Copper single-atom-based flexible aptamer biochip for simultaneous monitoring of bladder cancer-related bacteria

R apid and accurate detection of pathogenic bacteria is crucial for disease diagnosis in clinical practice. The infection of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) is closely related to the development and complications of patients with bladder cancer. In this study, an aptamer biochip for E. coli and S. aureus simultaneous detection was developed based on copper single atom material (Cu-SAC) and gold nanoparticles (AuNPs) via high-resolution electrohydrodynamic (EHD) printing technology. The main strategy was based on the specific recognition of aptamer and the signal amplification of AuNPs/Cu-SAC. Following aptamer immobilization, the electrochemical signal gradually decreased. Using this proposed electrochemical aptamer biochip, E. coli and S. aureus can be quantified at a linearity range of 10-1.0 × 10⁸ CFU mL^-1. The limit of detection (LOD) was as low as 3 CFU mL⁻¹. The outstanding signal amplification performance is due to the combination of Cu-SAC and AuNPs, which efficiently supply electrons to Fe³⁺, thereby facilitating the Fe³⁺/Fe²⁺ cycle. Furthermore, employing this portable biochip enables simultaneous measurements of E. coli and S. aureus concentrations in urine and milk samples with acceptable recoveries. This portable biochip holds significant potential for pathogenic bacteria detection  in field-based applications. Moreover, it is expected to provide a powerful auxiliary means for the monitoring  of bladder cancer patients.