A label-free G-quadruplex DNA-based fluorescence method for highly sensitive, direct detection of cisplatin

• A novel fluorescence, convenient method was designed for detecting cisplatin.
• It shows high selectivity among tested drugs, even between platinum derivatives.
• This method can be applied to detect cisplatin in urine and image in living cells.
• Our test would not be interfered with by biological autofluorescence.

Cisplatin is a widely used anticancer chemotherapeutic, and fast, convenient detection methods for it are highly desirable. Based on the interaction of cisplatin with G-quadruplex DNA, we developed a simple label-free fluorescence method for rapid cisplatin detection. The titration experiment showed that the cisplatin concentration and the fluorescence signal change ratios (F0/F) exhibited a consistent linear correlation within the 1 to 10 μM range with a limit of detection of 720 nM, which was even lower than the common concentration of cisplatin in chemotherapy patients’ urine (54.3 to 321 μM). The equilibrium dissociation constant KD value for cisplatin binding was determined to be 1.19 × 10−5 M. This result demonstrated that our method had relatively high affinity toward cisplatin and could bind micromolar concentrations of cisplatin in solution. Our method also shows obvious selectivity among tested drugs, even between cisplatin and oxaliplatin/carboplatin. We demonstrated the high sensitivity of this methodology in the direct detection of cisplatin in urine samples and the fluorescence imaging of cisplatin in living cells.