TNF-α Detection Using Gold Nanoparticles as A Surface-Enhanced Raman Spectroscopy Substrate

Abstract

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.

Computational and Experimental Analysis of Gold Nanorods in Terms of Their Morphology: Spectral Absorption and Local Field Enhancement

“…Although constrained both spectrally and spatially, this strong field enhancement may boost the Raman signal, which would help to lower the limit of detection of substances or biomolecules. This application has been previously demonstrated in the detection of biological substances using gold nanoparticles with Raman spectroscopy [ 33 , 85 , 86 , 87 ]. Additionally, if the AuNRs are functionalized to trap specific biomolecules, the capabilities of these nanoparticles expand and could detect proteins, biomarkers, antigens, and other biological compounds.…”

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“…However, TNF-α plasma levels above 4.17 pg/mL are indicative of cardiovascular disease, the most common cause of mortality amongst DKD patients [ 121 ]. In addition, results can take between 2 and 4 weeks to obtain delaying diagnosis [ 122 ]. Thus, new approaches are required to use this cytokine as an accurate prognostic marker.…”

“…The Raman spectrum showed specificity and selectivity for TNF- α detection (limit of detection 1 pg/ mL), with minor signal display from negative controls including 0.05% bovine serum albumin, interleukin (IL)−1 and IL-8 at a concentration of 10 ng/ mL. More recently, unconjugated SERS have been reported to produce a limit of detection value of 0.125 pg/ mL [ 122 ]. Whilst the authors identified improved detection of TNF- α, this label-free approach is limited in its clinical application due to difficulties discerning different proteins within a given sample.…”

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