RESUMO
The COVID-19 pandemic has underscored the critical need for rapid and accurate screening and diagnostic methods for potential respiratory viruses. Existing COVID-19 diagnostic approaches face limitations either in terms of turnaround time or accuracy. In this study, we present an electrochemical biosensor that offers nearly instantaneous and precise SARS-CoV-2 detection, suitable for point-of-care and environmental monitoring applications. The biosensor employs a stapled hACE-2 N-terminal alpha helix peptide to functionalize an in situ grown polypyrrole conductive polymer on a nitrocellulose membrane backbone through a chemical process. We assessed the biosensor's analytical performance using heat-inactivated omicron and delta variants of the SARS-CoV-2 virus in artificial saliva (AS) and nasal swab (NS) samples diluted in a strong ionic solution, as well as clinical specimens with known Ct values. Virus identification was achieved through electrochemical impedance spectroscopy (EIS) and frequency analyses. The assay demonstrated a limit of detection (LoD) of 40 TCID50/mL, with 95% sensitivity and 100% specificity. Notably, the biosensor exhibited no cross-reactivity when tested against the influenza virus. The entire testing process using the biosensor takes less than a minute. In summary, our biosensor exhibits promising potential in the battle against pandemic respiratory viruses, offering a platform for the development of rapid, compact, portable, and point-of-care devices capable of multiplexing various viruses. The biosensor has the capacity to significantly bolster our readiness and response to future viral outbreaks.
RESUMO
Naturally stimulated dynamic ordering-disordering of biomolecules via noncovalent interactions is a commonly occurring phenomenon in biological systems. Herein, we report the effect of induced polarization on the charge carrier dynamics of carbon-quantum-dot-based nano ionic materials (CQD-NIMs) under simulated solar radiation. The solventless liquid-like CQD-NIMs is composed of polystyrenesulfonate (PSS)-passivated CQD as the core-corona system with a polyetheramine (Jeffamine) forming the canopy. The material was observed to behave as a dielectric when placed between two electrodes. Dynamic ordering-disordering of the corona around the CQD surface under induced polarization allowed excess current flow through the solventless material when exposed to simulated solar radiation. Such reversible molecular-assembly-induced photoconducting behavior of the CQDs was characterized with impedance spectroscopy and steady state fluorescence spectroscopy. The concept depicted in the present manuscript may be further developed to design smart light-sensitive molecular switching devices.
