Sensitive determination of dopamine levels via surface-enhanced Raman scattering of Ag nanoparticle dimers

Abstract

BackgroundDopamine (DA) is an important neurotransmitter in the hypothalamus and pituitary gland, which can produce a direct influence on mammals’ emotions in midbrain. Additionally, the level of DA is highly related with some important neurologic diseases such as schizophrenia, Parkinson, and Huntington’s diseases, etc. In light of the important roles that DA plays in the disease modulation, it is of considerable significance to develop a sensitive and reproducible approach for monitoring DA.PurposeThe objective of this study was to develop an efficient approach to quantitatively monitor the level of DA using Ag nanoparticle (NP) dimers and enhanced Raman spectroscopy.MethodsAg NP dimers were synthesized for the sensitive detection of DA via surface-enhanced Raman scattering (SERS). Citrate was used as both the capping agent of NPs and sensing agent to DA, which is self-assembled on the surface of Ag NP dimers by reacting with the surface carboxyl group to form a stable amide bond. To improve accuracy and precision, the multiplicative effects model for surface-enhanced Raman spectroscopy was utilized to analyze the SERS assays.ResultsA low limits of detection (LOD) of 20 pM and a wide linear response range from 30 pM to 300 nM were obtained for DA quantitative detection. The SERS enhancement factor was theoretically valued at approximately 107 by discrete dipole approximation. DA was self-assembled on the citrate capped surface of Ag NPs dimers through the amide bond. The adsorption energy was estimated to be 256 KJ/mol using the Langmuir isotherm model. The density functional theory was used to simulate the spectral characteristics of SERS during the adsorption of DA on the surface of the Ag dimers. Furthermore, to improve the accuracy and precision of quantitative analysis of SERS assays with a multiplicative effects model for surface-enhanced Raman spectroscopy.ConclusionA LOD of 20 pM DA-level was obtained, and the linear response ranged from 30 pM to 300 nM for quantitative DA detection. The absolute relative percentage error was 4.22% between the real and predicted DA concentrations. This detection scheme is expected to have good applications in the prevention and diagnosis of certain diseases caused by disorders in the DA level.

Raman spectroscopy in cell biology and microbiology

“…[ 170 ] In a recent paper, Silwal et al [ 167 ] have applied surface enhanced Raman scattering to find spectral signatures of dopamine transporter interaction in living cells. In a further study, Yu et al [ 165 ] assigned the sharp Raman band of dopamine located at 1558 cm −1 to in‐plane bending vibration of its benzene ring (cf. also Table S2).…”

“…Figure 4b,c and Table S2). [40,58,103,[163][164][165][166][167] On the other hand, the Raman map in Figure 19d was built up by using the ratio between the intensities of the signals at 1565 and 1660 cm À1 , I 1565 /I 1660 . The signal at 1565 cm À1 is a quite sharp feature, which apparently belongs to a triplet assigned to CH 2 and NH 2 scissoring in dopaminequinone (cf.…”

Reusable Surface-Enhanced Raman Spectroscopy Substrates Made of Silicon Nanowire Array Coated with Silver Nanoparticles Fabricated by Metal-Assisted Chemical Etching and Photonic Reduction

“…Figure 5c shows the Raman spectrum obtained from a 10 −5 M DA solution using our prepared SERS substrate, and the detection limit is lower than 10 −7 M DA solution (Supporting information, Figure S5). The main Raman peaks of DA were successfully identified, including those at 1106, 1554, and 1630 cm −1 ascribed to the in-plane –OH bending vibration, and the in-plane bending vibration arising from the benzene ring and hydroxyl, respectively [34,35].…”

Functionalization of metal Nanoparticles for SERS-based Detections of illicit drugs in biological samples

“…In another study, Yu et al 27 proposed a method to quantitively monitor the level of Cocaine is a highly addictive drug that can heighten activity in the body, including heart rate, blood pressure, alertness, and energy. Except for approved medical use, there is no safe way to use cocaine in any form.…”