Image created by Dr. Michael J. Miller
An analytical technology has been developed that can detect ultra-trace amounts of bacteria within one hour, helping enable rapid response to severe infectious diseases such as sepsis. Because the technology can also assess how bacteria respond to antibiotics within two hours, it is expected to support more precise prescription of drugs.
The Korea Institute of Materials Science (KIMS) announced on the 9th that a research team led by Senior Researcher Minyoung Lee and Principal Researcher Sungkyu Park of the Bio-Health Materials Research Division has developed a label-free surface-enhanced Raman scattering (SERS) analytical technology that rapidly detects ultra-low concentrations of live bacteria. The research results were published in the August 16 issue of the international journal 'Small Methods'.
Viruses that invade the body multiply exponentially and can adversely affect the entire body within a few hours. It is crucial to quickly identify the causative pathogen and administer antibiotics. However, in the early stages of infection, the amount of bacteria in the blood is so low that it is difficult to directly detect them.
Currently, bacteria are detected by collecting blood samples and then culturing the bacteria present in them. This approach has the limitation that it takes tens of hours to several days to determine the causative pathogen and identify the appropriate antibiotic.
Molecules that make up bacteria emit a 'Raman signal' when they interact with externally applied light. Raman signals appear differently depending on the type of bacteria.
The research team designed a 'plasmonic metal nanostructure' with the ability to amplify Raman signals so that it spontaneously grows while enveloping the surface and surroundings of bacteria. In practice, they flowed an electric current through a solution containing both bacteria and metal nanomaterials, effectively 'plating' the bacteria with the metal nanomaterials.
The team implemented on a single substrate all the functions of plating the bacteria, filtering and concentrating the plated bacteria in one place, and detecting the Raman signals emitted from the concentrated bacteria. As a result, they were able to detect even very small bacterial loads of 1–10 CFU (colony-forming units; 1 CFU corresponds to one bacterium capable of forming a colony) per 1 mL within one hour.
They also verified the detection performance using simulated samples in which live bacteria were added to serum and urine.
The researchers noted that by treating live bacteria with antibiotics and then reading changes in the Raman signals, it is possible to evaluate bacterial responses to antibiotics within two hours.
Senior Researcher Lee said, “The key to this study is that we overcame the limits of detecting ultra-trace bacteria by growing nanostructures directly where the bacteria are,” adding, “In the future, we aim to contribute to faster treatment decisions for sepsis by rapidly detecting the causative pathogen in the blood of actual infected patients and assessing antibiotic responses.”
Reference
E.-B. Jang, J. Y. Lee, H. Chung, and M.-Y. Lee, Filtration-Based SERS With In Situ Gold Growth in Bacterial Microenvironment for Rapid Detection of Low-Level Bacteria. Small Methods (2026): e70972. https://doi.org/10.1002/smtd.70972
Abstract
Rapid bacterial detection and timely antimicrobial susceptibility assessment are essential for effective infection management, yet remain challenging under clinically relevant low-concentration conditions. Here, we present a filtration-based surface-enhanced Raman scattering (SERS) platform based on a microenvironment engineering strategy, in which plasmonic nanostructures are dynamically formed within the bacterial microenvironment. Using a gold nanostructured glass microfiber membrane, the platform enables large-volume sample processing through size-selective bacterial capture, followed by in situ gold growth that generates bacteria-centered plasmonic hotspots directly around bacterial cells. This architecture fundamentally overcomes the intrinsic hotspot–bacteria mismatch in conventional substrate-based SERS systems, enabling highly sensitive and selective detection while effectively suppressing nonspecific interference in complex biological matrices. To further address sampling limitations at low concentrations, a minimal pre-culture strategy was introduced to enhance bacterial surface occupancy, improving the detection limit from 103 to 101 CFU/mL. In addition, SERS signal intensity directly reflects bacterial viability, allowing rapid differentiation of antimicrobial responses and enabling susceptibility assessment within 2 h. By integrating physical enrichment with microenvironment-driven signal amplification, this platform simultaneously achieves low-level detection and rapid antimicrobial susceptibility testing within a single system. These results highlight its potential as a next-generation integrated diagnostic platform for clinical sample analysis.