A direct detection of amino acids with surface-enhanced Raman scattering: Cu nanoparticle-coated copper vanadate nanoribbons from mechanochemistry

Surface-enhanced Raman scattering (SERS) spectra were measured for monolayers of various amino acids: L-methionine (Met), L-cysteine (Cys), L-glycine (Gly), L-leucine (Leu), L-phenylalanine (Phe), and L-proline (Pro) and their homodipeptides (Met-Met, Cys-Cys, Gly-Gly, Leu-Leu, Phe-Phe, and Pro-Pro) deposited onto a colloidal gold surface. Orientation of amino acids and their homodipeptides, as well as specific-competitive interactions of their functional groups with the gold surface, were predicted by detailed spectral analysis of the obtained SERS spectra. The analysis performed allowed us to propose a particular surface geometry for each amino acid and homodipeptide on the gold surface. In addition, we compared the structures of these molecules adsorbed on colloidal gold and silver surfaces.

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60-nt DNA Direct Detection without Pretreatment by Surface-Enhanced Raman Scattering with Polycationic Modified Ag Microcrystal Derived from AgCl Cube

Molecules ◽

10.3390/molecules26226790 ◽

2021 ◽

Vol 26 (22) ◽

pp. 6790

Author(s):

Jikai Mao ◽

Lvtao Huang ◽

Li Fan ◽

Fang Chen ◽

Jingan Lou ◽

...

Keyword(s):

Raman Scattering ◽

Direct Detection ◽

Pure Water ◽

Real Life ◽

Surface Enhanced Raman Scattering ◽

Hereditary Diseases ◽

Label Free Detection ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering

Direct detection of long-strand DNA by surface-enhanced Raman scattering (SERS) is a valuable method for diagnosis of hereditary diseases, but it is currently limited to less than 25-nt DNA strand in pure water, which makes this approach unsuitable for many real-life applications. Here, we report a 60-nt DNA label-free detection strategy without pretreatment by SERS with polyquaternium-modified Ag microcrystals derived from an AgCl cube. Through the reduction-induced decomposition, the size of the about 3 × 3 × 3 μm3 AgCl cube is reduced to Ag, and the surface is distributed with the uniform size of 63 nm silver nanoparticles, providing a large area of a robust and highly electromagnetic enhancement region. The modified polycationic molecule enhances the non-specific electrostatic interaction with the phosphate group, thereby anchoring DNA strands firmly to the SERS enhanced region intactly. As a result, the single-base recognition ability of this strategy reaches 60-nt and is successfully applied to detect thalassemia-related mutation genes.

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Capture of Phenylalanine and Phenylalanine-Terminated Peptides Using a Supramolecular Macrocycle for Surface-Enhanced Raman Scattering Detection

Applied Spectroscopy ◽

10.1177/0003702820937333 ◽

2020 ◽

Vol 74 (11) ◽

pp. 1374-1383

Author(s):

Jacob E. Olson ◽

Adam S. Braegelman ◽

Lei Zou ◽

Matthew J. Webber ◽

Jon P. Camden

Keyword(s):

Raman Scattering ◽

Direct Detection ◽

Surface Enhanced Raman Scattering ◽

Detection Methods ◽

General Strategy ◽

Trace Detection ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Nanoparticle Aggregates ◽

Enhanced Raman Scattering

The cucurbit[n]uril (CB[ n]) family of macrocycles are known to bind a variety of small molecules with high affinity. These motifs thus have promise in an ever-growing list of trace detection methods. Surface-enhanced Raman scattering (SERS) detection schemes employing CB[ n] motifs exhibit increased sensitivity due to selective concentration of the analyte at the nanoparticle surface, coupled with the ability of CB[ n] to facilitate the formation of well-defined electromagnetic hot spots. Herein, we report a CB[7] SERS assay for quantification of phenylalanine (Phe) and further demonstrate its utility for detecting peptides with an N-terminal Phe. The CB[7]–guest interaction improves the sensitivity 5–25-fold over direct detection of Phe using citrate-capped silver nanoparticle aggregates, enabling use of a portable Raman system. We further illustrate detection of insulin via binding of CB[7] to the N-terminal Phe residue on its B-chain, suggesting a general strategy for detecting Phe-terminated peptides of clinically relevant biomolecules.

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