Sensitive DNA-based electrochemical strategy for trace bleomycin detection

Bleomycins (BLMs) are widely used in combination with chemotherapy for the treatment of a variety of cancers. The clinical application of BLMs is featured by the occurrence of sometimes fatal side effects, such as renal and lung toxicity, and the potential dose-limiting side effect of pulmonary fibrosis. Therefore, it is highly desirable to develop a sensitive method to quantitatively determine the BLM content in both pharmaceutical analysis and clinical samples, to make full use of therapeutic efficacy and to weaken its toxicity. Here, we proposed a simple, rapid, and convenient electrochemical assay for trace BLM detection. A reported DNA motif, as substrate for BLMs, is prepared to self-assemble onto the gold electrode to fabricate an electrochemical DNA (E-DNA) sensor, with a terminus tethered on the electrode surface and the other terminus labeled with ferrocenyl moiety as a signal reporter to form a stem-loop structure, giving an arise of remarkable faradaic current. In the presence of Fe(II)·BLM, the E-DNA sensor undergoes the irreversible cleavage event, which can be transduced into a significant decrease in current peak. This proposed sensor reveals an impressive sensitivity as low as 100 pM BLMs and exhibits a good performance as well as in serum sample. Considering the high sensitivity and specificity of this proposed sensor, as well as the cost-effective and simple-to-implement features of the electrochemical technique, we believe that this method shows distinct advantages over conventional methods and it is a promising alternative for the determination of trace amounts of BLMs in clinical samples.