From saliva to SNP: non-invasive, point-of-care genotyping for precision medicine applications using recombinase polymerase amplification and giant magnetoresistive nanosensors

Abstract

Genetic testing is considered a cornerstone of the precision medicine paradigm. Genotyping of single nucleotide polymorphisms (SNPs) has been shown to provide insights into several important issues, including therapy selection...

Longitudinal analysis of anti-SARS-CoV-2 neutralizing antibody (NAb) titers in vaccinees using a novel giant magnetoresistive (GMR) assay

“…We also consider further reduction of assay times to be feasible given past work on similar tests that saw turnaround times of ~15 minutes [37] . Finally, we believe that this assay is a prime candidate for deployment as a point-of-care tool, as has been done with other GMR assays [23] , [37] , [38] . In the future, this neutralizing antibody test could be conducted in a self-contained, single-use cartridge on which all sample and fluid handling would be automated.…”

Rapid, Point-of-Care Host-Based Gene Expression Diagnostics Using Giant Magnetoresistive Biosensors

“…The GMR biosensor chips used in this work comprised an array of 80 multilayer spin-valve nanosensors and were fabricated, as previously described. , Each chip was wire-bonded to a custom-designed printed circuit board (PCB) (Figure S2) that was designed to interface with complementary signal acquisition and conditioning circuitry. , Individual sensors were functionalized with amino-modified single-stranded DNA (ssDNA) capture probes (Table S1) via a surface silanization method described previously. , Briefly, the chip was rinsed sequentially by acetone, methanol, and isopropanol. Then, to ensure that the probes could more effectively bind to the sensor surface, the chip was treated in a bath of 15% hydrogen peroxide (Certified ACS, Sigma-Aldrich) in distilled water for 15 min, then 10% (3-aminopropyl)­triethoxysilane (Sigma-Aldrich) in acetone for 30 min, and then 5% glutaraldehyde (Fisher Scientific) in distilled water for 30 min.…”

“…36,37 Each chip was wire-bonded to a custom-designed printed circuit board (PCB) (Figure S2) that was designed to interface with complementary signal acquisition and conditioning circuitry. 39,43 Individual sensors were functionalized with amino-modified single-stranded DNA (ssDNA) capture probes (Table S1) via a surface silanization method described previously. 48,49 Briefly, the chip was rinsed sequentially by acetone, methanol, and isopropanol.…”

“…An existing on-chip temperature control module was used to implement temperature controlled denaturation and hybridization, facilitating effective binding between the biotinylated amplicons and the surface-bound probes (Figure 2c,d). 39 Control of these modules, as well as GMR signal acquisition and analysis, were implemented using a PCB that was developed based on an earlier iteration of a POC-friendly GMR analyzer (Figure S3a). 39,43 The PCB contained a custom analog front-end and an analog-to-digital converter, which managed signal sampling and conditioning.…”

“…39 Control of these modules, as well as GMR signal acquisition and analysis, were implemented using a PCB that was developed based on an earlier iteration of a POC-friendly GMR analyzer (Figure S3a). 39,43 The PCB contained a custom analog front-end and an analog-to-digital converter, which managed signal sampling and conditioning. An on-board programmable micro-controller unit (ATSAM3X8E, Microchip Technology) was used to enable assay automation, to assist in requisite analysis tasks, and to communicate assay progress/results with the user on a smartphone app using Bluetooth communication.…”