Sensitive colorimetric assay for uric acid and glucose detection based on multilayer-modified paper with smartphone as signal readout

Abstract

In this work, a multilayer-modified paper-based colorimetric sensing platform with improved color uniformity and intensity was developed for the sensitive and selective determination of uric acid and glucose with smartphone as signal readout. In detail, chitosan, different kinds of chromogenic reagents, and horseradish peroxidase (HRP) combined with a specific oxidase, e.g., uricase or glucose oxidase (GOD), were immoblized onto the paper substrate to form a multilayer-modified test paper. Hydrogen peroxide produced by the oxidases (uricase or GOD) reacts with the substrates (uric acid or glucose), and could oxidize the co-immoblized chromogenic reagents to form colored products with HRP as catalyst. A simple strategy by placing the test paper on top of a light-emitting diode lamp was adopted to efficiently prevent influence from the external light. The color images were recorded by the smartphone camera, and then the gray values of the color images were calculated for quantitative analysis. The developed method provided a wide linear response from 0.01 to 1.0 mM for uric acid detection and from 0.02 to 4.0 mM for glucose detection, with a limit of detection (LOD) as low as 0.003 and 0.014 mM, respectively, which was much lower than for previously reported paper-based colorimetric assays. The proposed assays were successfully applied to uric acid and glucose detection in real serum samples. Furthermore, the enhanced analytical performance of the proposed method allowed the non-invasive detection of glucose levels in tear samples, which holds great potential for point-of-care analysis. Graphical abstract ᅟ.

Label-Free Colorimetric Detection of Urine Glucose Based on Color Fading Using Smartphone Ambient-Light Sensor

“…Smartphones are convenient, could be widely applied, and offer good users' experience, making them effective instruments for on-site detection [9][10][11]. To date, most smartphone-based types of colorimetric analysis were reported using the phone's camera for directly capturing images from samples [11][12][13][14]. For example, Xu [13] and our group [15] took photos with a smartphone camera for the quantitative detection of blood and urinary glucose through RGB image analysis.…”

“…To date, most smartphone-based types of colorimetric analysis were reported using the phone's camera for directly capturing images from samples [11][12][13][14]. For example, Xu [13] and our group [15] took photos with a smartphone camera for the quantitative detection of blood and urinary glucose through RGB image analysis. However, there are certain issues that arise when a camera is used as a detector, such as smartphone brand, focusing location, distance between camera and samples, and exogenous light pollution [10].…”

Smartphone‐based clinical diagnostics: towards democratization of evidence‐based health care

“…To this end, optical paper‐based biosensors are in particular advantageous because the interfaces can be quite simple. Barcode‐like paper sensors with developed apps for image acquisition and analysis have been demonstrated for applications such as blood typing haematocrit level determination, glucose and uric acid measurements . Multilayer‐modified paper substrates have been adapted with a smartphone read‐out for the detection of L‐lactate in oral fluid and tears .…”

Detection of chikungunya virus‐specific IgM on laser‐cut paper‐based device using pseudo‐particles as capture antigen

“…Techniques involving laser cutting, wax printing or photolithography are often cited . PADs were originally developed for the separation of plasma from whole blood ‐ notably by using glass‐fiber paper, for the detection of heavy metal ions or for the detection of biomolecules such as uric acid and glucose in various biological samples . PADs have also been used for bacterial diagnostics (eg Mycobacterium tuberculosis ) .…”

“…[30][31][32][33][34] PADs were originally developed for the separation of plasma from whole bloodnotably by using glass-fiber paper, 35 for the detection of heavy metal ions 36,37 or for the detection of biomolecules such as uric acid and glucose in various biological samples. 38,39 PADs have also been used for bacterial diagnostics (eg Mycobacterium tuberculosis). 40 More recently, PADs have been developed for arboviruses diagnostics, including Zika and dengue.…”