Respiratory virus infections continue to pose major public health and economic threats worldwide. Airborne transmission via virus-laden aerosols is a dominant route for the transmission of respiratory viruses, including SARS-CoV-2, influenza viruses and respiratory syncytial virus (RSV). Despite the demonstrated significance of disease transmission via aerosols, techniques for direct, real-time detection of respiratory virus aerosols have remained elusive. The central goal of my doctoral research is to develop integrated platforms focusing on rapid and point-of-care testing (POCT) of different respiratory pathogens, aiming to overcome the limitations of conventional viral diagnostics.
Towards this goal, the first part of my research focused on a non-invasive, point-of-care testing platform that directly detects SARS-CoV-2 aerosols in as little as two exhaled breaths of patients and will generate test results in under 60 seconds. Itintegrates a hand-held breath aerosol collection device and a llama-derived nanobody specific to SARS-CoV-2 spike-protein bound to an ultrasensitive micro-immunoelectrode (MIE) biosensor. The MIE biosensor detects the oxidation of tyrosine amino acids present in the spike protein of SARS-CoV-2 using square wave voltammetry. Laboratory and clinical trial results were within 20% of those obtained using standard testing methods. Our testing platform provides a rapid and non-invasive alternative to conventional viral diagnostics and holds the potential to be adapted for multiplexed detection of different respiratory viruses.
Parallel to the Breath Aerosol analyzer platform, I worked on the development of an indoor pathogen Air Quality (pAQ) monitor that couples a custom high-flow batch-type wet wall cyclone particle-into-liquid sampler (PILS) with same MIE biosensor technology. Real-time surveillance of airborne SARS-CoV-2 virus is a technological gap that has eluded the scientific community since the beginning of the COVID-19 pandemic. The wet cyclone showed comparable or better virus sampling performance than commercially available samplers. Laboratory experiments demonstrate a device sensitivity of around 80% and a detection limit of 7-35 viral RNA copies/m3 of air, highlighting its potential for point-of-need surveillance of SARS-CoV-2 variants in indoor environments.
Building upon these platforms, my current work focuses on optimizing the biosensing interface itself to support broader pathogen detection. A critical issue in the field deployment of these sensors is biofouling, caused due to nonspecific adsorption of proteins and other biomolecules onto the sensor surface in complex environments. To overcome this, I am developing biofouling-resistant electrochemical capacitive biosensors (ECBs) tailored for robust performance in complex biological fluids like saliva, nasal fluid, and environmental swabs from farms—settings where respiratory virus detection is critically needed. The ECB employs a novel hybrid sensing interface composed of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS or PP) and reduced graphene oxide (rGO). It offers excellent conductivity, antifouling and capacitive properties. We employed the rGO:PP ECB for rapid and label-free detection of influenza A viruses, primarily the avian influenza H5N1 and swine origin influenza H1N1 virus. Functionalized with strain-specific aptamers for the influenza A viruses, the ECB achieves detection in under 5 minutes, with low limits of detection (<50 copies/mL for both influenza strains). Critically, interference testing in complex biological fluids and environmental samples demonstrated minimal signal degradation, highlighting the robust and biofouling-resistant nature of the rGO:PP interface. This addresses a major challenge in field-deployable biosensing.
Our current objective is to scale the ECB technology into a multiplexed biosensor for simultaneous detection of up to 25 respiratory pathogens, including SARS-CoV-2, influenza viruses, and RSV. Each working electrode will be functionalized with a distinct antibody/aptamer to provide specificity for one of the target pathogens, and an additional control electrode will be included. Preliminary results using a 4-target panel (SARS-CoV-2, RSV, and two influenza A strains) show excellent sensitivity and negligible cross-reactivity. This scalable, high-throughput approach could redefine on-site diagnostics for both clinical and public health surveillance.
Overall, these objectives on developing the breath aerosol analyzer, pAQ monitor, biofouling-resistant ECB and multiplexed biosensor demonstrate an efficient end-to-end framework for respiratory virus detection. My research integrates aerosol technology, material science and electrochemistry to tackle the outstanding challenges limiting current POCT and environmental diagnostics. These innovations have the potential to revolutionize virus detection by enhancing accuracy, speed, and affordability, ultimately contributing to improved public health outcomes.