A portable photoelectrochemical aptasensor based on voltage-resolved dual-signal output for the determination of chloramphenicol.

Developing a ratiometric photoelectrochemical (PEC) aptasensor that can produce cathode-anode dual photocurrent signals is still a great challenge. Herein, we report a novel portable voltage-resolved ratiometric PEC aptasensor for the determination of chloramphenicol (CAP) with a digital multimeter (DMM) and voltage and current signal generator (VCSG) readout. Ru(bpy)32 +-BiOBr heterojunction was employed as the only photoactive material, which is switched between type II and Z - scheme by varying the bias voltage (+0.1/-0.2 V). With the increase of CAP concentration, the PEC signal of type II (I+0.1) is positive and decreases at + 0.1 V, while the PEC signal of Z - scheme (I-0.2) is negative and increases at -0.2 V. Due to the selectivity of aptamer method and sensitivity of ratiometric method (I-0.2/I+0.1), the as-prepared aptasensor for detecting CAP exhibits an excellent linear detection range from 5.0 × 10-12 to 1.0 × 10-7 M with a limit of detection of 1.2 × 10-12 M. In addition, this portable aptasensor was used to detect CAP in real samples with satisfactory results, revealing a promising avenue for the on-site analysis and food safety.