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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]

A multi-amplified paper-based electrochemical strategy using Pb 2+ dependent DNAzyme as the recognition unit for Pb 2+ detection was developed. In this work, flower-like reduced graphene (FrGO) was prepared utilizing flower-like ZnO as template, which was first one step grown on the gold nanoparticles modified paper working electrode (Au-PWE). After being treated with acid and then modified with Au, a novel sensor platform named Au/FrGO/Au-PWE with large specific surface area and good electrical conductivity was fabricated. The Mn 2 O 3 nanoparticle-assembled hierarchical hollow spheres (H-Mn 2 O 3 ) was served as nanocarrier to immobilize GOx, HRP and signal strand (S3), resulting to the formation of S3/H-Mn 2 O 3 /HRP/GOx bioconjugations. In the presence of Pb 2+ , the DNAzyme (S1) was activated and the substrate strand (S2) was cleaved. After the incubation with S3/H-Mn 2 O 3 /HRP/GOx in 0.1 M HAc–NaAc solution (pH 4.3) containing 30 mM aniline and 15 mM glucose, a readily measurable “turn-on” electrochemical signal could be measured. On the basis of the signal amplification strategy of Au/FrGO/Au-PWE sensing platform and S3/H-Mn 2 O 3 /HRP/GOx bioconjugations, the developed biosensor exhibited a good linear response toward over a wide range of concentration from 0.005 to 2000 nM. [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]