The ultratrace detection of crystal violet using surface enhanced Raman scattering on colloidal Ag nanoparticles prepared by electrolysis

Highly active, stable and affordable surface enhanced Raman scattering （SERS） substrates were obtained by electrolyzing a mixture of AgNO3 （4 × 10^-4 mol/L） and Na3C6H5OTH2O （6 × 10^-5 mol/L） for 1, 2, 3 and 4 h at 7 V. With crystal violet （CV） as a test molecule, a portable Raman spectrometer with 785 nm laser excitation was employed to carry out the SERS detection. Colloidal Ag nanoparticles prepared by electrolyzing for 3 h with the particle size of （65 ±17） nm is a perfect SERS substrate for the ultratrace detection of CV, which displayed an enhancement factor of ca. 1.3 × 10^8 and the detection limit of CV is down to ca. 10-15 mol/L （ca. 10^-4 ppb） with 10^-1 mol/L KBr as aggregating agent. Thus, this SERS substrate will provide a hopeful foreground in ultratrace detection. Meanwhile, it will provide a possibility to bring Raman analysis out of the laboratory to process in situ, real-time detection and identification.

Degradation of crystal violet using nanometer TiO_2 under the synergistic action of H_2O_2 and ultrasonic wave

TiO_2 nanoparticles with different phases are prepared by hydrolysis oftitanium tetrabutoxide in the presence of HC1. The composition and microstructure of the resultingsamples are studied by XRD and TEM. These results show that the range of particle size of TiO_2 isfrom 20 to 30 nm. The mechanism of TiO_2 photocatalysis reaction has been discussed extensively.Photocatalytic activities of nanometer TiO_2 are also evaluated by degradation of the crystal violetsolution. Experimental results indicate that the synergistic action of H_2O_2 and ultrasonic wavegreatly enhances photo-catalytic reaction of TiO_2.

Molecularly Imprinted Polymers for Selective Extraction of Crystal Violet from Natural Seawater coupled with HighPerformance Liquid Chromatographic Determination

Molecularly imprinted polymers （MIPs） were prepared by the bulk polymerization using crystal violet as the template molecule, and the methacrylic acid and ethylene glycol dimetheacrylate as functional monomer and cross-linker, respectively. Sys- tematic investigations of synthetic conditions were conducted. The surface morphology and recognition mechanism of the obtained polymers were studied using scanning electron microscope and spectrophotometric analysis. MIPs showed high atTmity to template molecule and were successfully applied as special solid-phase extraction sorbent for selective extraction of crystal violet from natural seawater. An off-line molecularly imprinted solid-phase extraction （MISPE） method followed by high-performance liquid chroma- tography with diodearray detection for the analysis of crystal violet was also established. MISPE columns have good recoveries for crystal violet standard solutions and good linearity was obtained over the concentration range of 0-200 ~tg L-1 （R2 〉 0.99）. Finally, two natural seawater samples were investigated. The recoveries of spiked seawater on the MISPE columns were from 44.47% to 62.34%, the relative standard deviation （n=3） being in the range of 2.89%-5.96%.

Extraction-spectrophotometric Determination of Dicyanoaurate(Ⅰ) with Crystal Violet

Extraction spectrophotometric determination of dicyanoaurate (Ⅰ) with Crystal Violet is described. At pH 2.6～10.7, dicyanoaurate (Ⅰ) can react with Crystal Violet and form a complex which can be extracted into isoamylacetate. The apparent molar absorptivity is 8.37×10 4 L·mol -1 ·cm -1 at 605 nm. Beer′s law is obeyed for 0～15 μg of Au(Ⅰ) per 5 ml of isoamylacetate. The interference from Ag(Ⅰ) and Cu(Ⅱ) can be eliminated with thiourea and EDTA. The method is applied to the determination of dicyanoaurate (Ⅰ) in sample solution with satisfactory results.

Energy transfer in solid-state dye lasers based on methyl methacrylate co-doped with sulforhodamine B and crystal violet

Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG laser. Distributed feedback dye laser （DFDL） action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism. Theoretically, the characteristics of acceptor and donor DFDLs, and the dependence of their pulse widths and output powers on acceptor-donor concentrations and pump power, were studied. Experimentally, the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor-donor concentrations. Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium. The laser wavelength showed continuous tunability from 563 nm to 648 nm.

