Nanoparticle-Supported Rapid Electronic Detection (NasRED): a Versatile Platform Technology for Reliable, Rapid, Affordable Diagnostics

Accurate and timely diagnostics are essential for effective disease management. However, existing platforms face a trade-off between centralized accuracy and rapid assay speed. Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) require washing, labeling, extensive sample preparation, expensive instrumentation, and hours-to-day turnaround times, limiting their adoption in resource-limited settings. This dissertation presents Nanoparticle-Supported Rapid Electronic Detection (NasRED), a biosensing platform that overcomes these challenges by enabling rapid, highly sensitive, and cost-effective biomolecular detection. NasRED utilizes functionalized gold nanoparticles (AuNPs), whose analyte-dependent aggregation modulates solution turbidity, generating an optical signal. Engineered centrifugation and vortex-driven fluidic forces accelerate reaction kinetics, enhancing nanoparticle interactions in a quasi-equilibrium state. A portable (<$30) optoelectronic readout system improves detection sensitivity and reduces reliance on large-scale instrumentation. NasRED was validated across diverse applications: infectious disease detection (SARS-CoV-2), food safety (Shiga toxin, Stx2), agricultural biosecurity (African swine fever virus, ASFV), and cancer prognosis (Thrombospondin-2, THBS2). For SARS-CoV-2 antigen and antibody quantification, NasRED demonstrated a limit of detection (LoD) of ~51 aM (8 fg/mL) in PBS (>3,000 times more sensitive than ELISA), ~71 aM (10 fg/mL) in serum, and ~250 aM (38 fg/mL) in diluted whole blood. It also enabled a competitive neutralization assay to assess human serum potency against SARS-CoV-2 variants, including Gamma and Omicron. For foodborne pathogen detection, NasRED, functionalized with designed ankyrin repeat proteins (DARPins), achieved attomolar sensitivity for Stx2 across biological matrices, distinguishing STX2 subtypes and Shiga toxin-producing E. coli (STEC) variants in 8-hour cultures. In oncology applications, it achieved femtomolar sensitivity for THBS2, spanning five orders of magnitude, differentiating it from CA 19-9 and BSA. In ASFV diagnostics, NasRED detected P72 and P30 antigens and antibodies in porcine serum, supporting early and concurrent detection strategies. With attomolar sensitivity, rapid processing (<30 min), and affordability (<$3/test, <$30 readout system), NasRED is scalable for global health, pandemic prevention, vaccine evaluation, food safety, and disease surveillance. The platform has reached technological maturity for commercialization through ASU’s Skysong Innovations and REDX Diagnostics, demonstrating real-world impact.