New Plasmonic Coating Technology Promises Rapid Sepsis Diagnosis

A research team at the Korea Institute of Materials Science (KIMS), led by senior researcher Minyoung Lee and principal researcher Sunggyu Park, has developed a label-free surface-enhanced Raman scattering (SERS) analysis technology. This innovative method directly grows plasmonic metal nanostructures on and around bacterial cells, enabling the rapid detection of extremely low concentrations of viable bacteria without conventional culture-based amplification. The technology, published in the journal *Small Methods*, can detect trace bacteria within one hour and assess their responses to antibiotics within two hours.

This development addresses a critical challenge in managing severe infectious diseases like sepsis, a life-threatening condition where the body's dysregulated response to infection leads to organ dysfunction. Rapid identification of the causative pathogen and timely administration of effective antibiotics are crucial for sepsis patients. However, conventional blood culture testing can take tens of hours or even several days to yield results, especially in the early stages of infection when bacterial concentrations in the bloodstream are extremely low. The KIMS team's new technology is expected to provide a foundation for much faster diagnosis and more precise antibiotic selection.

KIMS previously developed highly sensitive biosensor technologies utilizing three-dimensional plasmonic nanostructures to detect protein biomarkers associated with sepsis. The current research advances this by directly detecting the viable causative bacteria themselves and rapidly evaluating their response to antibiotics. The core of the new approach involves using bacterial cells as nucleation sites for the growth of plasmonic metal nanostructures. These nanostructures, formed directly on and around the bacterial cells, create highly localized electromagnetic enhancement, significantly amplifying the bacteria's intrinsic Raman signals.

SERS is an analytical technique that magnifies weak Raman signals characteristic of a material through intense electromagnetic fields, known as plasmonic hot spots, which form in nanoscale gaps between metallic nanostructures like gold or silver. Traditional SERS methods face a structural mismatch, as hot spots are typically only a few to tens of nanometers, while bacterial cells are about one micrometer, limiting contact. The KIMS team reversed this by forming plasmonic hot spots directly where bacteria are located, effectively amplifying signals without requiring separate labeling agents.

The technology was progressively developed through three stages: growing nanostructures around bacteria in solution, directly depositing metal nanostructures onto bacterial surfaces via electrochemical deposition, and finally integrating bacterial separation and enrichment with additional in situ nanostructure growth. This stepwise refinement substantially improved the ability to detect bacteria at extremely low concentrations. By combining the resulting SERS spectra with artificial intelligence-based analysis, the researchers were able to distinguish among eight different bacterial species.

The filtration-integrated SERS substrate successfully detected bacteria at concentrations as low as approximately 1–10 colony-forming units per milliliter (CFU/mL). The platform also demonstrated its potential for rapid antimicrobial susceptibility assessment by observing changes in SERS signal intensity correlating with bacterial viability. The team further confirmed the technology's performance in bacteria-spiked serum and urine samples and showed the ability to evaluate antibiotic response within two hours after exposing bacteria to antibiotics. The next step for the team involves conducting clinical validation in patient blood samples.

What to watch: Clinical validation of the technology in patient blood samples.

Editor's note: Exhaustive and precise reporting of the KIMS SERS technology, its mechanism, development stages, and performance metrics.