Bimetallic flowers, beads, and buds: synthesis, characterization, and Raman imaging of unique mesostructures

Properties and applications of designable and photo/redox dual responsive surfactants with the new head group 2-arylazo-imidazolium

2-Arylazo-imidazolium grafted imidazolium surfactants with structural extensibility and reversible responsiveness to photo and electrochemical stimuli for further usage in a sol–gel process.

High specific detection and near-infrared photothermal therapy of lung cancer cells with high SERS active aptamer-silver-gold shell-core nanostructures

Lung cancer is the leading cause of cancer death worldwide. Its early detection is of paramount importance for diagnosis, classification, treatment, and improvement of survivorship. However, current methods are not sensitive enough to detect lung cancer in its nascent stage. We reported an aptamer-Ag-Au shell-core nanostructure-based surface-enhanced Raman scattering (SERS) assay for sensitive and specific detection, and near-infrared (NIR) photothermal therapy of lung adenocarcinoma cells (A549 cells). The nanostructures target the cells with high affinity and specificity via the specific interaction between the aptamer (a 45-base oligonucleotide) and the cell, and distinguish A549 cells from other types of cancer cells (HeLa and MCF-7 cells) and subtypes of lung cancer cells (NCI-H157, NCI-H520, NCI-H1299, and NCI-H446 cells). The nanostructures have a high capability to absorb NIR irradiation and are able to perform photothermal therapy of the cells at a very low irradiation power density (0.20 W cm(-2)) without destroying the healthy cells and the surrounding normal tissues. In addition, the nanostructures exhibit a high SERS activity. Based on the SERS signal of the labeled Raman reporter (Rh6G molecules), we can specifically detect A549 cells at a very low abundance (~10 cells per mL) and monitor the therapy process of the cancer cells. Therefore, this nanostructure-based SERS assay has great potential in specific recognition, sensitive detection, and effective photothermal therapy of lung cancer.

Aptamer-guided silver-gold bimetallic nanostructures with highly active surface-enhanced Raman scattering for specific detection and near-infrared photothermal therapy of human breast cancer cells

The aptamer (S2.2)-guided Ag-Au nanostructures (aptamer-Ag-Au) have been synthesized by photoreduction and validated by ultraviolet-visible light (UV-vis) spectra and transmission electron microscopy (TEM) images. Differential interference contrast (DIC), fluorescence, and TEM images, and surface-enhanced Raman scattering (SERS) spectra indicated that the aptamer-Ag-Au nanostructures can target the surface of human breast cancer cells (MCF-7) with high affinity and specificity. This targeting is completed via the specific interaction between S2.2 aptamer (a 25-base oligonucleotide) and MUC1 mucin (a large transmembrane glycoprotein, whose expression increased at least 10-fold at MCF-7 cells in primary and metastatic breast cancers). However, the nanostructures cannot target HepG2 (human liver cancer cells) or MCF-10A cells (human normal breast epithelial cells), because these cells are MUC1-negative expressed. Moreover, the synthesized nanostructures exhibited a high SERS activity. Based on these results, a new assay for specifically detecting MCF-7 cells has been proposed. This assay can also discriminate MCF-7 cells from MCF-10A cells and different cancer cell lines, such as HepG2 cells. In addition, the aptamer-Ag-Au nanostructures have a high capability of adsorpting near-infrared (NIR) irradiation and are able to perform photothermal therapy of MCF-7 cells at a very low irradiation power density (0.25 W/cm(2)) without destroying the healthy cells and the surrounding normal tissue. Therefore, the proposed assay is significant for the diagnosis of tumors in their nascent stage. The synthesized nanostructures could offer a protocol to specifically recognize and sensitively detect the cancer cells, and would have great potential for application in the photothermal therapy of the cancers.

Bimetallic mesoflowers: region-specific overgrowth and substrate dependent surface-enhanced Raman scattering at single particle level

A strategy for the preparation of bimetallic mesoflowers (MFs) has been demonstrated by a simple overgrowth reaction. We make hybrid MFs containing Au core and shells of different metals, such as Ag and Pt, by tuning the experimental conditions so as to study region-specific overgrowth. This selective growth is attributed to the specific binding affinity of cetyltrimethylammonium bromide (CTAB) at different crystal planes of Au MF surfaces. We also studied the region-specific, composition dependent surface-enhanced Raman scattering (SERS) activity of single bimetallic MFs to understand their chemical environment. Substrate effects on the SERS activity at single particle level were evaluated by a comparative study of the Raman images of Au, Au/Ag, and Au/Pt MFs. Region-specific SERS activity exhibited by single Au/Ag MF provides an insight into the SERS activity of bimetallic MFs over their monometallic analogues.