The synergy of Fe3O4@Au and molybdate as HRP-mimetic catalysts for gold nanorods etching: Development of an ultrasensitive genosensor for detection of Helicobacter pylori

• Published in: Sensors and actuators. B, Chemical Chemical, 2022-11, Vol.371, p.132600, Article 132600
• Main Authors: Kermanshahian, Kimia, Yadegar, Abbas, Moghimi, Hamid, Ghourchian, Hedayatollah
• Format: Article
• Language: English
• Subjects: Biomarkers; Biosensor; Etching; Glucose oxidase; Gold; Gold nanorods; Helicobacter pylori; HRP-mimetic; Hydrogen peroxide; Iodine; Iron oxides; Localized surface plasmon resonance; Nanoparticles; Nanorods; Optical properties; Oxidation; Peroxidase; Plasmonics; Polymerase chain reaction
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2022.132600

Etching changes the optical properties of plasmonic nanoparticles by oxidizing their atoms. In iodine-mediated gold nanorods (AuNRs) etching, H2O2 oxidizes I– to I3–, which turns Au0 to Au+. In this work, the ability of Fe3O4@Au nanoparticles for iodide oxidation was proved. Also, the synergy between peroxidase-mimic Fe3O4@Au nanoparticles and molybdate ions on iodide oxidation was utilized to enhance the etching rate and design a rapid, cost-effective, and ultrasensitive genosensor for the detection of Helicobacter pylori (H. pylori). In the presence of glmM fragment as a conserved H. pylori biomarker, DNA sandwiches consisting of capture probe-conjugated Fe3O4@Au nanoparticles, target sequence, and glucose oxidase (GOx)-labeled reporter probe were formed. After separating the GOx-labeled DNA sandwiches carried on Fe3O4@Au nanoparticles using an external magnet, the required substances for etching were added. Eventually, the GOx-generated H2O2 initiates the Fe3O4@Au- and molybdate-catalyzed iodine-mediated AuNRs etching. The blue shift of AuNRs’ longitudinal plasmonic peak was detected by a spectrophotometer. Under the optimal condition, an excellent sensitivity toward H. pylori was obtained with a linear range and detection limit of 40–2040 aM and 31.8 aM, respectively. Also, the fabricated genosensor showed satisfactory feasibility against real biopsy samples, validated by polymerase chain reaction (PCR) and bacterial culture. [Display omitted] •A gold nanorod etching-based genosensor was fabricated for Helicobacter pylori.•The genosensor is novel, specific, cost-effective, user-friendly, and ultrasensitive.•The synergistic catalytic activity of Fe3O4@Au nanoparticles and molybdate on iodide oxidation was proved.•The detection limit and linear range were measured at 31.8 aM and 40–2040 aM, respectively.