Search

The synthesis of three-dimensional silver nanopopcorns (Ag NPCs) onto a flexible polycarbonate membrane (PCM) for the detection of nitrofurazone (NFZ) on the fish surface by surface-enhanced Raman spectroscopy (SERS) is presented. The proposed flexible Ag-NPCs/PCM SERS substrate exhibits significant Raman signal intensity enhancement with the measured enhancement factor of 2.36 × 106. This is primarily attributed to the hotspots created on Ag NPCs, including numerous nanoscale protrusions and internal crevices distributed across the surface of Ag NPCs. The detection of NFZ by this flexible SERS substrate demonstrates a low limit of detection (LOD) of 3.7 × 10−9 M and uniform and reproducible Raman signal intensities with a relative standard deviation below 8.34%. It also exhibits excellent stability, retaining 70% of its efficacy even after 10 days of storage. Notably, the practical detection of NFZ in tap water, honey water, and fish surfaces achieves LOD values of 1.35 × 10−8 M, 5.76 × 10−7 M, and 3.61 × 10−8 M, respectively, which highlights its effectiveness across different sample types. The developed Ag-NPCs/PCM SERS substrate presents promising potential for sensitive SERS detection of toxic substances in real-world samples. [ABSTRACT FROM AUTHOR]

With the continuous development in nanoscience and nanotechnology, analytical techniques like surface-enhanced Raman spectroscopy (SERS) render structural and chemical information of a variety of analyte molecules in ultra-low concentration. Although this technique is making significant progress in various fields, the reproducibility of SERS measurements and sensitivity towards small molecules are still daunting challenges. In this regard, microfluidic surface-enhanced Raman spectroscopy (MF-SERS) is well on its way to join the toolbox of analytical chemists. This review article explains how MF-SERS is becoming a powerful tool in analytical chemistry. We critically present the developments in SERS substrates for microfluidic devices and how these substrates in microfluidic channels can improve the SERS sensitivity, reproducibility, and detection limit. We then introduce the building materials for microfluidic platforms and their types such as droplet, centrifugal, and digital microfluidics. Finally, we enumerate some challenges and future directions in microfluidic SERS. Overall, this article showcases the potential and versatility of microfluidic SERS in overcoming the inherent issues in the SERS technique and also discusses the advantage of adding SERS to the arsenal of microfluidics. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases cause enormous morbidity and mortality worldwide. Excessive blood total homocysteine (tHcy) is an independent risk factor for cardiovascular diseases. Therefore, it is imperative to measure the content of tHcy in human blood. However, the currently available analytical methods have the disadvantages such as being time-consuming and expensive. Herein, we propose a rapid clinical quantification of tHcy in human serum using high-performance Ag Nanopolyhedra (Ag NPOLY) as surface-enhanced Raman spectroscopy (SERS) substrates. Generally, 80% of homocysteine (Hcy) in serum is oxidized, and only 20% of Hcy is free. To understand this behavior, we explored the reduction effect of tris(2-carboxyethyl) phosphine (TCEP) on serum Hcy at different pH. The results confirmed that our method can detect 2 µM of Hcy in human serum. As a proof-of-concept, the developed method was applied to the actual clinical detection of human serum tHcy, and the serum of 5 hyperhomocysteinemia (HHcy) patients was verified. Moreover, the obtained, results were consistent with high-performance liquid chromatography (HPLC) results. The linear correlation coefficient of the two methods was 0.9766. Importantly, our analysis can be completed within 15 min, while HCLP requires more than 1 h. Overall, we have successfully developed a rapid SERS-based quantitative method for human serum tHcy, which can provide a new solution for the clinical diagnosis of cardiovascular diseases in the future. [Display omitted] • Constructed a high-performance Ag NPOLY for the detection of tHcy in human serum. • The detection limit for Hcy is 1 µM. • Discussed the optimal condition of TCEP for Hcy reduction. • This method allows the clinical quantification of tHcy. [ABSTRACT FROM AUTHOR]

Dioxin is a highly toxic and carcinogenic pollutant created during industrial production and waste incineration. Pollutant monitoring has made extensive use of surface-enhanced Raman spectroscopy (SERS) as a quick, non-destructive, sensitive, and affordable analytical method. However, the fabrication of a SERS substrate with ultrahigh sensitivity is a challenging task, the detection cost is expensive. Currently, these are the challenges faced by SERS technique for the detection of dioxin pollutants. In this paper, we present Au nanocakes (Au NCs) as an easy-to-build SERS substrate for sensitive SERS detection of dioxins in real samples. Based on three-dimensional finite-difference time-domain (3D-FDTD) calculations, the enhancement factor of the substrate following aggregation is approximately 1010. Using a portable Raman spectrometer, the limit of detection for dioxins such as 1-chloro-dibenzo-p-dioxin (1-CDD), 2,8-dichloro-dibenzo-p-dioxin (2,8-DCDD), and 2,3,7-trichloro-dibenzo-p-dioxin (2,3,7-TrCDD) in clean water reached as low as 5, 5, and 10 ng/mL, respectively. As a real-world application, the same toxic pollutants were detected in sewage water samples. Our findings could lead to the development of novel SERS-based sensors for the rapid detection of dioxins in real-world scenarios. Moreover, a portable Raman spectrometer is used to detect the pollutants, which is easy to use and inexpensive. [Display omitted] • Ultra-sensitive Au nanocake was constructed for detection of dioxins in water. • This facile approach provides a stable platform for field-based analysis. • All experimental data were measured by a portable Raman spectrometer with a detection limit of 5 ppb. [ABSTRACT FROM AUTHOR]