FRACTAL STRUCTURE OF COLLOIDAL SILVER AND ITS EFFECTS ON SERS INTENSITIES OF CRYSTAL VIOLET

The surface-enhanced Raman spectra (SERS) of crystal violet on colloidal silver particles of different sizes and shapes were measured and the structural effect of the silver aggregates on the SEPS intensities was discussed in terms of fractal geometry. It is found that the SERS band intensities of crystal violet change significantly with the fractal dimension (D) of colloidal silver at 1.25<D<1.65, but remains nearly constant at D>1.8.

Aminopropyl-containing ionic liquid based organosilica as a novel and efficient adsorbent for removal of crystal violet from wastewaters

Herein a novel aminopropyl-containing ionic liquid based organosilica(ILOS-NH_2) is prepared, characterized and applied as effective adsorbent for removal of crystal violet(CV) dye from wastewater. The ILOS-NH2 material was synthesized by hydrolysis and co-condensation of 1,3-bis-(3-trimethoxysilylpropyl)-imidazolium chloride(BTMSPIC) under acidic conditions followed by treatment with 3-aminopropyl-trimethoxysilane in toluene under reflux conditions. This material was characterized using scanning electron microscopy(SEM), diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS), thermal gravimetric analysis(TGA) and energy dispersive X-ray analysis(EDAX). The material was effectively used in the removal of crystal violet at ambient temperature and showed high capacity and stability under applied conditions. The efficacy of p H, contact time, adsorbent dose, initial dye concentration, temperature, and isotherm studies and the applicability of pseudo-first, second order and Elovich kinetic models have also been investigated.

Surface Enhanced Raman Scattering on Self-assembled Nano Silver Film Prepared by Electrolysis Method

We demonstrate surface enhanced Raman scattering （SERS） detection of self-assembled nano silver film using a low-cost electrolysis strategy at a proper voltage and silver nitrate concentration in electrolyte. The concentration dependence of SERS from crystal violet （CV） molecules adsorbed to silver film was systematically studied. Importantly, the SERS surface enhancement factor of such nano silver film was 603, which was measured by a portable Raman spectrometer. The minimum concentration of detectable CV molecules can be as low as 10^-11 mol/L. The nano silver film prepared by this electrolysis method is an active, stable, cost-effective, and reusable SERS substrate.

In vivo histological diagnosis for gastric cancer using endocytoscopy

AIM To examine usefulness of virtual biopsy using endocytoscopy by comparing the in vivo endocytoscopic and histopathological images of gastric cancers.METHODS Endocytoscopy was performed in 30 patients with early gastric cancer. Of these, 26 patients showed well differentiated adenocarcinomas, while 4 patients showed poorly differentiated adenocarcinomas(including one signet ring cell carcinoma). Cancerous and non-cancerous areas were observed after double staining with 0.05% crystal violet and 0.1% methylene blue. The endocytoscopic images obtained were evaluated by an expert endoscopist and an expert pathologist without knowledge of patient clinical data, and endocytoscopic and histopathological diagnoses were compared.RESULTS The endocytoscopic images of the cancerous area were assessed as evaluable in 25(83.3%) and 27(90%) patients by endoscopist A and pathologist B, respectively, and those of the non-cancerous area as evaluable in 28(93.3%) and 23(76.7%) patients by the endoscopist and pathologist, respectively. The sensitivity, specificity, and diagnostic accuracy of gastric cancer diagnosis using evaluable endocytoscopic images were 88.0% and 92.9%, and 90.6% by endoscopist A, and 88.9% and 91.3%, and 90.0% by pathologist B, respectively. Evaluation of the diagnostic concordance rate between the endoscopist and the pathologist by inter-observer agreement calculation revealed no significant difference between the two observers. The inter-observer agreement(κ-value) for endocytoscopic diagnosis was 0.745. CONCLUSION Endocytoscopy is useful for the differentiation of cancerous from non-cancerous gastric mucosa, making it a promising tool for virtual biopsy.

Quantitative and sensitive detection of prohibited fish drugs by surface-enhanced Raman scattering

Rapid and simple detections of two kinds of prohibited fish drugs, crystal violet （CV） and malachite green （MG）, were accomplished by surface-enhanced Raman scattering （SERS）. Based on the optimized Au/cicada wing, the detectable concentration of CV/MG can reach 10-7 M, and the linear logarithmic quantitative relationship curves between log/and logC allows for the determination of the unknown concentration of CV/MG solution. The detection of these two analytes in real environment was also achieved, demonstrating the application potential of SERS in the fast screening of the prohibited fish drugs, which is of great benefit for food safety and environmental monitoring.

