Polydimethylsiloxane-Paper Hybrid Lateral Flow Assay for Highly Sensitive Point-of-Care Nucleic Acid Testing

Abstract

In nucleic acid testing (NAT), gold nanoparticle (AuNP)-based lateral flow assays (LFAs) have received significant attention due to their cost-effectiveness, rapidity, and the ability to produce a simple colorimetric readout. However, the poor sensitivity of AuNP-based LFAs limits its widespread applications. Even though various efforts have been made to improve the assay sensitivity, most methods are inappropriate for integration into LFA for sample-to-answer NAT at the point-of-care (POC), usually due to the complicated fabrication processes or incompatible chemicals used. To address this, we propose a novel strategy of integrating a simple fluidic control strategy into LFA. The strategy involves incorporating a piece of paper-based shunt and a polydimethylsiloxane (PDMS) barrier to the strip to achieve optimum fluidic delays for LFA signal enhancement, resulting in 10-fold signal enhancement over unmodified LFA. The phenomena of fluidic delay were also evaluated by mathematical simulation, through which we found the movement of fluid throughout the shunt and the tortuosity effects in the presence of PDMS barrier, which significantly affect the detection sensitivity. To demonstrate the potential of integrating this strategy into a LFA with sample-in-answer-out capability, we further applied this strategy into our prototype sample-to-answer LFA to sensitively detect the Hepatitis B virus (HBV) in clinical blood samples. The proposed strategy offers great potential for highly sensitive detection of various targets for wide application in the near future.

Improved Analytical Sensitivity of Lateral Flow Assay using Sponge for HBV Nucleic Acid Detection

“…Compared with the structure of unmodified LFA (Fig. 1A ) , the sponge shunt was added in the modified LFA between the conjugation pad and nitrocellulose membrane, which can delay the fluid flow rate to improve the analytical sensitivity 18–20 , because the radius of sponge structure was larger than that of conjugation pad, making the capillary force of sponge less than that of conjugation pad 29 (Fig. 1B).…”

“…Generally, the capillary force P ca treats as the main driven force is analogous to the voltage V in the electrical circuit. The wicking speed Q and fluidic resistance are regarded as the electrical current I and resistance R i , respectively, where μ is the viscosity and the material parameters, such as the length L , width W , height H , permeability K of strips, are experimentally measured and theoretically calculated by our previous method 17, 18 (Table S2). Considering that liquid is quickly added into the sample pad by manual pipetting in experiment, the sample pad is fully wetted and regarded as a liquid pool to supply the sample for connected conjugated pad.…”

“…However, such changes significantly increase the needed sample volume. Additionally, PDMS-paper 18 and hydrogel-paper hybrid material 19 have been integrated into conventional LFAs as a shunt for improving LFA analytical sensitivity through increasing the reaction time of the fluid because of the inverse relationship between the LFA analytical sensitivity and the reaction time 8–10, 12 . However, such hybrid material shunts need complex preparation process and more reagents.…”

Practical High-Performance Lateral Flow Assay Based on Autonomous Microfluidic Replacement on a Film

“…Among POCT devices, paper-based devices have been seen as the ideal platform for point-of-care (POC) diagnostics due to their very low cost, simplicity, and inherent ability to wick fluids. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Fluid transport eliminates expensive pumping instrumentation and complicated handling. 16,17 The porous structure of paper is very convenient for dot-immunobinding assays, and cellulose itself has high affinity to biomolecules.…”

Ultrasensitive indirect competitive ELISA and strip sensor for detection of furazolidone metabolite in animal tissues

“…The ELISAs have been widely used for rapid detection of substances such as low molecular analytes, nucleic acids, proteins, etc. Choi et al, 2016;Pavankumar, Engstrom, Liu, Herthnek, & Nilsson, 2016;Xing et al, 2013;Xing et al, 2015;Xing, Liu, Zhang, Kuang, & Xu, 2014;Yin, Liu, Song, Kuang, & Xu, 2015;Zhang et al, 2013). Many researchers have suggested the immunological detection method for furazolidone metabolite detection.…”