Metanephrine neuroendocrine tumor marker detection by SERS using Au nanoparticle/Au film sandwich architecture
Neuroendocrine tumors, such as pheochromocytoma or paraganglioma, are dangerous tumors that constitute a potential threat for a large number of patients. Currently, the biochemical diagnosis of neuroendocrine tumors is based on measurement of the direct secretory products of the adrenomedullary-sympathetic system or of their metabolites, such as catecholamines or their metanephrine derivatives, from plasma or urine. The techniques used for analysis of plasma free metanephrines, i.e. high-performance liquid chromatography or high-performance liquid chromatography coupled with mass-spectrometry are technically-demanding and time consuming, which limit their availability. Here we demonstrate a simple, fast and low-cost method for detecting metanephrine by Surface Enhanced Raman Scattering (SERS). The protocol consists in using evaporation-induced self-assembly of gold (Au) nanoparticles incubated with the analyte, on planar gold films. The assembly process produces regions with a dense distribution of both inter-particle gaps and particle-film gaps. Finite-difference time-domain simulations confirm that both kinds of gaps are locations of enhanced electromagnetic fields resulting from inter-particle and particle-film plasmonic coupling, useful for SERS amplification. Metanephrine vibrational bands assignment was performed according to density functional theory calculations. Metanephrine metabolite was detected in liquid at concentration levels lower than previously reported for other similar metabolites. The obtained results demonstrate that the Au nanoparticle/Au film exhibits noticeable SERS amplification of the adsorbed metabolite and can be used in the design of efficient, stable SERS-active substrates for the detection and identification of specific tumor markers.
KeywordsGold nanoparticles Nanobiosensor SERS detection Neuroendocrine tumor Metanephrine
High-performance liquid chromatography
Surface Enhanced Raman Scattering
Finite-difference time-domain simulations
Density functional theory
Enzyme-linked immunosorbent assay
Atomic force microscopy
Transmission Electron Microscopy
This work was supported by Babes-Bolyai University, Cluj-Napoca, Romania under the Research Grant for Young Scientists, Contract GTC-UBB No. 34056/2013. S. Boca acknowledges post-doctoral grant of the Romanian Ministry of Education, CNCS-UEFISCDI, Project number PN-II-RU-PD-2012-3-0111. M. Baia acknowledges COST action BM1401.
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Conflict of interest
The authors declare that they have no conflict of interest.
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