Abstract
Paper-based biosensors based on lateral flow immunoassay (LFI) are promising candidates for POC diagnosis because of their ease of use and rapid target detection. However, the low sensitivity of LFI limits its application, and signal amplification has been used in numerous studies to increase its sensitivity. We developed an advanced trap LFI (α-trapLFI), a simple-to-use sensor, with an additional step for signal amplification. Here, signal amplification is automatically implemented following delayed release of enhancement solution induced by water-soluble polyvinyl alcohol tape. As the polyvinyl alcohol tape is exposed to water, its polymer structure is perturbed (within 5 min), allowing ions to pass through. This new sensor was designed to have a short time delay between the flow of solutions used for the immunoassay and signal amplification. The α-trapLFI was subsequently used to detect cortisol with high sensitivity (9.1 pg∙mL−1) over a broad detection range (0.01–1000 ng∙mL−1) in bodily fluids. Furthermore, an excellent correlation was obtained by analyzing 20 human real saliva samples using this sensor and a conventional ELISA (R2 = 0.90). The new sensor will be helpful in detecting various small molecules for simple, rapid, and portable POC diagnosis of stress disorders.
Highlights
Paper-based biosensors based on lateral flow immunoassay (LFI) are promising candidates for POC diagnosis because of their ease of use and rapid target detection
Biosensors based on a lateral flow immunoassay (LFI) are promising candidates for POC diagnosis, as they are easy to use by non-specialized individuals and enable rapid target detection without specialized equipment[6,7,8]
As the devised method involves the enlargement of AuNPs for signal amplification (Scheme S1), a signal amplification pad loaded with gold ions for signal amplification is placed on the Polyvinyl alcohol (PVA) tape to induce a delayed-release effect
Summary
Paper-based biosensors based on lateral flow immunoassay (LFI) are promising candidates for POC diagnosis because of their ease of use and rapid target detection. As the polyvinyl alcohol tape is exposed to water, its polymer structure is perturbed (within 5 min), allowing ions to pass through This new sensor was designed to have a short time delay between the flow of solutions used for the immunoassay and signal amplification. Most LFI-based biosensors show low sensitivity and cannot provide quantitative r esults[9] To overcome these limitations, several signal amplification methods have been evaluated for use with LFI, including the application of enzymes for additional color-developing r eactions[10,11,12,13] and application of nanoparticles for fluorescent signal enhancement[14,15,16,17]. A highly sensitive LFI method based on a simple structure to delay the release of the signal-amplification solution, without long lag-time procedures, is warranted
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