Ratiomeric Luminescent Monitoring of Cardiovascular Agents Exploiting Phosphorus and Nitrogen Co‐Doped Carbon Quantum Dots as Nano‐Sensors: Bioavailability Study in Rabbit Males

Phosphorus and nitrogen co-doped carbon quantum dots (PNCQDs) were utilized as facile fluorescent probes for accurate monitoring of naftidrofuryl oxalate (NAFT) and rivaroxaban (RIVA). These luminescent templates have shown two emission ratiomeric bands at 335 and 444 nm upon excitation at 273 nm. Successive titration of the carbon dots with NAFT solution showed enhanced fluorescence at 335 nm band, leaving the other band unchanged, while by consecutive addition of RIVA increments to the PNCQDs-NAFT complex, a fluorescence quenching occurred only to the same band. All measurements were performed in phosphate buffer; pH 7.40 ( 3.00 × 10^-3 M) for ≈ 2 min reaction time. The method was validated according to the International Conference on Harmonization (ICH) guidelines with percentage relative standard deviation values (%RSD) not more than 2.90%. The studied analytes have shown excellent sensitivity with limits of quantitation (LOQ) of 1.50 × 10^-3 and 3.00 × 10^-3 μg/mL for NAFT and RIVA, respectively, as well as outstanding selectivity towards a wide range of interfering species. Recovery percentages of 97.00-98.00 were obtained upon application to tablets and spiked plasma samples. The developed method was successfully employed in estimating the pharmacokinetics of both analytes in male rabbits.