Preparation, characterization and photocatalytic activity of N-doped TiO_2 nanocrystals

N-doped TiO2 nanocrystals were prepared using titanium alkoxide as precipitant with different proportional materials. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectra. It is confirmed experimentally that the photocatalytic activity of N-doped TiO2 is much higher than that of Degussa P25, when used for the degradation of crystal violet. The degradation kinetics follows an apparent first-order reaction, which is consistent with a generally observed Langmuir-Hinshelwood mechanism. The doping of TiO2 with nitrogen significantly increases the absorption in the region of visible light. The energy of the band gap of N-doped TiO2 is 2.92 eV. The better performance of N-doped TiO2 can be explained by the fact that it is also excited with longer-wavelength light.

Fabrication of SERS-Active Au@Au@Ag Double Shell Nanoparticles for Low-Abundance Pigment Detection

Au@Au@Ag double shell nanoparticles were fabricated and characterized using TEM,STEM-mapping and UV-Vis methods.Using crystal violet as Raman probe,the surface-enhanced Raman scattering(SERS)activity of the as-prepared Au@Au@Ag nanoparticles was studied by comparing to Au,Au@Ag and Au@Au core-shell nanoparticles which were prepared by the same methods.Moreover,it can be found that the SERS activity was enhanced obviously by introduction of NaCl and the concentrations of NaCl played a key role in SERS detection.With an appropriate concentration of NaCl,the limit of detection as low as 10^(-10)mol/L crystal violet can be achieved.The possible enhanced mechanism was also discussed.Furthermore,with simple sample pretreatment,the detection limit of 5μg/g Rhodamine B(RhB)in chili powders can be achieved.The results highlight the potential utility of Au@Au@Ag for detection of illegal food additives with low concentrations.

The Effect of Laser Irradiation on Surface Enhanced Raman Scattering for Silver Film

The laser irradiation effect on the SERS intensity for Ag film is discussed using crystal violet (CV) as a probe. The thickness of silver film,the etching time of the glass slide by gaseous hydrogen fluoride, and the laser irradiation time for different amounts of CV on silver films were investigated. The laser burn out model was proposed to explain the dependence of the SERS intensity of CV on the laser irradiation time.

Determination of Dimethylallylamine by Titration in Nonaqueous Solvent

The content of dimethylallylamine was determined using glacial acetic acid as solvent, acetic-formic mixture as an anhydrite, perchloric acid-glacial acetic acid as titrant, and 1% crystal violet in acetic acid as indicator in the presence of methylamine and dimethylamine The influences of inert constituents and water on the titration were investigated, and a complete analytical method was determined. The results showed that the determination error of total amines increased with water increasing, while the effect of water on the determination of dimethylallylamine was little when the amount of water was within 5%, the relative error was generally within 1%, and that the end-point was acutely when about 10% chloroform was added. Compared with gas chromatography, this method is simple, convenient and accurate.

Surface-enhanced fluorescence and application study based on Ag-wheat leaves

Wheat leaves with natural microstructures as substrates were covered by the silver nanoislands by magnetron to prepare a low-cost, environment-friendly and mass production surface-enhanced fluorescence(SEF) substrate(Ag-WL substrate). The best SEF substrate was selected by repeatly certifying the fluorescence intensity of 10^(-5)M Rhodamine B(RB) and 10^(-5)M Rhodamine 6G(R6G) aqueous solutions. The abundant semi-spherical protrusions and flake-like structures on the surface of the Ag-WL substrate produce high-density hot spots, which provides a new and simple idea for the preparation of biomimetic materials. The results of 3D finite-different time-domain(FDTD) simulation show that the nanoisland gap of semi-spherical protrusions and flake-like structures has produced rich hotspots. By adjusting the time of magnetron sputtering, the enhancement factor(EF) was as high as 839 times, relative standard deviation(RSD) reached as low as 10.7%, and the substrate was very stable and repeatable, which shows that Ag-WL substrate is trustworthy.Moreover, semi-spherical protrusions provide stronger surface-enhanced Raman scattering(SERS) effects compared to flake-like structure. What is more surprising is that the detection limit of the substrate for toxic substance crystal violet(CV) is as low as 10^(-10)M.

