Sensitive Methicillin-Resistant Staphylococcus Aureus (MRSA) DetectionUsing Gold Nanoparticle-Based Satellite Network With Potential For EarlyDiagnosis of Diabetes-Related Infection

Background: As pathogenic bacteria account for the leading cause of diabetes-related infections, sensitive detection of bacteria from clinical samples has attracted abundant attention. Methods: We propose an innovative DNA-AuNP-based sensing system that integrates low-speed centrifugal bacteria isolation, detection and protein analysis. In the method, RCA (rolling circle amplification) is utilized to produce a long-ssDNA (single-strand DNA), which can form a hairpin structure comprising repeats of functional domains, such as PBP2a aptamer. When aptamers bind to target bacteria, the hairpin structure in the RCA product changes its conformation, exposing the AuNP binding sequence. As a result, the probe on the surface of AuNP hybridizes with AuNP binding sequence in RCA product by strand displacement reaction, releasing the fluorescent-labeled complementary probe as the detection signal. The simultaneous formation of the bacteria-DNAAuNP satellite network enables the isolation of target bacteria by low-speed centrifugation. Results: Eventually, we applied the method for MRSA (methicillin-resistant Staphylococcus aureus) detection and obtained a favorable detection performance with a limit of detection of 275 cfu/μL. Conclusion: We believe the method has potential application in the early diagnosis of diabetesrelated infections.