A surface-enhanced Raman scattering (SERS) based microRNA (miRNA) probe was designed using molecular beacon (MB). In such a probe, silver nanoparticles were employed as the SERS substrate while 6-FAM was selected as a Raman reporter, which were connected by a hairpin shaped DNA. In the presence of target miRNA, the hairpin opened, making 6-FAM far away from the substrate with a decreased SERS intensity. As the concentration of the targets increased, the SERS intensity of Raman reporters decreased. Thus, according to the intensity-concentration calibration curve, the detection of miRNA-21 could be realized. The convenient, stable and sensitive detection method holds potential in the application of diagnosis.
Dual-drug delivery systems designed for effective therapy is receiving much attention in cancer treatment, however, monitoring of the stimuli-responsive multi-drug release dynamics in living cells is still challenging. Here, a dual drug nanocarrier has been successfully synthesized using functionalized carbon nanotubes (CNTs). To obtain effective combination therapy, CNTs are used for loading dual drugs, that is, 6-thioguanine (6TG) and doxorubicin (DOX).By using label-free surface enhanced Raman scattering (SERS) and fluorescence techniques, the release dynamics of the loaded two kinds of drugs can be traced in living cells. In this nanocarrier, 6TG was conjugated to the surfaces of gold-silver core-shell nanoparticles (Au@Ag NPs). Release of 6TG can be triggered by glutathione (GSH). DOX was loaded onto CNTs surfaces via π–π stacking, which exhibits a pH-responsive release behavior. To investigate the intracellular traceable delivery performance of this nanocarrier, the dual drug loaded nanocarrier was incubated with living HeLa cells. Experimental results indicated that this dual drug nanocarrier can effectively enter into HeLa cells. And the release of 6TG and DOX were triggered by the substation of GSH and the acidic environment of lysosomes, respectively. By recording the real-time SERS and fluorescence signals of dual-drug inside HeLa cells, we can successfully monitor the dynamic process of intracellular drug release. Moreover, the combination of 6TG and DOX exhibited a synergistic effect to enhance the efficacy of cancer therapy. This kind of dual drug nanocarrier presents a new perspective for the design of smart multi-drug delivery systems for cancer therapy.
Due to their unique properties, liposomes have been widely used as drug nanocarriers. Herein a liposome-Au nanohybrid has been demonstrated as a SERS active intracellular drug nanocarrier. In this study, cationic Raman reporter tagged gold nanoparticles (Au@4MBA@PAH) were anchored onto the surfaces of anionic liposomes via electrostatic interactions. Using SKBR3 cells as model cells, we revealed that the hybrid formulation can be effectively taken up by tumor cells and tracked by the SERS signals. Collectively, the liposome-Au nanohybrids hold great promise in biomedical applications.
Mesoporous silica nanospheres(MSNSs) have been obtained utilizing the conventional reverse micelles synthesis method while the mesoporous silica nanorods(MSNRs) have been acquired by means of changing certain parameters. Afterwards, the prepared mesoporous silica nanospheres and nanorods were used as drug carriers to load and release the classical cancer therapeutic drug—DOX. According to the absorption spectra, the encapsulation efficiency of the mesoporous silica nanospheres is almost as high as that of the nanospheres. Different from the familiar encapsulation efficiency, the release characteristic curves of the mesoporous silica nanospheres and nanorods possessed certain differences during the release process. Finally incellular fluorescence imaging was achieved to observe the endocytosis of the mesoporous silica materials. Our results show that although both of the two kinds of nanoparticles possess favourable properties for loading and releasing drugs, the mesoporous silica nanospheres perform better in dispersity and controlled release than the nanorods, which probably endow them the potential as incellular drug delivery system.
A sensitive SERS (surface-enhanced Raman scattering)-based immunoassay in microfluidic system has been developed with in-situ synthesis of gold substrate and immune reporter named as 4MBA (4-Mercaptobenzoic acid)-labeled immuno-Ag aggregates. The gold substrate was fabricated simply by introducing the hydrogen tetrachloroaurate (III) trihydrate (HAuCl4) solution to microchannels using a microfluidic pump. It was found that the obtained deposited gold nanoparticles were uniform in size and shape. Then the sandwich immunoassays were performed using the gold substrates based on SERS signals. In the immunoassay, the gold nanoparticles decorated surface was modified with certain antibodies to recognize the specific kind of antigen, which was flowed through the microfluidic channel afterwards. Then 4MBA-labeled immuno-Ag aggregates were employed as the SERS probes to quantitatively detect the antigen. The experimental results showed a good specificity and limit of detection (LOD) about 1 ng/mL.
