TNF-α detection using gold nanoparticles as a surface-enhanced Raman spectroscopy substrate

Background: TNF-α is a cytokine involved in inflammation. Surface-enhanced Raman spectroscopy (SERS) could be useful in its detection. Aim: Identify the TNF-α in an aqueous solution, using gold nanoparticles (AuNPs) as a SERS substrate. Materials & methods: Raman and SERS spectra were obtained from TNF-α samples, combined with AuNPs, with decreasing concentrations of TNF-α. The samples were analyzed using optical transmission spectroscopy, dynamic light scattering, and transmission electron microscopy. Results: Transmission electron microscopy/dynamic light scattering determined a change in the average diameter of the TNF-α/AuNPs (∼9.6 nm). Raman bands obtained were associated with aromatic amino acid side chains. We observe Raman signals for TNF-α concentrations as low as 0.125 pg/ml. Conclusion: TNF-α signal at physiological concentrations was determined with SERS.