Development of an Enhanced Surface-Enhanced Raman Scattering (SERS) Plasmonic Sensor for the Detection of Klebsiella Pneumoniae Bacteria

Klebsiella pneumoniae, a gram-negative bacterium from the Enterobacteriaceae family, is a normal part of the human microbiota. It is present in about one-third of healthy individuals but can become an opportunistic pathogen, responsible for serious hospital-acquired infections like pneumonia, septicemia, urinary tract infections, and intra-abdominal infections. Rapid and accurate detection of K. pneumoniae is critical for controlling its spread. In this study, silver nanoparticles synthesized using the Tollens’ method were deposited on filter paper substrates to create a Surface-Enhanced Raman Scattering (SERS) biosensor. This SERS sensor detected K. pneumoniae at very low concentrations (as low as 101 CFU) by enhancing molecular vibrations due to electromagnetic effects of the nanoparticles. The sensor showed a detection enhancement factor of 7.942 × 10⁶, with a relative standard deviation (RSD) of 5.80% for six repeated measurements. The plasmonic SERS substrates demonstrated excellent recyclability, reproducibility, and stability, making them a promising tool for detecting K. pneumoniae in low numbers.