An ultrasensitive photoelectrochemical aptasensor based on ZnIn2S4/CdSe heterojunction for the detection of microcystine-LR
As an important heptapeptide toxin, microcystine-LR (MC-LR) has attracted extensive attention because of its great harm to animals, plants and plankton in water. Therefore, an ultrasensitive photoelectrochemical aptasensor based on ZnIn 2 S 4 /CdSe heterojunction was disigned to monitor MC-LR. In this strategy, the ZnIn 2 S 4 /CdSe heterojunction with matching energy levels was used as the substrate of the aptasensor. By reason of the effective separation of electrons and holes, the heterojunction exhibited wide light absorption region and increased light utilization rate, resulting in a higher electrical signal. The specific recognition of MC-LR depend on the precise binding with aptamer, which modified on the electrode through base complementary pairing. In the presence of MC-LR, MC-LR was specific recognized by MC-LR aptamer, the photocurrent signal amplifier Bi 2 S 3 was released from the aptasensor electrode, leading to a decreased photocurrent. The designed photoelectrochemical aptasensor showed an ultrasensitive detection for MC-LR with a wide response range from 10 -1 to 10 -8 µM, and lower detection limit of 0.55 × 10 -8 µM (3σ/S).
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