Ratiometric Fluorescence/Colorimetry/Smartphone Triple-Mode Real-Time Detection of Doxorubicin by Nitrogen-Doped Carbon Dots

Doxorubicin (DOX) is used as a chemotherapeutic drug to treat cancer; however, it has many side effects. So, the detection of DOX is essential for its regulation and controlled usage in biological systems. Herein, a ratiometric fluorescence/colorimetry/smartphone was employed for the detection of DOX using nitrogen-doped carbon dots (N-CDs). The N-CDs were synthesized using low-cost precursors (ascorbic acid and urea) via a simple hydrothermal method. The as-prepared N-CDs help to detect DOX within a minute (0.5 min) with high sensitivity and selectivity and facilitate its visual detection by the naked eye. The limits of detection for the fluorimetric and colorimetric methods were 0.058 and 0.70 μM, respectively. The N-CDs can also detect DOX in human biofluids (blood serum) in fluorimetry and colorimetry, with recovery percentages of 97.39–105.36% and 96.21–104.99%, respectively.