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Covalent organic frameworks (COFs) are a type of crystalline porous polymer composed of light elements through strong covalent bonds. COFs have attracted considerable attention due to their unique designable structures and excellent material properties. Currently, COFs have shown outstanding potential in various fields, including gas storage, pollutant removal, catalysis, adsorption, optoelectronics, and their research in the sensing field is also increasingly flourishing. In this review, we focus on COF‐based sensors. Firstly, we elucidate the fundamental principles of COF‐based sensors. Then, we present the primary application areas of COF‐based sensors and their recent advancements, encompassing gas, ions, organic compounds, and biomolecules sensing. Finally, we discuss the future trends and challenges faced by COF‐based sensors, outlining their promising prospects in the field of sensing. [ABSTRACT FROM AUTHOR]

For epidemic prevention and control, molecular diagnostic techniques such as field‐effect transistor (FET) biosensors is developed for rapid screening of infectious agents, including Mycobacterium tuberculosis, SARS‐CoV‐2, rhinovirus, and others. They obtain results within a few minutes but exhibit diminished sensitivity (<75%) in unprocessed biological samples due to insufficient recognition of low‐abundance analytes. Here, an electro‐enhanced strategy is developed for the precise detection of trace‐level infectious agents by liquid‐gate graphene field‐effect transistors (LG‐GFETs). The applied gate bias preconcentrates analytes electrostatically at the sensing interface, contributing to a 10‐fold signal enhancement and a limit of detection down to 5 × 10−16 g mL−1 MPT64 protein in serum. Of 402 participants, sensitivity in tuberculosis, COVID‐19 and human rhinovirus assays reached 97.3% (181 of 186), and specificity is 98.6% (213 of 216) with a response time of <60 s. This study solves a long‐standing dilemma that response speed and result accuracy of molecular diagnostics undergo trade‐offs in unprocessed biological samples, holding unique promise in high‐quality and population‐wide screening of infectious diseases. [ABSTRACT FROM AUTHOR]

Ascorbic acid, dopamine, and uric acid are important electroactive biomolecules for health monitoring and they coexist in serum or urine. Their quantitative determination by electrochemistry could provide the accurate reference for diseases diagnosis and treatment. However, the traditional electrochemical workstations are too large for on-field inspection. Hence, the design of handheld electrochemical system for the detection of biomolecules is significant for point-of-care testing (POCT). In this paper, a smartphone-based integrated voltammetry system using modified electrode was developed for simultaneous detection of biomolecules. The system contained a disposable sensor, a coin-size detector, and a smartphone equipped with application program. Screen-printed electrodes were used as sensors for the detection, on which reduced graphene oxide and gold nanoparticles were electrochemically deposited by the system. The detector was used with voltammetric methods, in which excitation voltage was applied on the sensors and subsequent current responses were detected. The smartphone is the core component to communicate with the detector, calculate data, and plot voltammograms in real-time. Then, the system was applied to detect standard solutions of the biomolecules and their mixtures as examples. The results showed that the peak currents of each substance increased with higher concentration and the method allowed the discrimination of the different potentials of the studied species. Finally, the practical applications of the system were tested through detections of the biomolecules in artificial urine. The results exhibited that the system could be used to detect electrochemical activity of biomolecules with linear, high sensitivity, and specific responses in point-of-care testing. [ABSTRACT FROM AUTHOR]

With the advantages of high popularity, convenient operation, open-source operation systems, high resolution imaging, and excellent computing capabilities, smartphones have been widely used as the core of detection system for calculation, control, and real-time display. Hence, smartphones play an important role in electrochemical detection and optical detection. Smartphone-based electrochemical systems were combined with screen-printed electrode and interdigital electrodes for in situ detection. The electrodes were modified with biomaterials, chemical materials, and nanomaterials for biosensors and biodetection, such as 3-amino phenylboronic acid nanocomposites, graphene, gold nanoparticles, zinc oxide nanoparticles, carbon nanotubes, proteins, peptides, and antibodies. With the modified electrodes, the smartphone-based impedance system was used to detect acetone, bovine serum albumin, human serum albumin, and trinitrotoluene, while smartphone-based amperometric system was employed to monitor glucose, ascorbic acid, dopamine, uric acid, and levodopa. The smartphone-based electrochemical system for biosensors and biodetection has provided miniaturized and portable alternative for diagnosis, which is promising to find application in point-of-care testing (POCT)., (© 2022. Springer Science+Business Media, LLC, part of Springer Nature.)