KCS

Rapid and sensitive identification of pathogenic bacteria is a key factor for the early diagnosis of infectious disease. Serological culturing-based assays are extensively used for the identification of bacteria but it takes a long time due to their culturing process. Polymerase chain reaction (PCR) is another analytical tool for detecting bacteria. However, PCR also needs an amplification of target genes using thermo-cycling steps because the concentration of target gene sequence is relatively lower than that of unrelated gene sequences. In many cases, amplification process causes false-positive signals and wrong identification. To resolve these problems, we developed a novel amplification-free SERS imaging sensor for the rapid and sensitive detection of Salmonella typhimurium bacteria. This technique does not require any cell culture or DNA amplification processes due to its highly sensitive detection capability. For this purpose, we fabricated antibody-conjugated SERS nano tags and three-dimensional nanopillar-pattered SERS substrates. The analytical strategy involves 3 steps; (1) immobilization of capture antibodies on nano-pillar substrate, (2) capturing of bacteria using specific interaction between antibodies and bacteria, and (3) labelling of bacteria with SERS nano tags and their SERS imaging detection. This SERS-based imaging sensor allows the limit of detection (LOD) of Salmonella typhimurium bacteria as low as 4,000 CFU/mL without any sample enrichment process. This SERS-based imaging technique is expected to be a potentially useful tool for the rapid and sensitive detection of pathogenic bacteria.