly described, and the application types and basic principles of COFs in building an efficient and sensitive pathogen detection platform are emphatically discussed. Overall, we analyze the current challenges associated with COF-based biosensors in pathogen detection and look forward to their broad application prospects in biomedicine and public health in future.

Recent advances in metallic and metal oxide nanoparticle-assisted molecular methods for the detection of Escherichia coli

The detection of E. coli is of irreplaceable importance for the maintenance of public health and food safety. In the field of molecular detection, metal and metal oxide nanoparticles have demonstrated significant advantages due to their unique physicochemical properties, and their application in E. coli detection has become a cutting-edge focus of scientific research. This review systematically introduces the innovative applications of these nanoparticles in E. coli detection, including the use of magnetic nanoparticles for efficient enrichment of bacteria and precise purification of nucleic acids, as well as a variety of nanoparticle-assisted immunoassays such as enzyme-linked immunosorbent assays, lateral flow immunoassays, colorimetric methods, and fluorescence strategies. In addition, this paper addresses the application of nanoparticles used in nucleic acid tests, including amplification-free and amplification-based assays. Furthermore, the application of nanoparticles used in electrochemical and optical biosensors in E. coli detection is described, as well as other innovative assays. The advantages and challenges of the aforementioned technologies are subjected to rigorous analysis, and a prospective outlook on the future direction of development is presented. In conclusion, this review not only illustrates the practical utility and extensive potential of metal and metal oxide nanoparticles in E. coli detection, but also serves as a scientific and comprehensive reference for molecular diagnostics in food safety and public health.

Photocatalytic Organic Semiconductor-Bacteria Imprinted Polymers for Highly Selective Determination of Staphylococcus aureus at the Single-Cell Level

This work utilized a combination of photocatalytic organic semiconductors and bacteria to create a photocatalytic organic semiconductor-bacterial biomixture system based on a bacteria imprinted polymers (OBBIPs-PEC) sensor, for the detection of S. aureus with high sensitivity in "turn-on" mode at the single-cell level. This outstanding sensor arises from an integration of two different types of semiconductor materials to form heterojunctions. As well this sensor involves combining a semiconductor material with cationic side chains and an electron transport chain within a natural cellular environment, in which the cationic side chain of poly(fluorene-co-phenylene) organic semiconductor at 2-(4-mesyl-2-nitrobenzoyl)-1,3-cyclohexanedione (PFP-OC@MNC) demonstrated the ability to penetrate the cell membrane of S. aureus and interact with specific binding sites through electrostatic interactions. As the cavities in the BIPs were occupied by S. aureus, during light irradiation, the electrons stimulated by the photoexcitation process in the manufactured PFP-OC@MNC semiconductors were successfully transmitted to S. aureus, where these electrons played a role in the regeneration of NADH and FADH2, and then the presence of S. aureus acted as a proficient electron acceptor for photoexcited electrons; thereby the PEC response of the OBBIPs-PEC sensor was significantly enhanced. Of note, it exhibited high selectivity for S. aureus over other bacteria and maintained excellent performance in complex matrices, distinguishing S. aureus with concentrations as low as 10 CFU/mL. This work dramatically reduces the influence of interference factors in the traditional mode and offers a powerful way for microorganism detection in food and environmental fields.

Magnetic relaxation switch biosensor for detection of Vibrio parahaemolyticus based on photocleavable hydrogel

BACKGROUND

Foodborne pathogens, particularly Vibrio parahaemolyticus (VP) found in seafood, pose significant health risks, including abdominal pain, nausea, and even death. Rapid, accurate, and sensitive detection of these pathogens is crucial for food safety and public health. However, existing detection methods often require complex sample pretreatment, which limits their practical application. This study aims to overcome these limitations by developing a label-free magnetic relaxation switch (MRS) biosensor for the detection of VP, utilizing a photocleavable sol-gel phase transition system for improved efficiency and accuracy.

