Graphical abstract

Following the sudden widespread of the novel coronavirus (COVID-19) which first appeared in Wuhan city. Remdesivir (REM) was the first medicine licensed by the US Food and Drug Administration (FDA) for COVID-19 infected hospitalized patients.Hence, there was an urgent demand for the optimization of efficient selective and sensitive methods to be developed for the determination of REM in pharmaceuticals as well as biological samples. A sensitive and simple green spectrofluorimetric

No abstract

Ribavirin (RIB) was successfully determined by fluorescence spectroscopy upon its quenching to environment friendly phosphorus and nitrogen co-doped carbon quantum dots (PNQDs). Different analytical parameters affecting the fluorescence spectra have been optimized and validated in accordance to the ICH guidelines. The proposed method has provided an efficient tracing of the interaction between RIB molecules and the synthesized QDs in an acidic medium (off-mode). The RIB molecules have shown excellent sensitivity by quenching of the emission band at 401 nm upon excitation at 245 nm throughout a linear range of 0.06–10.00 µg/mL with detection and quantitation limits down to 14.00 and 40.00 ng/mL, respectively. The quenching mode was proven to be static in raw samples and samples extracted of spiked plasma for quenching rate constants of 1.30 × 1012 L M−1 S−1 and 1.73 × 1012 L M−1 S−1, respectively. The proposed method has been successfully applied for determination of RIB in the commercial capsules and spiked human plasma samples with good recovery percentages in between 102.00 and 103.00%. Interestingly, these carbon dots have been utilized as nano-fluorescent platforms for assessment of the binding interaction kinetics between the RIB molecules and salmon sperm DNA (ssDNA). This has been implemented through peeling off the RIB molecules from surface of the PNQDs upon successive addition of the ssDNA and hence fluorescence restoration (turning on). Consequently, this provides  a successful monitoring of its antimicrobial potency. It was evidenced a strong binding interaction with a binding constant of 2.38 × 104 mol−1/L. Significantly, this could open doors for an extended application for on-site monitoring of RIB as well as its interactions with biomolecules and microorganisms.