Main content area

Microfluidic Distance Readout Sweet Hydrogel Integrated Paper-Based Analytical Device (μDiSH-PAD) for Visual Quantitative Point-of-Care Testing

Wei, Xiaofeng, Tian, Tian, Jia, Shasha, Zhu, Zhi, Ma, Yanli, Sun, Jianjun, Lin, Zhenyu, Yang, Chaoyong James
Analytical chemistry 2016 v.88 no.4 pp. 2345-2352
capillarity, cocaine, correlation, crosslinking, diagnostic techniques, environmental monitoring, enzymatic reactions, glucan 1,4-alpha-glucosidase, glucose, glucose oxidase, health services, hydrocolloids, hydrogen peroxide, hydrophilicity, oligonucleotides, peroxidase, urine
A disposable, equipment-free, versatile point-of-care testing platform, microfluidic distance readout sweet hydrogel integrated paper-based analytical device (μDiSH-PAD), was developed for portable quantitative detection of different types of targets. The platform relies on a target-responsive aptamer cross-linked hydrogel for target recognition, cascade enzymatic reactions for signal amplification, and microfluidic paper-based analytic devices (μPADs) for visual distance-based quantitative readout. A “sweet” hydrogel with trapped glucoamylase (GA) was synthesized using an aptamer as a cross-linker. When target is present in the sample, the “sweet” hydrogel collapses and releases enzyme GA into the sample, generating glucose by amylolysis. A hydrophilic channel on the μPADs is modified with glucose oxidase (GOx) and colorless 3,3′-diaminobenzidine (DAB) as the substrate. When glucose travels along the channel by capillary action, it is converted to H₂O₂ by GOx. In addition, DAB is converted into brown insoluble poly-3,3′-diaminobenzidine [poly(DAB)] by horseradish peroxidase, producing a visible brown bar, whose length is positively correlated to the concentration of targets. The distance-based visual quantitative platform can detect cocaine in urine with high selectivity, sensitivity, and accuracy. Because the target-induced cascade reaction is triggered by aptamer/target recognition, this method is widely suitable for different kinds of targets. With the advantages of low cost, ease of operation, general applicability, and disposability with quantitative readout, the μDiSH-PAD holds great potential for portable detection of trace targets in environmental monitoring, security inspection, personalized healthcare, and clinical diagnostics.