Palindromic Molecular Beacon Based Z‑Scheme BiOCl-Au-CdS Photoelectrochemical Biodetection

• Published in: Analytical chemistry (Washington) Vol. 91; no. 3; pp. 2447 - 2454
• Main Authors: Zeng, Ruijin, Luo, Zhongbin, Su, Lingshan, Zhang, Lijia, Tang, Dianping, Niessner, Reinhard, Knopp, Dietmar
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05.02.2019
• Subjects: Aptamers; Biosensors; Bismuth; Cadmium sulfide; Chemistry; Deoxyribonucleic acid; DNA; Electron transfer; Fragmentation; Fragments; Gold; Hybridization; Kanamycin; Molecular machines; Nanoparticles; Nicking endonuclease; Photoelectric effect; Photoelectric emission; Polymerization; Quantum dots; Substrates; Synergistic effect
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.8b05265

This work presented an innovative and rationally engineered palindromic molecular beacon (PMB) based “Z-scheme” photoelectrochemical (PEC) biosensing protocol for the selective screening of kanamycin (Kana) through DNA hybridization-induced conformational conversion. Interestingly, the ingeniously designed PMB integrated the multifunctional elements including recognition region, primer-like palindromic fragment, and polymerization-nicking template. The cosensitized structures consisted of CdS quantum dot functionalized hairpin DNA2 (QD-HP2) and region-selectively deposited gold nanoparticles onto {001} facets of bismuth oxychloride (BiOCl-Au). Compared with BiOCl-Au alone, the attachment of CdS QDs onto BiOCl-Au (i.e., BiOCl-Au-CdS QDs) exhibited evidently enhanced photocurrent intensity thanks to the synergistic effect of Z-scheme BiOCl-Au-CdS QDs. After incubation with target Kana, Kana–aptamer binding could induce the exposure of PMB region for hairpin DNA1 (HP1). The exposed palindromic tails hybridized with each other (like a molecular machine) to consume the substrates (dNTPs) and fuels (enzyme) for the releasing of numerous nick fragments (Nick). The as-generated nick fragments could specifically hybridize with the complementary region of QD-HP2, thus resulting in decreasing photocurrent because of the increasing spatial distance for electron transfer between two-type photosensitizers. Under optimum conditions, the PMB-based sensing system exhibited satisfying photocurrent responses toward target Kana within the working range from 50 to 5000 fM at a low detection limit of 29 fM. Impressively, the concept of a palindromic fragment-mediated primer-free biosensing strategy offers a new avenue for advanced development of efficient and convenient biodetection systems.