Dual-ratiometric aptasensor for streptomycin detection based on the in-situ coupling of photoelectrochemical and electrochemical assay with a bifunctional probe of methylene blue

This work reports a dual-ratiometric aptasensor based on the in-situ coupling of photoelectrochemical (PEC) and electrochemical (EC) assay for streptomycin (STR) detection. The key point is to take advantage of methylene blue (MB) as a bifunctional probe to simultaneously produce photocurrent (IMB-PEC) and redox current (IMB-EC).MB serves as a bridge to couple PEC with EC assay in situ, offering a PEC&EC dual-mode sensing. The redox current of fermcene (IFc-EC) is designed as reference signal. Based on this principle, the specific recognition of STR leads to the stripping of Fc-tagged aptamer, and triggers the hybridization chain reaction to construct DNA duplex capable of absorbing MB. Using IMB-EC/I(Fc-EC )and IMB-PEC/IFc-EC as yardsticks, the aptasensor offers two sets of linear ranges, i.e., 1 x 10(-11)-1 x 10(-5) M for IMB-EC/IFc-EC and 1 x 10(-9)-1 x 10(-4) M for IMB-PEC/IFc-EC. The dual-ratiometric strategy endows the aptasensor with enhanced analytical performances compared with that of single-signal or single-ratiometric assay. Our work offers an efficient way to fabricate high-performance aptasensors, and MB-based dual-mode sensing may provide a right tool to study interactions between PEC and EC behaviors.

Automated summary

This work presents a dual-ratiometric aptasensor for streptomycin detection, utilizing the in-situ coupling of photoelectrochemical and electrochemical assays. The use of methylene blue as a bifunctional probe enables the simultaneous generation of photocurrent and redox current, resulting in enhanced analytical performances compared to single-signal or single-ratiometric assays. The MB-based dual-mode sensing offers a promising tool for studying interactions between PEC and EC behaviors.