Rapid and non-invasive surface-enhanced Raman spectroscopy (SERS) detection of chlorpyrifos in fruits using disposable paper-based substrates charged with gold nanoparticle/halloysite nanotube composites.

Chlorpyrifos is one of the most widely used organophosphate insecticides in agricultural production. Nevertheless, the residues of chlorpyrifos in agricultural by-product seriously threaten human health. Thus, the ultrasensitive detection of chlorpyrifos residues in agri-food products is of great demand. Herein, an AuNP/HNT-assembled disposable paper SERS substrate was prepared by an electrostatic self-assembly method to detect chlorpyrifos residues. The AuNP/HNT paper substrate exhibited high SERS activity, good reproducibility, and long-term stability, which was successfully used for quantitative detection of chlorpyrifos; the detection limit reached 7.9 × 10-9 M. For spiked apple samples the calculated recovery was 87.9% with a RSD value of 6.1%. The excellent detection ability of AuNP/HNT paper-based SERS substrate indicated that it will play an important role in pesticide detection in the future. AuNP/HNT assembled disposable paper SERS substrate was prepared by an electrostatic self-assembly method to detect chlorpyrifos residues in fruits.

HMGA2 promotes breast cancer metastasis by modulating Hippo-YAP signaling pathway.

BACKGROUND: Breast cancer is the most common cancer in women, and triple-negative breast cancer (TNBC) accounts for about 15-20% of all breast cancer. High mobility group AT-hook 2 (HMGA2) is overexpressed in some tumors and closely associated with patients' prognosis. However, the mechanisms involved in the regulation of HMGA2 in TNBC still remain unclear. METHODS: In this study, HMGA2 level in TNBC cell lines was analyzed by western blot. After knockdown of HMGA2 expression by RNA interference in TNBC cell lines MDA-MB-231 and SUM149, wound healing and transwell assays were conducted to examine the effects of HMGA2 on migration and invasion. Tumor metastasis was assessed in amouse xenograft model invivo. Furthermore, expression levels of epithelial-mesenchymal transition (EMT) biomarkers and involvement of the Hippo-YAP pathway were detected by western blot. RESULTS: Compared to normal breast epithelial cells, the expression levels of HMGA2 were significantly increased in TNBC cell lines (all P< .05). Downregulation of HMGA2 dramatically inhibited the migration and invasion of MDA-MB-231 and SUM149 cells (all P< .01) invitro, and suppressed the tumor metastasis of nude mice xenograft model invivo. Western blot analysis revealed alterations in EMT biomarkers: the expression of mesenchymal markers N-cadherin, Vimentin and Snail were decreased, while the expression of epithelial marker E-cadherin was increased. Downregulated expression of HMGA2 attenuated Hippo-YAP related protein expression and the stability of YAP. CONCLUSIONS: HMGA2 is highly expressed in TNBC cells. Downregulation of HMGA2 inhibits the migration and invasion of TNBC and invivo tumor metastasis mediated through inhibition of EMT and Hippo-YAP pathway.

Two-dimensional MXene modified AgNRs as a surface-enhanced Raman scattering substrate for sensitive determination of polychlorinated biphenyls.

Ultrathin two-dimensional MXene nanosheets were decorated on the surface of silver nanorods (AgNRs) through a facile modification strategy to prepare highly sensitive and reproducible SERS substrates (AgNR/MXene substrate). The MXene nanosheets could suppress the oxidation of the silver nanorods, which endows the substrate with good stability and reproducibility. Due to the strong interaction between AgNR/MXene and the analytes, the substrate also exhibited high SERS performance with the limit of detection (LOD) of crystal violet (CV) as low as 2.48 × 10-11 M. In particular, the AgNR/MXene substrate enabled on-site determination of 3,3',4,4'-tetrachlorobiphenyl (PCB-77) and 4-chlorobiphenyl (PCB-3) and the LODs were low at 2.43 × 10-10 and 2.14 × 10-9 M, respectively. In addition, the AgNR/MXene substrate could be used for the detection of single-component and multi-component PCBs in real soil samples with good recovery percentages (90.3% and 91.6% for PCB-3 and PCB-77 in single-component format, 108.1% and 106.5% for PCB-3 and PCB-77 in multi-component format). The AgNR/MXene substrate combines the synergistic properties of both AgNRs and MXene, showing great potential in simultaneous SERS detection of multiple pollutants at the point of need.

Fabrication of paper-based SERS substrates by spraying silver and gold nanoparticles for SERS determination of malachite green, methylene blue, and crystal violet in fish.

A disposable surface-enhanced Raman scattering (SERS) substrate was prepared by successively spraying silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) onto commercial filter paper using an inexpensive consumer sprayer. The strong surface enhancement of AgNPs and chemical stability of AuNPs can be advantageously combined. The substrate exhibited excellent SERS activity for malachite green (MG), methylene blue (MB), and crystal violet (CV) under 785-nm excitation, with limits of detection (LODs) of 4.3 × 10-9, 2.0 × 10-8, and 8.1 × 10-8 M, respectively. The substrate exhibited long-term stability, and it can be stored under ambient conditions for 4 weeks with a relative standard deviation of less than 3% among peak intensities. The substrate also showed good reproducibility with a relative standard deviation of 7.1% among different substrate peak intensities. The substrates enable on-site determination of residual fishery drugs and distinguish MG, MB, and CV mixtures in spiked fish within 5 min, and the average recoveries in fish scales and fish meat were better 90.1% and 76.9%, respectively. The method exhibited rapidity, simplicity, and high sensitivity and is expected to be used for the screening of additives in food.