A lateral flow immunoassay with self-sufficient microfluidic system for enhanced detection of thyroid-stimulating hormone

Abstract

We report a self-sufficient microfluidic paper-based lateral flow immunoassay device (μLFD) for highly sensitive detection of the thyroid-stimulating hormone (TSH). Fabrication of the paper microchannels involves engraving the nitrocellulose membrane with a CO2 laser to create narrow flow paths, which constrain the fluid flow over the test zone. The proposed microchannel modified devices were studied for detection of the TSH using gold nanoparticles as labels. The effect of such microchannel modified LFDs has led to an improvement in sensitivity by nine times and the limit of detection by 6.6 times due to the slow flow rate of the sample compared with the traditional LFD. In addition, the binding of gold nanoparticles over the test line is more uniform in the case of the μLFD, thus minimizing leading-edge effects, resulting in more accurate quantitative analysis. The proposed strategy offers great potential for multiplex detection of biomarkers with increased sensitivity without introducing any hydrophobic materials to the LFD.

Fluorescent nanodiamond immunosensors for clinical diagnostics of tuberculosis

“…After optimizing assay conditions, we examined whether detection sensitivity could be improved by altering the nitrocellulose membrane configuration (such as the width). 30,31 In conventional studies and commercial setups, a nitrocellulose membrane strip of 4 mm wide is typically used (Fig. 4a).…”

Strip modification and alternative architectures for signal amplification in nanoparticle-based lateral flow assays

“…Carbon dioxide laser patterning has also been proposed as an alternative to hydrophobic materials, so as to create thin flow paths over the detection pad, reaching a sensitivity enhancement of around 9-fold [24]. Such laser patterning offers promising advantages related to high reproducibility and lower unspecific adsorption of proteins, together with bulk manufacturing possibilities.…”

Mechanically Compressed Barriers Improve Paper-Based Lateral Flow Assay Sensitivity for COVID-19 Nucleic Acid Detection

“…In the case of chemical modifications, increasing the electrolyte strength, 18 modification of nitrocellulose (NC) membrane with cellulose nanofibers, 19 addition of chitosan, 20 use of spin-enhanced nanodiamond, 21 self-assembling of gold nanoparticles following the layer-by-layer concept, 22 using potassium alum and animal glue as sizing materials for creating barriers, 23 and laser-patterned geometric barriers influencing the flow dynamics by increasing binding time 24 are few among many other ways. In contrast to chemical modifications, some easy and convenient physical methods are also prominent for LFA sensitivity improvement, such as increasing the sample concentration by paper-based dialysis, 25 use of CO 2 laser to create narrow flow path, 26 and laser-direct write (LDW) technique, which is responsible for lowering the flow rate of liquid photopolymers, 27 and the detection pad width and test line position impact the flow velocity and reaction rate kinetics affecting the limit of detection (LOD) and test-line color intensity. 28 To improve the LFA sensitivity, some physiochemical modifications were made targeting the flow rate or velocity, flow pattern, flow distribution, and reaction rate kinetics.…”

“…Ultimately, these methods were used to slow down the sample flow rate and increase the biorecognition time between the target molecules and capture molecules. Examples include the sponge-based method, PDMS-barrier concept, hydrogel-paper hybrid method, wax-printed pillars barrier, narrowing flow path, wax impregnated line barrier, and PVA dam . The first biorecognition (labeled-gold nanoparticles to bind the target) time is increased by placing the barrier between the conjugate pad and test zone; while the second biorecognition (the target/labeled-gold nanoparticles to bind the capture antibody or nucleic acid probes) time is increased by placing the barrier between the test and control zones .…”