Ultra-sensitive magnetic nanomechanical array sensor based on graphene oxide for single bacterial cell detection

Pathogenic bacterial infections pose major health threats and economic burdens. Rapid and highly sensitive biochemical sensors are essential for bacterial detection in food safety and clinical applications. Here, we introduce a graphene oxide (GO)-based magnetic nanomechanical array sensor that utilizes the large surface area of GO to bind more magnetic nanoparticles (MNPs) and aptamers. Rapid and ultra-sensitive detection can be achieved even at extremely low target concentrations. This approach can directly detect a single Escherichia coli cell without time-consuming bacterial culture, and the linear detection range is 1–100 CFU·mL⁻¹. Meanwhile, the sensor showed good specificity, reproducibility, stability, and stance to interference, and could detect 1 CFU·mL⁻¹ Escherichia coli in milk. Moreover, we realized the simultaneous detection of two bacteria at extremely low concentrations, which proved that the sensor had the potential for high-throughput detection. In addition, for extremely low-concentration samples (< 100 CFU·mL⁻¹), we controlled the magnetic force at the tip of the microcantilever, greatly enhancing its deflection and sensitivity. This method provides a novel and ultrasensitive method for the timely detection of pathogenic bacteria, and can also be applied to the highly sensitive detection of other targets such as DNA, small molecules, proteins, and viruses by using different probes. Our research provides a promising tool for effective, rapid and highly sensitive detection in the field of public health and food safety.