ABSTRACT
In 2019, a worldwide pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged. SARS-CoV-2 is the deadly microorganism responsible for coronavirus disease 2019 (COVID-19), which has caused millions of deaths and irreversible health problems worldwide. To restrict the spread of SARS-CoV-2, accurate detection of COVID-19 is essential for the identification and control of infected cases. Although recent detection technologies such as the real-time polymerase chain reaction delivers an accurate diagnosis of SARS-CoV-2, they require a long processing duration, expensive equipment, and highly skilled personnel. Therefore, a rapid diagnosis with accurate results is indispensable to offer effective disease suppression. Nanotechnology is the backbone of current science and technology developments including nanoparticles (NPs) that can biomimic the corona and develop deep interaction with its proteins because of their identical structures on the nanoscale. Various NPs have been extensively applied in numerous medical applications, including implants, biosensors, drug delivery, and bioimaging. Among them, point-of-care biosensors mediated with gold nanoparticles (GNPSs) have received great attention due to their accurate sensing characteristics, which are widely used in the detection of amino acids, enzymes, DNA, and RNA in samples. GNPS have reconstructed the biomedical application of biosensors because of its outstanding physicochemical characteristics. This review provides an overview of emerging trends in GNP-mediated point-of-care biosensor strategies for diagnosing various mutated forms of human coronaviruses that incorporate different transducers and biomarkers. The review also specifically highlights trends in gold nanobiosensors for coronavirus detection, ranging from the initial COVID-19 outbreak to its subsequent evolution into a pandemic.
ABSTRACT
A biocompatible natural polysaccharide (PSP001) isolated from the fruit rind of Punica granatum was conjugated with L-cysteine (Y) to be used as a skeleton for the fabrication of fluorescent gold nanoclusters (AuNCs) represented as PSP-Y-AuNCs. With an average size of ~ 6 nm, PSP-Y-AuNCs demonstrated high quantum yield (31%), with a pH-sensitive fluorescence emission behavior. An emission maximum of 520 nm was obtained at acidic pH, which was blue shifted with increasing pH. This feature provides the possibilities for accurate ratiometric pH imaging. The PSP-Y-AuNCs not only demonstrated excellent biocompatibility with cancer cells and isolated peripheral lymphocytes and red blood cells but also demonstrated to be an active molecular imaging probe with appealing cellular uptake efficiency. The investigations with BALB/c mice further confirmed the non-toxic nature and in vivo imaging potential of the AuNCs. Estimation of the bio-distribution on solid tumor bearing syngeneic murine models revealed a tumor-targeted enhanced fluorescence emission pattern which is attributed to the pH responsive fluorescence behavior and the acidic microenvironment of the tumor. These findings were further confirmed with an impressive tumor accumulation pattern displayed in a xenograft of human cancer bearing nude mice. On account of their impressive biocompatibility and photophysical features, PSP-Y-AuNCs can exploited for the real-time fluorescence imaging of cancer tissues. Graphical abstract Fluorescent gold nanoclusters (PSP-Y-AuNCs) fabricated using a non-toxic natural polysaccharide (PSP001) demonstrated pH sensitive fluorescence emission pattern. The increased fluorescence readouts at acidic conditions and excellent biocompatibility made the PSP-Y-AuNCs an appealing candidate for in vivo tumor imaging applications.