Research continues in an effort to develop a versatile platform for clinical diagnosis with easy operation and low cost. In the present study, a biosensor chip has been designed and fabricated for surface enhanced Raman scattering (SERS)- fluorescence dual mode immunoassay. Here, a dual channel microfluidic chip was employed for simultaneous SERS and fluorescence detection. Unlike previously reported microfluidic immunoassays using fluorescence or SERS method independently, the proposed dual mode biosensor combined the advantages of these two optical detection techniques. The fluorescence mode can be used for fast screening of biomolecules while the SERS mode can be employed for accurate and sensitive quantitative analysis. In addition, the chip-based microfluidic platform greatly reduced the reagents cost and complicated operation. The whole detection process from sample preparation to optical detection can be finished in 90 min. Moreover, the reversibly bonded biosensor chip could be reused after cleaning, which further reduced the cost for each assay. All these merits make it a potential powerful tool for practical clinical diagnosis.
Optical probes are now routinely used in a remarkable number of imaging applications in the life sciences and medicine. We report the design, synthesis and characterization of a novel nanoprobe for biological applications based on surface enhanced Raman scattering (SERS). Specifically, the nanoprobe consists of magnetic Fe3O4 nanoparticles immobilized with silver nanoparticles and SERS tags. An efficient cellular uptake has been confirmed with confocal laser scanning microscopy. The nanoprobe retains its excellent SERS signals when incorporated into a cell. Besides, the probe also delivers spatially localized chemical information from its biological environments. The multi-functional probe is likely to be useful to develop new tools for targeted molecular probing of cells and provide a new way to monitor the complex changes at cellular level.
For the high absorption loss of the Electro-optic (EO) polymers, there are only a few reports on polymeric EO switches.
This paper presents a new design and fabrication method of the polymer 1×2 Mach-Zehnder Interference (MZI) switch
operating at 1550nm. The switch is consists of two vertically coupled waveguides located at different levels. And it will
be easier to fabricate by traditional technology. The finite difference Beam Propagation Method (BPM) has been used to
analyze the device propagation characteristics. The result indicated that the propagation loss of this Three-dimensional
(3-D) switch is decreased 2dB by that of the ordinary two-dimensional (2-D) switch. And this kind of structure has high
potential for the application of low-loss optical modulator and attenuator.
A wideband double-pass discrete Raman amplifier with high gain efficiency and improved gain polarization dependence is reported. In this Raman amplifier, by using a one-end gilded fiber as the broadband reflector, both signals and pumps are reflected to propagate through the gain fiber in the opposite direction of the input. An increase in net gain and an improved polarization dependence of Raman gain have been achieved compared with that in a typical co-pumped Raman amplifier. The advantages of this proposed new configuration have been studied experimentally.
By introducing the feature of tree-structured wavelet transform, a novel texture image retrieval method is proposed in this paper. The method can produce eigenfeature at different scales precisely by decomposing the texture at multi-scales and multi-directions adaptively under the energy rule. In terms of these image eigenvalues, the method also suggested a modified algorithm, named Principal Eigenvalues Analysis (PEA), which can cut down eigenfeature dimensions effectively. It was confirmed that on the capability of the hierarchical way provided by this method the use-oriented application processing can allow users to carry out different retrieval on accord to users' requirements, which is called a coarse to fine retrieval. It was indicated by experimental results that the modified texture retrieval way have powerful practical merits for it can improve the retrieval accuracy efficiently and speed up the retrieval processing.
Two new techniques have been proposed for outgassing the metal parts of helium cadmium lasers of the positive column type. The first method, double-way exhausting method, is mainly for cadmium outgassing; the second one, auxiliary anode method, is especially for cathode cylinder outgassing.
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