Development of a Magnetically-Assisted SERS Biosensor for Rapid Bacterial Detection

Abstract

Siyun Cheng,1,2,* Zhijie Tu,2,* Shuai Zheng,3 Adeel Khan,4 Ping Yang,1 Han Shen,1 Bing Gu2,3 1Department of Clinical Laboratory, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, People’s Republic of China; 2Medical Technology School of Xuzhou Medical University, Xuzhou, People’s Republic of China; 3Department of Clinical Laboratory Medicine, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, People’s Republic of China; 4Department of Biotechnology, University of Science and Technology, Bannu, KP, Pakistan*These authors contributed equally to this workCorrespondence: Han Shen, Department of Clinical Laboratory, Nanjing Drum Tower Hospital, Nanjing, People’s Republic of China, Tel [phone], Fax [phone], Email [email protected] Bing Gu, Department of Clinical Laboratory Medicine, Guangdong Provincial People’s Hospital, Guangzhou, People’s Republic of China, Tel [phone], Fax [phone], Email [email protected]: Ultrasensitive bacterial detection methods are crucial to ensuring accurate diagnosis and effective clinical monitoring, given the significant threat bacterial infections pose to human health. The aim of this study is to develop a biosensor with capabilities for broad-spectrum bacterial detection, rapid processing, and cost-effectiveness.Methods: A magnetically-assisted SERS biosensor was designed, employing wheat germ agglutinin (WGA) for broad-spectrum recognition and antibodies for specific capture. Gold nanostars (AuNSs) were sequentially modified with the Raman reporter molecules and WGA, creating a versatile SERS tag with high affinity for a diverse range of bacteria. Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) antibody-modified Fe3O4 magnetic gold nanoparticles (MGNPs) served as the capture probes. Target bacteria were captured by MGNPs and combined with SERS tags, forming a “sandwich” composite structure for bacterial detection.Results: AuNSs, with a core size of 65 nm, exhibited excellent storage stability (RSD=5.6%) and demonstrated superior SERS enhancement compared to colloidal gold nanoparticles. Efficient binding of S. aureus and P. aeruginosa to MGNPs resulted in capture efficiencies of 89.13% and 85.31%, respectively. Under optimized conditions, the developed assay achieved a limit of detection (LOD) of 7 CFU/mL for S. aureus and 5 CFU/mL for P. aeruginosa. The bacterial concentration (10– 106 CFU/mL) showed a strong linear correlation with the SERS intensity at 1331 cm− 1. Additionally, high recoveries (84.8% - 118.0%) and low RSD (6.21% - 11.42%) were observed in spiked human urine samples.Conclusion: This study introduces a simple and innovative magnetically-assisted SERS biosensor for the sensitive and quantitative detection of S. aureus or P. aeruginosa, utilizing WGA and antibodies. The developed biosensor enhances the capabilities of the “sandwich” type SERS biosensor, offering a novel and effective platform for accurate and timely clinical diagnosis of bacterial infections. Keywords: SERS, WGA, pathogenic bacteria, bacterial detection, dual-recognition

Keywords

• sers
• wga
• pathogenic bacteria
• bacterial detection
• dual-recognition