Gold nanobipyramids (Au NBPs) with two sharp tips present an extremely strong electric field enhancement, which endows them with more advantages in biomedical photonics than other gold nanostructures. The application of Au NBPs for diagnosis and therapy is now under intensive investigation. Here, we report Au NBPs for surface-enhanced Raman scattering (SERS) detection and photothermal therapy (PTT) of MCF-7 cancer cells both in vitro and in vivo via bioconjugation with Raman reporter 2-naphthalenethiol (2-NAP) and folic acid (FA). The results showed that bioconjugated Au NBPs not only could be used for the quantitative detection of the MCF-7 cells in the range of 5–500 cells/mL, but also lead to the enhanced Raman signal in MCF-7 tumor-bearing nude mice with high specificity. Moreover the bioconjugated Au NBPs exhibited excellent photothermal performance in both in vitro and in vivo therapies, in which the cell viability decreased to 6.44% and the relative volume of MCF-7 tumors treated with bioconjugated Au NBPs reduced to 0.037 under the irradiation of an 808 nm laser. Our results indicate that bioconjugated Au NBPs offer an excellent nanoplatform for PTT and SERS detection in the future.
A surface-enhanced Raman scattering (SERS) platform for the selective trace analysis of Hg2+ ions was reported, based on poly-thymine (T) aptamer/2-naphthalenethiol (2-NT)-modified gold nanoparticles (AuNPs), which was an oligonucleotide-functionalized nanosensor and SERS chip. 2-NT was used as a Raman reporter, and T aptamer could form a T-Hg2+-T structure with Hg2+ ions making an SERS nanosensor absorbed to the SERS chip. The optimum concentrations of DNA and 2-NT were obtained. An average of 960 DNA molecules attached to each AuNP were measured. The limit of detection (LOD) was 1.0 ppt (1.0 × 10−12 g/mL), which is far below the limit of 10.0 ppb for drinking water, stipulated by the World Health Organization. The sensor has the advantages of low detection cost, a simple sample pretreatment, a green solution and reducing false positives. Furthermore, the nanosensor was used for the determination of trace Hg2+ in the water of a lake; a reliable result was obtained accurately.
Breaking the limitation of smooth silver nanowires (Ag NWs) in forming sufficient “hot spots” is a crucial step to push them into practical surface enhancement Raman scattering (SERS)-based detection. Herein, Ag NWs with various etched configurations were developed by utilizing different amounts of aqua regia as etchant at room temperature . Compared with the smooth Ag NWs, more electromagnetic “hot spots” were enabled by the etched one, which exhibited better sensitivity and uniformity in SERS signals. The limit of detection (LOD) for 2-naphthalenethiol (2-NAT) obtained from the optimized substrate could reach 8.3 × 10 −10 mol/L and the relative standard deviation (RSD) was 6.8%. The maximum enhancement factor (EF) value obtained as 3.34 × 10 6 was even three times higher than that of the smooth one. Finally, an ultra-sensitive detection of thiram with a lowest detectable concentration of 4 × 10 −8 mol/L was facilitated by the optimal etched Ag NWs.
危险品化学品经营许可证（带存储）