Gold nanorod-mediated multicolor biosensor for visual detection of Streptococcus agalactiae during pregnancy in actual clinical samples

Background Streptococcus agalactiae ( S. agalactiae ) has attracted much attention due to its potential threat to the health of mothers and infants. Especially during the perinatal period, its infection may lead to a series of serious complications, thus conducting tests for S. agalactiae serves as a highly effective preventive measure during pregnancy. Currently, available S. agalactiae detection methods used in clinical trials suffer from several notable limitations. These include prolonged testing durations, the necessity for sophisticated and costly equipment, and an inability to provide real-time visualization of test results. Results In this study, we successfully devised multicolor visualization assay using gold nanorods (GNRs) as mediators for a simple, rapid, sensitive, and reliable of S. agalactiae detection. This method innovatively utilizes recombinase polymerase amplification (RPA) to efficiently amplify cfb gene, while employing streptavidin-modified magnetic beads (MBs-SA) for rapid separation of amplification products. This approach substantially shortens reaction time, allowing entire detection process to be completed within 30 min. The localized surface plasmon resonance (LSPR) of GNRs enable multicolor changes in results and naked-eye identification, eliminating the reliance on expensive detection instruments, while achieving an impressive sensitivity of 1 copy/μL. Significance The proposed method demonstrates satisfactory accuracy and specificity, requires no complex instrumentation, and enables visual detection of results. It holds significant potential and value for application in resource-limited settings such as home care facilities, and primary hospitals for preventing S. agalactiae infection.