ИСТИНА

Bilirubin (BR) is a product of hemoglobin breakdown, increasing the level of which in the blood may indicate liver disorders and lead to jaundice. Kernicterus is most dangerous in newborns when the unconjugated BR concentration can quickly rise to toxic levels, causing neurological damage and even death. Developing accurate, fast, and sensitive sensor for BR detection will help reduce diagnostic time and ensure successful treatment. In this study, we created a SERS-active substrate based on gold-decorated silicon nanowires (Au@SiNWs) for sensitive label-free BR detection. Gold-assisted chemical etching of crystalline silicon wafers was used to synthesize SiNWs, the tops of which were then additionally decorated with gold nanoparticles. The low detection limit of model analyte 4-mercaptopyridine down to the concentration of 10-8 M demonstrated the excellent sensitivity of the obtained substrates for SERS application. The performed theoretical full-wave electromagnetic simulations of Raman scattering in Au@SiNW substrates showed, that the major contribution to the total SERS signal comes from the analyte molecules, located on SiNW surface near gold nanoparticles. Therefore, for efficient BR adsorption and SERS detection, the surface of SiNWs was modified with amino groups. Label-free detection of BR using amino modified Au@SiNWs with high point-to-point and scan-to-scan reproducibility up to concentrations of 10- 6 M has been demonstrated, which is the required sensitivity for clinical applications.