RESULTS

In this work, a tag-free magnetic relaxation switch (MRS) biosensor was designed for the detection of Vibrio parahaemolyticus (VP), based on a photocleavable sol-gel phase transition system. A large amount of lithium acyl hypophosphite (LAP), gold nanoparticles (AuNPs), and single-stranded DNA (ssDNA) loaded on the surface of Ti3C2Tx MXene acted as the signal unit LAP-MXene@AuNPs-ssDNA. The pipette tip served as a reaction vessel, and when VP was present, Apt specifically captured VP and released the signal units. The released signal units were then injected into the low-field nuclear magnetic resonance (LF-NMR) test solution, a gel formed by crosslinking of disulfide bonds. The gel was cleaved by LAPs on the signal units under ultraviolet (UV) irradiation, triggering a gel-sol phase transition, which increased transverse relaxation time (T2), thus enabling the detection of VP. Under the optimal experimental conditions, the linear range and detection limit for VP were 102 ∼ 108 CFU/mL and 10 CFU/mL, respectively.

SIGNIFICANCE AND NOVELTY

The simplified biometric identification process in the pipette tip reduces errors from multiple sample transfers, enhancing efficiency. The use of photocleavable hydrogel for signal output eliminates issues associated with magnetic material aggregation, significantly improving detection precision. The assay is of good selectivity, stability reproducibility, and convenience, having a broad application prospect in the rapid detection of pathogenic bacteria in the field.

Synergistic effect of 2D covalent organic frameworks confined 0D carbon quantum dots film: Toward molecularly imprinted cathodic photoelectrochemical platform for detection of tetracycline

The development of high photoactive cathode materials combined with the formation of a stable interface are considered important factors for the selective and sensitive photoelectrochemical (PEC) detection of tetracycline (TC). Along these lines, in this work, a novel type II heterostructure composed of two-dimensional (2D) covalent organic frameworks confined to zero-dimensional (0D) carbon quantum dots (CDs/COFs) film was successfully synthesized using the rapid in-situ polymerization method at room temperature. The PEC signal of CDs/COFs was significantly amplified by improving the light absorption and electron transfer capabilities. Furthermore, a cathodic molecularly imprinted PEC sensor (MIP-PEC) for the detection of TC was constructed through fast in-situ Ultraviolet (UV) photopolymerization on the electrode. Finally, a "turn-off" PEC cathodic signal was achieved based on the selective recognition of the imprinted cavity and the mechanism of steric hindrance increase. Under optimal conditions, the proposed sensor demonstrated a wide linear relationship with TC in the concentration range of 5.00 × 10-12-1.00 × 10-5 M, with a detection limit as low as 6.00 × 10-13 M. Meanwhile, excellent stability, selectivity, reproducibility, and applicability in real river samples was recorded. Our work provides an effective and rapid in situ construction method for fabricating highly photoactive cathode heterojunctions and uniform stable selective MIP-PEC sensing interfaces, yielding accurate antibiotics detection in the environment.

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.

A review of recent advancement in covalent organic framework (COFs) synthesis and characterization with a focus on their applications in antibacterial activity

The primary objective of this review is to present a comprehensive examination of the synthesis, characterization, and antibacterial applications of covalent organic frameworks (COFs). COFs represent a distinct category of porous materials characterized by a blend of advantageous features, including customizable pore dimensions, substantial surface area, and adaptable chemical properties. These attributes position COFs as promising contenders for various applications, notably in the realm of antibacterial activity. COFs exhibit considerable potential in the domain of antibacterial applications, owing to their amenability to functionalization with antibacterial agents. The scientific community is actively exploring COFs that have been imbued with metal ions, such as copper or silver, given their observed robust antibacterial properties. These investigations strongly suggest that COFs could be harnessed effectively as potent antibacterial agents across a diverse array of applications. Finally, COFs hold immense promise as a novel class of materials for antibacterial applications, shedding light on the synthesis, characterization, and functionalization of COFs tailored for specific purposes. The potential of COFs as effective antibacterial agents beckons further exploration and underscores their potential to revolutionize antibacterial strategies in various domains.