Synchronous Fe³⁺-Enhanced Colorimetric and Liquid SERS-Based Detection of Dopamine Using Core–Shell Plasmonic Nanoparticles

Abstract

Reliable and direct detection of dopamine (DA), which is a crucial neurotransmitter, is required to diagnose dopamine-related diseases. However, the plasmonic colloidal sensing systems without prefunctionalization (e.g., aptamer, receptor, antibody, etc.) have not been well-established for trace DA detection yet. Herein, we develop a synchronous colorimetric and liquid-surface-enhanced Raman scattering (SERS) sensing system for the sensitive and selective detection of DA neurotransmitters using Au–Ag core–shell nanoparticles (Au@Ag CSNPs). The DA-mediated aggregation of Au@Ag CSNPs changed their plasmon resonance, leading to a distinct color change of the CSNP dispersion and generation of strong electromagnetic “hot spots” in the clustered CSNPs. Notably, the addition of Fe3+ ions to the CSNP dispersion intensified the DA-mediated aggregation of CSNPs, which significantly improved the colorimetric response and liquid-SERS detection of DA in the nanomolar range. Notably, the dual-mode sensing system without prefunctionalization demonstrated highly selective detection of the DA analyte against similar catecholamines (such as norepinephrine and epinephrine), which can be potentially applied to the selective discrimination of trace DA in real samples.

Quantification of Plasma Dopamine in Depressed Patients Using Silver-Enriched Silicon Nanowires as SERS-Active Substrates

“…After the HNO 3 treatment, the SiNW substrate did not exhibit virtually no Raman peak of DA as the silver was effectively removed. On the other hand, the SiNWs@Ag substrate displayed distinct DA peaks at 1148, 1293, 1382, and 1458 cm –1 , corresponding to ν15, C–O stretching, NH twisting, and ν19b, respectively. − The peaks at 1148 and 1458 cm –1 were attributed to the stretching vibrations of the C–N bond and ring stretching vibrations of the C–C bond with the attached oxygen, respectively . In addition, the typical DA peaks remain unaffected in the presence of AA.…”

SERS detection of dopamine using metal-chelated Ag nanoshell

“…This enhancement was mainly due to a decreased distance between the nanoprobes and targeted molecules. 47 Since the effect of surface plasmon spreads within a few nanometers, it is important to attract target molecules that are close to the surface of nanoprobes to amplify the SERS signal. If the attracted molecules with metal-chelation are located at “hotspots”, the intensity of the SERS signal can be strongly enhanced.…”

Breaking Barriers: Exploring Neurotransmitters through In Vivo vs. In Vitro Rivalry

“…Although SERS promises impressive sensitivity and selectivity, it requires specialized and complex equipment. Nonetheless, it remains a widely popular technique for neurotransmitter detection [ 30 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ]. In recent works, research teams are exploring implantable SERS-based nanoprobes for direct neurotransmitter detection in the brain [ 69 , 102 , 103 , 104 , 105 ].…”