The Effect of Interleukin-6 on the Proliferation of Prostate Cancer Cells in Vitro and the Modulation of This Procedure

The role of interleukin-6 (IL-6) in the growth of an androgen-independent prostate cancer cell line (PC-3m) was defined and the effect of dexamethasone, which was previously shown to modulate IL-6/IL-6 receptor (IL-6R) on this procedure was investigated. By using a pretty sensitive and specific enzyme immunoassay (ELISA), it was found that PC-3m produced certain IL-6, but there was no difference in IL-6 secretion between the group with or without dexamethasone treatment. It was also found that PC-3m cells could not be stimulated to grow by exogenous IL-6 (P>0.05), while it could be inhibited to grow by anti-IL-6 monoclonal antibody and dexamethasone with a dose-dependent fashion. Our observation indicated that IL-6 acted as an autocrine growth factor for PC-3m, and dexamethasone could inhibit cell proliferation by a mechanism independent of its effect on IL-6 mRNA expression.

Grafting of Acrylamide and Trimethylolpropane Triglycidyl Ether onto the Gellan Gum:Synthesis and Characterization

To improve the physiochemical properties of gellan gum（GG）, GG was modified with acrylamide and trimethylolpropane triglycidyl ether（TTE）. The structure and morphology of modified GG were characterized by Fourier transform infrared（FT-IR） spectroscopy, X-ray diffraction（XRD）, differential scanning calorimetry（DSC） and scanning electron microscopy（SEM）. The characteristic peaks at 3448, 2788, 1654, 1411, 1117 and 1044 cm-1）in the FT-IR spectrum confirm the modification. The XRD and DSC data revealed that the modification enhanced the thermal stability of GG. SEM analysis suggested the modification introduced a porous microstructure, resulting in the adsorption of crystal violet. In addition, the adsorption capacity, thermal stability and swelling property of GGTTE3 were superior to GGTTE1, GGTTE2, GGTTE4 and GGTTE5.

Elimination of Cationic and Anionic Dyes by Natural Phosphate

The present work aims to study the adsorption, determining the ability of phosphate to remove cationic dyes, MB （methylene blue） and CV （crystal violet） and an anionic dye, the MO （methyl orange）. To explain the important reduction of pollution parameters obtained from its use as a filter bed. Natural phosphate is contacted with an aqueous solution having a concentration of 20 mg/L for 90, 45 and 20 min respectively for the MB, CV and MO. Experimental results show that the phosphate totally eliminates the CV and the WB. While, the adsorption of MO is very low. The Langmuir isotherm applies to MB and MO while the adsorption of CV uses the Freundlich isotherm.

Photo Degradation of Dyes from Their Aqueous Solutions of Their Binary Mixture, Using TiO2 as the Oxidant with Different Sources of Energy

The photodegradation has been widely used in water and waste water treatment of all the methods like froth flotation coagulation etc., photodegradation appears to offer the best prospects for overall treatment of dyestuff effulent. Photodegradation of aniline blue and crystal violet dyes from aqueous solutions of their binary mixture was carried out using TiO2 as photocatalyst. By carrying out photodegradation, varying the experimental parameters, the optimum conditions required for maximum degradation was found out. The photodegradation of dye was carried out using different sources of energy like solar radiation and microwave radiation. The degradation studies were carried out at temperatures 25 ℃, 35 ℃ and 45 ℃ so as to calculate the rate constant and activation parameters. Both energy sources are equivalent in causing degradation in all respects except time and dose of photo catalyst. Time required is less for microwave than solar radiation, but dose of photo catalyst needed was high for microwave radiation. These results will be helpful in designing effluent treatment plants in industries.

The Synthesis, Characterization, Photocatalytic Evaluation and Deactivation Behavior of Sheet-like Nano Titania

The sheet-like nano TiO2 particles were prepared by using hydrothermal method, and were characterized by X-ray diffraction（XRD）, infrared spectroscopy（IR）, and transmission electron microscopy （TEM）. It is found that the nanoparticle sizes and crystallinity increase with the increase of hydrothermal temperature from 150 ℃ to 160 ℃, and then to 180 ℃. With the increase of particle sizes, the absorption capacities and photocatalytic abilities of as-prepared TiO2 particles for crystal violet become better and better. The nano TiO2 with big particles is more stable than that with small particles, although its initial photocatalytic activity is relatively lower compared with that of the small particle samples.