A nano-silver modified heterojunction of bismuth sulfide nanoflowers–titania nanorods for sensitively detecting alpha-fetoprotein

Abstract

Developing rapid and sensitive photoelectrochemical (PEC) platforms for detecting alpha-fetoprotein (AFP) is of utmost importance. A PEC aptasensor system was constructed in this investigation to specifically detect AFP. The visible light-active materials employed in this system include nano-Ag/bismuth sulfide (Bi₂S₃)/TiO₂ nanorod arrays (NRAs), while the recognition element used is the AFP aptamer. The created p–n heterojunction by loading Bi₂S₃ on TiO₂ NRAs facilitated efficient separation of electron–hole pairs. Finally, the integration of nano-Ag onto the Bi₂S₃/TiO₂ NRA heterojunction induced surface plasmon resonance (SPR), leading to an intriguing Z-scheme mechanism that expanded the spectrum of light absorption and enhanced electron transfer efficiency. This resulted in an expanded visible light absorption range, improving the photoresponsivity of the PEC sensor. In the concentration range of 0.002 ng mL⁻¹ to 100 ng mL⁻¹, the platform exhibited excellent selectivity and successfully detected concentrations as low as 5.1 pg mL⁻¹ (S/N = 3). With its distinctive design, this sensor demonstrates the ability to identify AFP in human serum.