Microporous membrane-based polymer gating biosensor for the detection of Staphylococcus aureus and antimicrobial...

Rapid and accessible detection of pathogenic bacteria and testing of antimicrobial susceptibility are crucial for environmental risk management and pollution control, yet conventional methods are often laborious and time-consuming. In this work, we develop a simple but versatile microporous membrane-based polymer gating (MPG) biosensor with flow time-based readout, using gelatin as gelatinase-responsive polyme to demonstrate Staphylococcus aureus (S. aureus) detection and antimicrobial susceptibility testing. A home-built portable negative pressure pumping system was employed to automatically drive the flow of gelatin solution through a microporous membrane. With the solution passing through, gelatin molecules gradually accumulate and partially block the membrane. Consequently, it impedes the flow speed and results in an increased flow time needed for the solution to reach the detection line, which varies with the concentration of gelatin solution. As S. aureus can secrete gelatinase that hydrolyzes gelatin, it obviously reduces membrane blockage and significantly decreases the flow time. Notably, this method achieves quantitative detection of S. aureus at concentrations as low as 1 CFU/mL and performs reliably in actual samples including human urine, orange juice, and lake water. Furthermore, by measuring the flow time of S. aureus solutions with different antibiotics, the precise determination of bacterial susceptibility to antibiotics can be achieved successfully. Overall, the MPG biosensor offers advantages in simplicity, cost-effectiveness, user-friendliness, and remarkable sensitivity, which addresses major limitations of traditional gelatin liquefaction test and broth microdilution method, thereby opening a new avenue for pathogenic bacterial detection and antimicrobial susceptibility testing.