Flexible PDMS-SERS platform for culture-free diagnosis of bacterial infections in clinical wound care.

The early and accurate detection of pathogenic bacteria in infected wounds is crucial for preventing severe complications such as sepsis and multiple organ failure. This study presents a new surface-enhanced Raman scattering (SERS) platform based on polydimethylsiloxane (PDMS) flexible substrates and SERS probes for culture-free detection of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa). The PDMS flexible substrates, functionalized with gold nanoparticles (Au NPs) and specific antibodies, facilitate the efficient capture of bacteria and enhance the SERS signals through electromagnetic field coupling. The SERS probes, composed of Au@Ag core-shell nanoparticles with double-layer Raman reporter molecules, provide high sensitivity and specificity in bacterial detection. In the presence of target bacteria, the immunocomplex of PDMS flexible substrates, bacteria, and SERS probes forms, generating strong SERS signals and enabling sensitive bacterial detection. The SERS platform demonstrated limits of detection as low as 2.79 CFU/mL for E. coli, 3.42 CFU/mL for S. aureus, and 4.52 CFU/mL for P. aeruginosa. Additionally, the platform successfully monitored bacterial count changes in infected wound models and detected bacteria in clinical samples. These results indicate that the proposed SERS platform is a powerful tool for the rapid and sensitive detection of multiple bacteria in infected wounds, offering significant potential for clinical applications in infection management and advancing the field of bacterial diagnostics.