Titanium dioxide–mediated resistive nanobiosensor for E. coli O157:H7

A titanium dioxide nanoparticle (TiO₂ NP)–mediated resistive biosensor is described for the determination of DNA fragments of Escherichia coli O157:H7 (E. coli O157:H7). The sol-gel method was used to synthesize the TiO₂ NP, and microlithography was applied to fabricate the interdigitated sensor electrodes. Conventional E. coli DNA detections are facing difficulties in long-preparation-and-detection-time (more than 3 days). Hence, electronic biosensor was introduced by measuring the current-voltage (I–V) DNA probe without amplification of DNA fragments. The detection scheme is based on the interaction between the electron flow on the sensor and the introduction of negative charges from DNA probe and target DNA. The biosensor has a sensitivity of 1.67 × 10¹³ Ω/M and a wide analytical range. The limit detection is down to 1 × 10⁻¹¹ M of DNA. The sensor possesses outstanding repeatability and reproducibility and is cabable to detect DNA within 15 min in a minute-volume sample (1 μL).