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Published on: July 22, 2013
DNA nanoreactor-programmed interface modulation of Schottky junctions via etching for ultrasensitive dual-modal
Haoyu Zhang1, Min Zhao1, Huijie Wang1
1College of Chemistry and Chemical Engineering, Shandong Provincial Key Laboratory of Intelligent Molecular Science and Engineering, Qingdao Key Laboratory of Intelligent Molecular Manufacturing and Precise Health, Qingdao University, Qingdao, 266071, PR China.
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The sensitivity and accuracy of photoelectrochemical (PEC) biosensors are often constrained by high electron-hole recombination rates and reliance on a single detection mode. To address this limitation, an ultrasensitive PEC-colorimetric (CM) dual-mode biosensor has been designed based on DNA nanoreactor-programmed modulation of protonated g-C3N4/AuNPs (PCN/AuNPs) Schottky junctions via a target-triggered etching effect. The Schottky junction formed between AuNPs and PCN through electrostatic interactions effectively modulates the energy band structure, thereby enhancing electron-hole separation. Furthermore, the localized surface plasmon resonance (LSPR) effect of AuNPs broadens the light absorption range, enables a highly localized and intensified electromagnetic field, which promotes rapid interfacial charge transfer. Taking carcinoembryonic antigen (CEA) as a model target, a DNA nanoflower-based cascade nanoreactor integrated with glucose oxidase and horseradish peroxidase (DFs@GOx/HRP) is constructed via rolling circle amplification (RCA) with target-specific aptamer programming. Upon recognition of CEA, a sandwich-type composite forms, initiating a cascade catalytic reaction of the nanoreactor using glucose as the substrate to generate oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB), thereby enabling CM detection. In the PEC detection mode, the generated oxTMB under acidic conditions further oxidizes to TMB2+, which etches the AuNPs on the PCN/AuNPs surface, further breaks the Schottky junctions and weakens electrical conductivity, resulting in a decrease in photocurrent. This dual-mode biosensor achieves remarkable detection limits of 16.8 pg mL-1 for PEC and 0.46 ng mL-1 for CM detection along with high specificity. The proposed programmable strategy establishes a universal platform for dual-mode biosensing, facilitating complementary information acquisition from distinct transducers for more comprehensive analytical applications.
