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Point-of-care testing (POCT) technology is urgently required owing to the prevalence of the Internet of Things and portable electronics. In light of the attractive properties of low background and high sensitivity caused by the complete separation of excitation source and detection signal, the paper-based photoelectrochemical (PEC) sensors, featured with fast in analysis, disposable and environmental-friendly have become one of the most promising strategies in POCT. Therefore, in this review, the latest advances and principal issues in the design and fabrication of portable paper-based PEC sensors for POCT are systematically discussed. Primarily, the flexible electronic devices that can be constructed by paper and the reasons why they can be used in PEC sensors are expounded. Afterwards, the photosensitive materials involved in paper-based PEC sensor and the signal amplification strategies are emphatically introduced. Subsequently, the application of paper-based PEC sensors in medical diagnosis, environmental monitoring and food safety are further discussed. Finally, the main opportunities and challenges of paper-based PEC sensing platforms for POCT are briefly summarized. It provides a distinct perspective for researchers to construct paper-based PEC sensors with portable and cost-effective, hoping to enlighten the fast development of POCT soon after, as well as benefit human society. • The merits of functionalized paper for PEC sensor are introduced. • Photosensitive material and signal amplification strategy of paper-based PEC sensor are discussed. • The application of paper-based PEC sensor in the field of POCT is highlighted. • The limitations and challenges of paper-based PEC sensor are summarized. [ABSTRACT FROM AUTHOR]

In the past few years, point-of-care testing (POCT) technology has crossed the boundaries of laboratory determination and entered the stage of practical applications. Herein, the latest advances and principal issues in the design and fabrication of paper-based bipolar electrode electrochemiluminescence (BPE-ECL) sensors, which are widely used in the POCT field, are highlighted. After introducing the attractive physical and chemical properties of cellulose paper, various approaches aimed at enhancing the functions of the paper, and their underlying principles are described. The materials typically employed for fabricating paper-based BPE are also discussed in detail. Subsequently, the universal method of enhancing BPE-ECL signal and improving detection accuracy is put forward, and the ECL detector widely used is introduced. Furthermore, the application of paper-based BPE-ECL sensors in biomedical, food, environmental and other fields are displayed. Finally, future opportunities and the remaining challenges are analyzed. It is expected that more design concepts and working principles for paper-based BPE-ECL sensors will be developed in the near future, paving the way for the development and application of paper-based BPE-ECL sensors in the POCT field and providing certain guarantee for the development of human health. • Preparation and application prospect of paper-based BPE-ECL sensor are discussed. • Approaches to boost functionalization of paper and existing limitations are described. • Fabricating BPE from classical electrode materials are introduced exhaustively. • Strategies of enhancing ECL signal to improve device sensitivity are displayed. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, point-of-care testing (POCT) techniques have achieved flourishing development in human health monitoring, where paper-based POCT platforms have exhibited superior properties of low cost, easy accessibility and eco-friendliness. For fabrication of paper-based POCT platforms, the pen-on-paper (PoP) strategies through directly writing desired functional materials on paper have been creatively developed in recent years. The PoP strategies are characterized by simplicity, rapid prototyping and do-it-yourself capability, and are also likely to realize scalable manufacturing through integration with software-controlled plotter. In this review, we firstly introduce various kinds of papers and pens employed in the PoP strategies, and then summarize the state-of-art advances of PoP strategies for making paper-based POCT platforms. Subsequently, we discuss the representative applications of PoP strategies for human health monitoring. Conclusions, current challenges and future perspectives of the PoP strategies for human health related POCT uses are finally given. Highlights • A variety of pens and papers involved in pen-on-paper (PoP) strategies are summarized. • The state-of-art of PoP strategies in realizing key steps involved in construction of POCT platforms are reviewed. • Representative applications of PoP strategies in human health monitoring are discussed. • Possible roadmaps can be oriented to move PoP strategies a giant step forward for human health. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication of paper disc interfaced immunodevice for detecting diverse biomarker. • Highly sensitive and affordable disease detection tool. • Validated with range of spiked and real samples. • Universal sensing ability was accessed using C-reactive protein and potato viruses. The detection of specific biomarkers is used in various phases of the diagnosis of plant and human diseases, from prognosis to monitoring. Herein, we report a Prussian blue nanocube-modified immunodevice interfaced with a paper disc for the detection of plant biomarkers via streptavidin-biotin recognition. The detection ability of the immunodevice was assessed using Potato virus X as a model biomarker and analyzed using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The immunodevice displayed excellent performance for Potato virus X detection with a detection limit of 0.92 nM (3S/N). The selectivity of the fabricated Potato virus X immunodevice was investigated using closely associated antigens, such as potato aucuba mosaic virus, Potato virus Y, and Potato virus A. The Potato virus X immunodevice exhibited ∼ 90 % recovery in spiked complex plant samples with a relative error of ∼ 9 %. Furthermore, the immunodevice was used to screen for Potato virus X in 10 samples from potato tubers and leaves. The paper-disc-interfaced immunodevice was also evaluated by detecting other biomarkers, such as potato aucuba mosaic virus in plant diseases and C-reactive protein in human ones. This immunodevice may allow the on-site monitoring of diverse biomarkers by simplifying the current point of care diagnostic tools. [ABSTRACT FROM AUTHOR]

Point-of-care (POC) diagnostics play an important role in delivering healthcare, particularly for clinical management and disease surveillance in both developed and developing countries. Currently, the majority of POC diagnostics utilize paper substrates owing to affordability, disposability, and mass production capability. Recently, flexible polymer substrates have been investigated due to their enhanced physicochemical properties, potential to be integrated into wearable devices with wireless communications for personalized health monitoring, and ability to be customized for POC diagnostics. Here, we focus on the latest advances in developing flexible substrate-based diagnostic devices, including paper and polymers, and their clinical applications. [ABSTRACT FROM AUTHOR]

