A lateral flow immunoassay with highly stable Au@Au SERS nanolabels for rapid free testosterone analysis

A highly stable Au@Au SERS nanolabels-based LFIA was developed for rapid FT analysis. • The AuNPs DTNB @Au exhibited high stability during a 90-day storage period with a RSD value of 7.71%. • The LOD of 2.27 fg mL −1 and the LDR of 10 fg mL −1 to 10 μg mL −1 were achieved. • The entire analysis process was completed within 15 min. Free testosterone (FT) serves as a crucial biomarker for endocrine assessment. Nevertheless, the rapid and accurate analysis of FT presents a significant challenge due to its low abundance and the interference from the matrix. In this study, we developed a lateral flow immunoassay (LFIA) integrated with gold-core gold-shell nanoparticles (Au@Au NPs)-based surface-enhanced Raman scattering (SERS) nanolabels for the rapid analysis of FT. The Raman signal molecules (RSMs) were embedded within the interstitial gap between the Au core and the Au shell, significantly contributing to SERS enhancement while also improving the stability of the SERS nanolabels. The proposed biosensor demonstrated a linear dynamic detection range (LDR) of 10 fg mL −1 to 10 μg mL −1 (R 2  = 0.9914) and a limit of detection (LOD) of 2.27 fg mL −1 , with the entire analysis process completed within 15 min. Additionally, the results indicated that the platform exhibited remarkable reproducibility, stability, and selectivity, along with reliable performance in human serum samples. This generates a simple, rapid, and highly sensitive strategy for FT detection, demonstrating considerable potential for point-of-care testing of low-abundance biomarkers. Download: Download high-res image (140KB) Download: Download full-size image