Determination of L-selectin in blood plasma using DNA aptamer-based surface-enhanced Raman spectroscopy assay

In the human body, tumor cell occurrence can be indirectly monitored using the L-selectin concentration in the blood, since selectin ligands are present on the surface of tumor cells, and with tumor progression, a decrease in L-selectin levels can be expected and observed. In this study, we present a selective DNA-based surface-enhanced Raman spectroscopy (SERS) assay for the detection and determination of L-selectin in biological samples. Two calibration curves (linear in the 40-190 ng mL^-1 region and exponential in the 40-500 ng mL^-1 region) are fitted to the obtained SERS experimental data, i.e., the ratio of I₇₃₂/I₁₃₃₄ band intensities (LOQ = 46 ng mL^-1). Calculated determination coefficients are found to be R² = 0.997 for the linear region of the calibration curve and R² = 0.977 for the exponential region. Moreover, we demonstrate very good selectivity of the assay even in the presence of P- and E-selectin in a sample containing L-selectin. With our SERS assay, the L-selectin concentration in biological samples can be estimated directly from the calibration curves.