Near-infrared light-driven polypyrrole/UiO-66-NH2 n-n heterojunction enabled paper-based photoelectrochemical aptasensing of bis (2-ethylhexyl) phthalate

In this paper, a near-infrared (NIR) light-activated polypyrrole (PPy)/UiO-66-NH2 n-n heterojunction enabled paper-based photoelectrochemical (PEC) aptasensing system integrated with exonuclease-III (Exo-III) assisted double-cycle amplification activated CRISPR/Cas12a strategy was established for sensitive determination of bis (2-ethylhexyl) phthalate (DEHP). This PPy/UiO-66-NH2 heterojunction with type II-scheme electron transfer pathway exhibited broad NIR light absorption and fast charge separation, producing a substantial initial photocurrent signal. Due to interruptive electron transfer caused by bulky biotin/streptavidin complexes, the photocurrent intensity was significantly decreased. When target existed, Exo-III assisted double-cycle amplification process activated the trans-cleavage ability of CRISPR/Cas12a, which cut biotin/streptavidin complexes from aptasensing interface and caused an increased photocurrent response. Consequently, the highly sensitive detection of DEHP was realized with good specificity, reproducibility, and practicality. This work provided an advanced PEC aptasensing platform for detecting DEHP in aqueous environment.