A Rapid Detection Method for On-site Screening of Estazolam in Beverages with Au@Ag Core-shell Nanoparticles Paper-based SERS Substrate.

Estazolam (EST) is a common sedative-hypnotic drug with a risk of abuse. Therefore, rapid on-site detection of EST is necessary to control the abuse of EST. In this paper, a fast, simple, and sensitive method is demonstrated for the detection of EST in both water and beverages, using surface-enhanced Raman spectroscopy (SERS) techniques. Au@Ag core-shell nanoparticles (NPs) assembled on the filter paper as a SERS substrate exhibit good applicability and practicality. At the same time, density functional theory (DFT) is used to assign the vibration mode of the EST molecules, which can be used as a guide for subsequent experiments. The lowest detectable concentration of EST in aqueous solution can be as low as 5 mg/L, and signal uniformity is excellent (RSD687 = 5.56%, RSD1000 = 4.35%). In addition, EST components artificially added to orange juice and pomegranate juice can be effectively detected by simple pretreatment with a minimum detection concentration as low as 10 mg/L. Therefore, this study found that the use of Au@Ag core-shell nanoparticles paper-based SERS substrate provides a quick and easy method for the detection of illegally added drugs in beverages.

Rapid and Sensitive Surface-enhanced Raman Spectroscopy Method for Determination of Ketamine in Urine.

Surface-enhanced Raman spectroscopy (SERS) has gradually proved to be a powerful tool with wide applications in various fields. Here, a simple and rapid SERS method was developed for the determination of ketamine in urine based on silver aggregates as a SERS substrate. Ketamine in urine were demonstrated by the SERS technique with silver sol aggregated by a 0.5 M NaBr solution. The limit of detection for ketamine in urine could be obtained as low as 7.5 ppm, and a linear relationship for ketamine in urine between the Raman intensity and the concentrations was achieved in the range from 7.5 to 150 ppm (R2 = 0.977). Additionally, the recovery of this method ranged from 95.7 to 104.9%, which laid a favorable foundation for the rapid and reliable quantitative detection of ketamine in urine. Therefore, this SERS approach with high sensitivity and simplicity has a great prospect for the real-world application of ketamine in urine.

Detection and Quantification of Bucinnazine Hydrochloride Injection Based on SERS Technology.

In this investigation, surface-enhanced Raman spectroscopy (SERS) technology was performed to detect bucinnazine hydrochloride (BH) injection in water and urine. The theoretical Raman spectrum of BH with characteristic peaks was calculated and identified by density functional theory (DFT). Employing an improved silver sol as a SERS active substrate, the SERS spectra of a BH solution with different concentrations were acquired with a 0.5 mol/L KI solution as an aggregation agent. It was determined that the limit of detection (LOD) was low, to 0.01 µg/mL. A good linear relationship of BH between the Raman intensity and the concentrations was obtained in water at a concentration range from 0.5 to 6 µg/mL (R2 = 0.9914), which laid a favorable foundation for quantitative analysis. In addition, the recovery rate of spiked samples from 95.13 to 120.54% were calculated. Finally, the detection of BH injection in artificial urine was completed and the detection limit could reach 0.5 µg/mL, which met the requirements of a rapid on-site detection of drugs in urine. As a result, it indicates that the inspection of BH by the SERS method is with simplicity and high sensitivity, having a great potential for real-time detection.

Detection of Scopolamine Hydrobromide via Surface-enhanced Raman Spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) was used to measure scopolamine hydrobromide. First, the Raman characteristic peaks of scopolamine hydrobromide were assigned, and the characteristic peaks were determined. The optimal aggregation agent was potassium iodide based on a comparative experimental study. Finally, the SERS spectrum of scopolamine hydrobromide was detected in aqueous solution, and the semi-quantitative analysis and the recovery rate were determined via a linear fitting. The detection limit of scopolamine hydrobromide in aqueous solution was 0.5 µg/mL. From 0 - 10 µg/mL, the curve of the intensity of the Raman characteristic peak of scopolamine hydrobromide at 1002 cm-1 is y = 4017.76 + 642.47x. The correlation coefficient was R2 = 0.983, the recovery was 98.5 - 109.7%, and the relative standard deviation (RSD) was about 5.5%. This method is fast, accurate, non-destructive and simple for the detection of scopolamine hydrobromide.

Rapid Detection of Diazepam Injection Based on Surface Enhanced Raman Spectroscopy.

Diazepam injection was detected based on a droplet surface enhanced Raman spectroscopy (SERS) platform, which overcomes the disadvantages of the poor uniformity and time-consuming sample treatment process of the conventional "drop and dry" detection strategy. The Raman peak positions of diazepam injection were determined and identified, they are mainly located in the 689, 1002, 1170 and 1598 cm-1, etc. Different concentrations of diazepam injection were detected. It was found that the intensity of 1002 cm-1 increases linearly with concentration in the range from 0.05 to 10 µg/mL and the linear correlation coefficient is 0.988. The limit of detection can reach 0.05 µg/mL. The SERS method is easy, fast and efficient. The results are accurate and reliable. It has favorable application potential in the detection of diazepam injection.

Fabrication of transparent SERS platform via interface self-assembly of gold nanorods and gel trapping technique for on-site real time detection.

A transparent SERS platform was fabricated via the gel-trapping method coupled with a liquid/liquid interface self-assembly technique. We employed gold nanorods as the building blocks for interface self-assembly because of their strong localized surface plasmons upon excitation by infrared radiation. Based on a "top cover" configuration, this transparent SERS platform endows high signal reproducibility for directly detecting liquid samples by confining the sample droplet into a regular shape. The Au NR PDMS platform was able to directly detect crystal violet in aqueous solutions down to 10 ppb level with high enhancement factor (0.87 × 10(5)) and signal uniformity (RSD = 3.9%). Furthermore, SERS-based anti-fungal agent detection on a fish scale was demonstrated by simply covering the fish scale with a tailored GNRs PDMS film. The experimental results clearly show that the Au NR PDMS SERS platform has great potential for on-site real time detection of contaminants in water as well as on curved surfaces.