A separated type cathode photoelectrochemical aptasensor for thrombin detection based on novel organic polymer heterojunction photoelectric material

Abstract

In this work, poly(5-formylindole)/poly(3,4-ethylenedioxythiophene) (P5FIn/PEDOT) organic polymer heterojunction was firstly prepared and utilized as a novel photocathode material to construct a separated type cathode photoelectrochemical (STC-PEC) aptasensor for ultrasensitive and selective detection of thrombin (TB). Specifically, P5FIn/PEDOT heterojunction and TB aptamers in this PEC sensor were modified on different ITO electrodes to make the photoexcitation and biological recognition process separately. P5FIn/PEDOT heterojunction was prepared by simple two-step electrochemical polymerization and exhibited a strong photocurrent signal owing to the synergistic effect between P5FIn and PEDOT. This photocathode need not to be replaced in the PEC measurement improving the reproducibility. This construction strategy of the proposed sensor avoided the mutual interference between photoexcitation process and biological detection process, and effectively improved the sensitivity, reproducibility and stability of this PEC sensor. The proposed STC-PEC aptasensor had a detection range of 0.000100 nM–10.0 nM with a detection limit of 0.0410 pM, also showing an excellent applicability in the detection of TB in real human serum samples. This STC-PEC aptasensor not only has a good potential application in future clinical medical diagnosis and disease treatment but also provides new ideas for the development of PEC sensors.