A core-satellite self-assembled SERS aptasensor containing a“biological-silent region”Raman tag for the accurate and ultrasensitive detection of histamine

Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-satellite SERS aptasensor was constructed by combining aptamer-decorated Fe_(3)O_(4)@Au MNPs(as the recognize probe for histamine)and complementary DNA-modified silver nanoparticles carrying 4-mercaptobenzonitrile(4-MBN)(Ag@4-MBN@Ag-c-DNA)as the SERS signal probe for the indirect detection of histamine.Under an applied magnetic field in the absence of histamine,the assembly gave an intense Raman signal at“Raman biological-silent”region due to 4-MBN.In the presence of histamine,the Ag@4-MBN@Ag-c-DNA SERS-tag was released from the Fe_(3)O_(4)@Au MNPs,thus decreasing the SERS signal.Under optimal conditions,an ultra-low limit of detection of 0.65×10^(-3)ng/mL and a linear range 10^(-2)-10^5 ng/mL on the SERS aptasensor were obtained.The histamine content in four food samples were analyzed using the SERS aptasensor,with the results consistent with those determined by high performance liquid chromatography.The present work highlights the merits of indirect strategies for the ultrasensitive and highly selective SERS detection of small biological molecules in complex matrices.

Macrophage-derived SHP-2 inhibits the metastasis of colorectal cancer via Tie2-PI3K signals

This research aimed to explore the influence of Src homology-2 containing protein tyrosine phosphatase(SHP-2)on the functions of tyrosine kinase receptors with immunoglobulin and EGF homology domains 2(Tie2)-expressing monocyte/macrophages(TEMs)and the influence of the angiopoietin(Ang)/Tie2-phosphatidylinositol-3-kinase(PI3K)/protein kinase B(Akt)/mammalian target of rapamycin(mTOR)(Ang/Tie2-PI3K/Akt/mTOR)signaling pathway on the tumor microvascular remodeling in an immunosuppressive microenvironment.In vivo,SHP-2-deficient mice were used to construct colorectal cancer(CRC)liver metastasis models.SHP-2-deficient mice had significantly more metastatic cancer and inhibited nodules on the liver surface than wild-type mice,and the high-level expression of p-Tie2 was found in the liver tissue of the macrophages’specific SHP-2-deficient mice(SHP-2MACKO)+planted tumor mice.Compared with the SHP-2 wild type mice(SHP-2WT)+planted tumor group,the SHP-2MAC-KO+planted tumor group experienced increased expression of p-Tie2,p-PI3K,p-Akt,p-mTOR,vascular endothelial growth factor(VEGF),cyclooxygenase-2(COX-2),matrix metalloproteinase 2(MMP2),and MMP9 in the liver tissue.TEMs selected by in vitro experiments were co-cultured with remodeling endothelial cells and tumor cells as carriers.It was found that when Angpt1/2 was used for stimulation,the SHP-2MAC-KO+Angpt1/2 group displayed evident increases in the expression of the Ang/Tie2-PI3K/Akt/mTOR pathway.The number of cells passing through the lower chamber and the basement membrane and the number of blood vessels formed by cells compared with the SHP-2WT+Angpt1/2 group,while these indexes were subjected to no changes under the simultaneous stimulation of Angpt1/2+Neamine.To sum up,the conditional knockout of SHP-2 can activate the Ang/Tie2-PI3K/Akt/mTOR pathway in TEMs,thereby strengthening tumor micro angiogenesis in the microenvironment and facilitating CRC liver metastasis.

SERS-tag techology in food safety and detection:sensing from the"fingerprint"region to the"biological-silent"region

Surface enhanced Raman spectroscopy(SERS)offers many advantages for the fast and sensitive detection of specific compounds,metal ions or pathogens in foods,motivating to its increasing utilization in food safety.SERS-tags,typically constructed using signal enhanced substrate,Raman reporter molecules,a biocompatible protective layer and a specific recognition element,provide a powerful tool for the analysis of food hazards.This article reviews recent progress in the development of SERS-tags for food safety assessment covering SERS-tags with characteristic peaks in the“fingerprint”region(800-1800 cm-1)and the“biological-silent”region(1800-2800 cm-1).Following a brief description of SERS substrates,the design,synthesis and applications of SERS-tag are explored in detail.The application of SERS-tags technology for the detection of microorganisms,pesticides and antibiotics are then investigated.Finally,the prospects of using SERS-tag in real-world food safety analysis are critically discussed.