ABSTRACT
Cytokine storms are known as the uncontrolled overproduction of inflammatory cytokines that can be produced by a variety of viral or non-infectious disorders and inflict significant damage to many organs. Interleukin-10 (IL-10) is an anti-inflammatory cytokine, and rapid detection of its levels in serum and saliva is important for many diseases, including severe COVID-19 patients. In this study, Polystyrene (PS) fibers were electrospun over a gold electrode and modified by air plasma to allow their further decoration with polyamidoamine (PAMAM) dendritic polymer for providing many active sites on the fiber surface. The fabricated three-dimensional (3-D) architecture was employed as a platform in an impedimetric immunosensor for the quantitative detection of interleukin-10 cytokine (AgIL-10). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, fluorescence microscopy, UV–vis spectroscopy, and electrochemical methods including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterized the proposed electrospun fiber-based platform and electrochemical immunosensor. The PAMAM properties increased not only the amperometric response to the ferro/ferri cyanide redox probe, of the modified gold electrode but also the active surface area available for covalently binding of anti-IL-10 capture antibody, resulting in the sensitive detection of AgIL-10 in the concentration range of (1-50 pg/mL) in phosphate buffer saline (PBS) with a limit of detection (LOD) of 1 pg/mL. The immunosensor's performance in detecting AgIL-10 in artificial saliva (AS) as a complex medium was likewise satisfactory. This immunosensor provides a new opportunity for clinical immunoassays thanks to its great sensitivity,selectivity, andstability.
ABSTRACT
The projection of new biosensing technologies for genetic identification of SARS-COV-2 is essential in the face of a pandemic scenario. For this reason, the current research aims to develop a label-free flexible biodevice applicable to COVID-19. A nanostructured platform made of polypyrrole (PPy) and gold nanoparticles (GNP) was designed for interfacing the electrochemical signal in miniaturized electrodes of tin-doped indium oxide (ITO). Oligonucleotide primer was chemically immobilized on the flexible transducers for the biorecognition of the nucleocapsid protein (N) gene. Methodological protocols based on cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and atomic force microscopy (AFM) were used to characterize the nanotechnological apparatus. The biosensor's electrochemical performance was evaluated using the SARS-CoV-2 genome and biological samples of cDNA from patients infected with retrovirus at various disease stages. It is inferred that the analytical tool was able to distinguish the expression of SARS-CoV-2 in patients diagnosed with COVID-19 in the early, intermediate and late stages. The biosensor exhibited high selectivity by not recognizing the biological target in samples from patients not infected with SARS-CoV-2. The proposed sensor obtained a linear response range estimated from 800 to 4000 copies µL-1 with a regression coefficient of 0.99, and a detection limit of 258.01 copies µL-1. Therefore, the electrochemical biosensor based on flexible electrode technology represents a promising trend for sensitive molecular analysis of etiologic agent with fast and simple operationalization. In addition to early genetic diagnosis, the biomolecular assay may help to monitor the progression of COVID-19 infection in a novel manner.