We report the fabrication of a paper-sensor for quantitative detection of α -amylase activity in human blood serum. Pieces of filter papers were coated with starch–iodine solution leading to an intense blue coloration on the surface. Dispensing α- amylase solution on the starch–iodine coated paper reduced the intensity of the color because of starch-hydrolysis catalyzed by amylase. The variation in the intensity of the color with the concentration of amylase was estimated in three stages: (i) initially, the paper-surface was illuminated with a light emitting diode, (ii) then, the transmitted (reflected) rays emitted through (from) the paper were collected on a photoresistor, and (iii) the variations in the electrical resistance of the photoresistor were correlated with the amylase concentration in analyte. The resistance of photoresistor decreased monotonically with an increase in amylase concentration because the intensity of the reflected (transmitted) rays collected from (through) the paper increased with reduction in the color intensity on the paper surface. Since a specific bio-reaction was employed to detect the activity of amylase, the sensor was found to be equally efficient in detecting unknown quantities of amylase in human blood serum. The reported sensor has shown the potential to graduate into a point-of-care detection tool for α- amylase. [ABSTRACT FROM AUTHOR]

Considerable advances in point-of-care testing (POCT) devices stem from innovations in cellphone (CP)-based technologies, paper-based assays (PBAs), lab-on-a-chip (LOC) platforms, novel assay formats, and strategies for long-term reagent storage. Various commercial CP platforms have emerged to provide cost-effective mobile health care and personalized medicine. Such assay formats, as well as low-cost PBAs and LOC-based assays, are paving the way to robust, automated, simplified, and cost-effective POCT. Strategies have also been devised to stabilize reagent storage and usage at ambient temperature. Nevertheless, successful commercialization and widespread implementation of such clinically viable technologies remain subject to several challenges and pending issues. [ABSTRACT FROM AUTHOR]

COVID-19 is a highly diffuse respiratory infection caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Currently, quantitative real-time polymerase chain reaction (qRT-PCR) technology is commonly used in clinical diagnosis of COVID-19. However, this method is time-consuming and labor-intensive, which is limited in clinical application. Here, we propose a new method for the ultrasensitive and visual detection of SARS-CoV-2 viral nucleic acid. The assay integrates with a paper device and highly efficient isothermal amplification technology - Netlike rolling circle amplification (NRCA), which can reach a limit of detection of 4.12 aM. The paper-based NRCA owns advantages of specificity, portability, visualization and low-cost. Therefore, this method can effectively meet the requirements of point-of-care testing, providing a novel molecular detection technology for clinical diagnosis of COVID-19 and promoting the development of NRCA devices. [Display omitted] ● A paper biosensor was used for ultrasensitive and visual detection of SARS-CoV-2. ● Amplified analysis has been achieved by netlike rolling circle amplification. ● The paper-based NRCA owns advantages of portability, visualization and low-cost. ● The assay can effectively meet the requirements of point-of-care diagnosis of COVID-19. [ABSTRACT FROM AUTHOR]

We first reported a novel visualized instrument-free signal conversion method on paper for cardiovascular biomarker detection based on the coffee-ring effect (CRE). Our strategy was based on the principle that cTnI was captured by DNA probe decorated detection antibody to form sandwich complex, which could hybridize with H1 probes to form G-quadruplex DNAzyme. As a peroxidase mimic, G-quadruplex DNAzyme could catalyze colorimetric reaction and generate colored products, which were converted to the end edge of the paper by evaporation-driven flow, forming a visible colored band. Hence, the resulted colored signals were converted to distance signal by CRE, so that the quantification of cTnI could be measured easily only by a ruler. Our results demonstrated that the length of the colored bands was proportional to the concentration of cTnI, with a limit of detection of 1.0 pg/mL. Furthermore, this strategy not only showed advanced performance to discriminate cTnI from complex samples but also exhibited high accuracy with standard method in real sample. Hence, these results demonstrated that this method established a promising equipment-free and visualized platform for detecting various kinds of genetic diseases and biomarkers, further promoting the development of point-of-care testing (POCT) in biomedicine. • A visual Cardiovascular Biomarker detection strategy was developed. • The resulted colored signals were converted to distance signal by CRE. • This method developed equipment-free and visualized platform. [ABSTRACT FROM AUTHOR]

Paper-based diagnostic assay is quite popular in point-of-care testing (POCT). In this work, we reported a series of hybrid fluorophores based on fluorescein derivatives and investigated their fluorescent properties in detail. To extend the practical application of these hybrid fluorophores, we further constructed the corresponding probes (FN1-FN4) for Cu2+ detection. In comparison with the other three probes, FN4 showed high selectivity and sensitivity, as well as response to Cu2+ within 20 min. Particularly, by introducing this probe into the paper-based device, we could achieve simple, high-throughput, visual and highly sensitive platform for POC detection of Cu2+. Finally, we assessed the paper-based device in real samples such as serum, cytochylema and lake water to demonstrate its promising application. As a result, satisfied performance for Cu2+ detection was achieved, which indicates the great potential of our strategy in the construction of POCT system for detecting analytes. Image 1 • Novel hybrid fluorophores based naphthofulorescein dyes have been synthesized to show excellent fluorescence properties. • Hybrid fluorophores-based paper device for visual detection of Cu2+ has been developed. • Suitable for point-of-care detection, the paper device could visualize high-throughput Cu2+ detection in real samples. [ABSTRACT FROM AUTHOR]