A DNA-programmed magnetic photoactive probe enabling discriminative photoelectrochemical sensing of diverse targets

The integration of magnetic nanomaterials and photoelectrochemical aptamer sensing strategies offers significant potential for rapid separation of target molecules, improved detection sensitivity and enhanced accuracy. However, the limited photoelectrochemical activity of magnetic nanomaterials and the high cost of aptamer sensors hinder their advancement. This study innovatively realized the independent, sensitive, and precise photoelectrochemical detection of different target molecules on same platform by constructing ultra-efficient magnetic photoactive probe, ZnFe₂O₄/Bi₂O₂S/AuNPs/C1-C2. The designed ZnFe₂O₄/Bi₂O₂S/AuNPs exhibited high photocurrent response activity, efficient magnetic separation performance, and high aptamer immobilization capacity. Additionally, the elaborately designed DNA duplex C1-C2 probe also served dual functions, acting as "aptamer" for target identification and "bridging linker" to connect ZBA or capture hemin for different target detection, thereby inducing photocurrent polarity reversal or photocurrent enhancement. These two targets share the core recognition component, the same electrode interface, and testing conditions, yet generate photocurrent signals with opposite polarity, enabling the determination of various targets on the same sensing platform and significantly improving sensing efficiency. The sensor achieved a low detection limit for chloramphenicol (24.6 pM) and ampicillin (14.5 fM), and demonstrated high precision with relative standard deviations of 4.5 % for chloramphenicol detection and 2.0 % for ampicillin detection. Furthermore, this strategy maximizes the advantages of DNA and nanomaterials, simplifies operation procedures and opens new avenues for developing low-cost, highly reliable multi-target detection technologies.