Tong Zhang,1– 3,* Han Wu,1,2,* Chenling Qiu,1,2 Mingxin Wang,1,2 Haiting Wang,1,2 Shunhua Zhu,1,4 Yinhai Xu,2 Qingli Huang,1,4 Shibao Li1,2 

1Medical Technology School of Xuzhou Medical University, Xuzhou, Jiangsu, 221000, People’s Republic of China; 2Department of Laboratory Medicine, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221000, People’s Republic of China; 3Chuzhou Center for Disease Control and Prevention, Chuzhou City, Anhui, 239000, People’s Republic of China; 4Public Experimental Research Center of Xuzhou Medical University, Xuzhou City, Jiangsu, 221004, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Qingli Huang; Shibao Li, Email qlhuang@xzhmu.edu.cn; sdjnshlb@xzhmu.edu.cn

Introduction: Insulin and C-peptide played crucial roles as clinical indicators for diabetes and certain liver diseases. However, there has been limited research on the simultaneous detection of insulin and C-peptide in trace serum. It is necessary to develop a novel method with high sensitivity and specificity for detecting insulin and C-peptide simultaneously.
Methods: A core-shell-satellites hierarchical structured nanocomposite was fabricated as SERS biosensor using a simple wet-chemical method, employing 4-MBA and DTNB for recognition and antibodies for specific capture. Gold nanorods (Au NRs) were modified with Raman reporter molecules and silver nanoparticles (Ag NPs), creating SERS tags with high sensitivity for detecting insulin and C-peptide. Antibody-modified commercial carboxylated magnetic bead@antibody served as the capture probes. Target materials were captured by probes and combined with SERS tags, forming a “sandwich” composite structure for subsequent detection.
Results: Under optimized conditions, the nanocomposite fabricated could be used to detect simultaneously for insulin and C-peptide with the detection limit of 4.29 × 10− 5 pM and 1.76 × 10− 10 nM in serum. The insulin concentration (4.29 × 10− 5– 4.29 pM) showed a strong linear correlation with the SERS intensity at 1075 cm− 1, with high recoveries (96.4– 105.3%) and low RSD (0.8%– 10.0%) in detecting human serum samples. Meanwhile, the C-peptide concentration (1.76 × 10− 10– 1.76 × 10− 3 nM) also showed a specific linear correlation with the SERS intensity at 1333 cm− 1, with recoveries 85.4%– 105.0% and RSD 1.7%– 10.8%.
Conclusion: This breakthrough provided a novel, sensitive, convenient and stable approach for clinical diagnosis of diabetes and certain liver diseases. Overall, our findings presented a significant contribution to the field of biomedical research, opening up new possibilities for improved diagnosis and monitoring of diabetes and liver diseases.

Keywords: surface-enhanced Raman scattering, SERS, nanocomposites, insulin, C-peptide