Optimization of Surface-Enhanced Raman Spectroscopy Detection Conditions for Interaction between Gonyautoxin and Its Aptamer

This study aimed to optimize the detection conditions for surface-enhanced Raman spectroscopy (SERS) of single-stranded DNA (ssDNA) in four different buffers and explore the interaction between gonyautoxin (GTX1/4) and its aptamer, GO18. The influence of the silver colloid solution and MgSO4 concentration (0.01 M) added under four different buffered conditions on DNA SERS detection was studied to determine the optimum detection conditions. We explored the interaction between GTX1/4 and GO18 under the same conditions as those in the systematic evolution of ligands by exponential enrichment technique, using Tris-HCl as the buffer. The characteristic peaks of GO18 and its G-quadruplex were detected in four different buffer solutions. The change in peak intensity at 1656 cm−1 confirmed that the binding site between GTX1/4 and GO18 was in the G-quadruplex plane. The relative intensity of the peak at 1656 cm−1 was selected for the GTX1/4–GO18 complex (I1656/I1099) to plot the ratio of GTX1/4 in the Tris-HCl buffer condition (including 30 μL of silver colloid solution and 2 μL of MgSO4), and a linear relationship was obtained as follows: Y = 0.1867X + 1.2205 (R2 = 0.9239). This study provides a basis for subsequent application of SERS in the detection of ssDNA, as well as the binding of small toxins and aptamers.

Silver Cluster Interactions with Tyrosine: Towards Amino Acid Detection

Tyrosine (Tyr) is involved in the synthesis of neurotransmitters, catecholamines, thyroid hormones, etc. Multiple pathologies are associated with impaired Tyr metabolism. Silver nanoclusters (Ag NCs) can be applied for colorimetric, fluorescent, and surface-enhanced Raman spectroscopy (SERS) detection of Tyr. However, one should understand the theoretical basics of interactions between Tyr and Ag NCs. Thereby, we calculated the binding energy (Eb) between Tyr and Agnq (n = 1–8; q = 0–2) NCs using the density functional theory (DFT) to find the most stable complexes. Since Ag NCs are synthesized on Tyr in an aqueous solution at pH 12.5, we studied Tyr−1, semiquinone (SemiQ−1), and Tyr−2. Ag32+ and Ag5+ had the highest Eb. The absorption spectrum of Tyr−2 significantly red-shifts with the attachment of Ag32+, which is prospective for colorimetric Tyr detection. Ag32+ interacts with all functional groups of SemiQ−1 (phenolate, amino group, and carboxylate), which makes detection of Tyr possible due to band emergence at 1324 cm−1 in the vibrational spectrum. The ground state charge transfer between Ag and carboxylate determines the band emergence at 1661 cm−1 in the Raman spectrum of the SemiQ−1–Ag32+ complex. Thus, the prospects of Tyr detection using silver nanoclusters were demonstrated.

A Simple Route for the Preparation of Gold Nanofilms and Their Application in SERS Detection of Pyrene in Water

Design and preparation of various rational gold nanostructures has been recognized as a promising solution for the surface-enhanced Raman scattering (SERS) signal amplification. Here, a simple fabrication method was reported for the synthesis of highly sensitive gold nanofilms for SERS detection through covering ginger-liked gold nanoparticles on the stainless steel sheet. The prepared gold nanofilms were then tested by a dip-SPME-SERS method for detecting pyrene. The limit of detection for pyrene standard solution was 0.1ppb, while the limit of detection for pyrene in tap water and lake water without any pretreatment was 5 ppb, respectively. The whole analysis process takes less than 15 minutes. Our method may be a potential alternative way to the chromatography method. The fabricated gold nanfilms are expected to be used for the rapid and sensitive detection of other pollutants such as organic pesticides and polycyclic aromatic hydrocarbon.

Ascorbic Acid Functionalized Anti-Aggregated Au Nanoparticles for Ultrafast MEF and SERS Detection of Tartrazine: An Ultra-Wide Piecewise Linear Range Study

Tartrazine, as a synthetic food colorant, is harmful to health upon excessive intake. In this work, we developed a simple, sensitive and ultrafast method to detect tartrazine effectively. Specifically, we...

Ultrasensitive Detection of Vitamin E by Signal Conversion Combined with Core-satellite Structure-based Plasmon Coupling Effect

Rapidly and sensitively surface-enhanced Raman scattering (SERS) detection of molecular biomarkers from real samples is still a challenge, because the intrinsically trace analytes may have a low molecular affinity for...

Quantitative Surface-Enhanced Spectroscopy

Surface-enhanced Raman scattering (SERS), a powerful technique for trace molecular detection, depends on chemical and electromagnetic enhancements. While recent advances in instrumentation and substrate design have expanded the utility, reproducibility, and quantitative capabilities of SERS, some challenges persist. In this review, advances in quantitative SERS detection are discussed as they relate to intermolecular interactions, surface selection rules, and target molecule solubility and accessibility. After a brief introduction to Raman scattering and SERS, impacts of surface selection rules and enhancement mechanisms are discussed as they relate to the observation of activation and deactivation of normal Raman modes in SERS. Next, experimental conditions that can be used to tune molecular affinity to and density near SERS substrates are summarized and considered while tuning these parameters are conveyed. Finally, successful examples of quantitative SERS detection are discussed, and future opportunities are outlined. Expected final online publication date for the Annual Review of Physical Chemistry, Volume 73 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.