A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermarks. In this work, Au NCs were "grown" both inside and on the surface of BSA/MMT clay using one-step reduction of HAu Cl4 by BSA. The as-prepared Au NC-BSA/MMT nanocomposites emit intensive red fluorescence under the excitation of UV-visible light and show stable chemical features and low toxicity. The obtained fluorescent powders were characterized by UV-visible absorption spectroscopy,fluorescence spectroscopy, infrared spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction to depict their sizes, structural information and optical features. Given their environmentally friendly preparation, simple operation, low cost, efficient UVvisible radiation-dependent photoluminescence and good affinity with finger residues, the in situ synthesized Au NC-BSA/MMT nanocomposite powders were used as an alternative fluorescent developing reagent for developing latent fingermarks deposited on various object surfaces(such as glass, aluminum foil, painted metal, plastic products and weighing papers) for individual identification. As results, the developed fingermarks with clear patterns and satisfactory level-2(minutiae points) and level-3(sweat pores) ridge details were obtained. Notably, treated prints could be excited by red light and emitted near infrared fluorescence, which was beneficial to avoid background interference and reduce the damage caused by UV light. With the advantages of the simple preparation process and good enhancement performance for latent fingermarks, the proposed method might be used in the preparation of various fluorescent probes for detecting trace evidence in forensic sciences. 相似文献
Preparation method of polyaniline/montmorillonite (PANI/MMT) nanocomposite in the form of thin layer deposited on various substrates is optimized in this work to obtain high electrical conductivity. Simple method (i.e. polymerization of anilinium sulfate in the presence of MMT) has been used for the preparation and following four conditions were varied: preparation temperature (T = 10 or 20 °C), preparation time (t = 4 or 6 h), size fraction of MMT (p < 1 or 5 µm), and type of substrate (microscope glass slides, silica glass slides, polyester foils). Therefore, 24 samples were prepared, characterized and their electrical conductivity was compared. Raman spectroscopy and scanning electron microscopy were used for the characterization of the structure of samples. Thickness of layers was measured using atomic force microscopy. Based on the comparison of samples and with respect to the aim of obtaining high electrical conductivity, it was found that the most suitable substrate is polyester foil and preparation conditions are T = 20 °C, t = 6 h, p < 5 µm. To obtain highly conductive layers on glass substrates (although less conductive than layers on foil), preparation time have to be shortened to 4 h. 相似文献
High strength cellulose composite films with antibacterial activities were prepared by dispersing montmorillonites (MMT) into cellulose solution in LiOH/urea aqueous solvent followed by regeneration in ethanol coagulation bath, and then by soaking in 5 wt% hexadecylpyridine bromide ethanol solutions to induce the antibacterial action. The cellulose/MMT composite films were characterized by field emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, FTIR, UV-spectra, wide angle X-ray diffraction and mechanical test. The results revealed that MMT was dispersed well in the cellulose matrix to form layer structure with a thickness of approximately 3 nm. The mechanical properties of the cellulose/MMT composite films were significantly improved to achieve 132 MP for tensile strength as a result of the MMT delamination. The hexadecylpyridine bromide was fixed well in the cellulose/MMT matrix through cation exchange, leading to the excellent antibacterial activities against Staphylococcus aureus and Escherichia coli, which is important in their practical applications. 相似文献
The target of the present investigation is synthesis and characterization of an amphiphilic diblock copolymer with antibacterial property. Ring opening polymerization (ROP) of ε-caprolactone (CL) and tetrahydrofuran (THF) was carried out under inert atmosphere by using L-cysteine as a bridging agent in the presence of stannous octoate (SO) as a catalyst. The nano silver end capped diblock copolymer was synthesized by in situ method. Thus obtained nano silver end capped L-cysteine bridged diblock copolymer was characterized by various analytical methods like Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD), fluorescence spectroscopy, gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and zeta potential. The antimicrobial property of the nano silver end capped diblock copolymer against e-coli was tested. 相似文献
In this paper, the interaction between herbacetin and BSA was investigated by fluorescence and three-dimensional fluorescence spectroscopy under simulated physiological conditions. It was proved that the fluorescence quenching of BSA by herbacetin was mainly the result of the formation of a herbacetin–BSA complex. The modified Stern–Volmer quenching constant and the corresponding thermodynamic parameters ΔH0, ΔG0 and ΔS0 were calculated at different temperatures. The results indicated that electrostatic interactions were the predominant intermolecular forces in stabilizing the complex. The distance r=3.23 nm between the donor (BSA) and acceptor (herbacetin) was obtained according to Förster’s nonradioactive energy transfer theory. The synchronous fluorescence and three-dimensional fluorescence spectra results showed that the hydrophobity of amino acid residues increased in the presence of herbacetin. These results revealed that the microenvironment and conformation of BSA changed during the binding reaction. 相似文献
Gold nanoclusters (AuNCs) protected with a bovine serum albumin (BSA) coating are known to emit red fluorescence (peaking at 650 nm) on photoexcitation with ultraviolet light (365 nm). On addition of Cu(II) ions, fluorescence is quenched because Cu(II) complexes certain amino acid units in the BSA chain. Fluorescence is, however, restored if pyrophosphate (PPi) is added because it will chelate Cu(II) and remove it from the BSA coating on the AuNCs. Because PPi is involved in the function of telomerase, the BSA@AuNCs loaded with Cu(II) can act as a fluorescent probe for determination of the activity of telomerase. A fluorescent assay was worked out for telomerase that is highly sensitive and has a wide linear range (10 nU to 10 fM per mL). The fluorescent probe was applied to the determination of telomerase activity in cervix carcinoma cells via imaging. It is shown that tumor cells can be well distinguished from normal cells by monitoring the differences in intracellular telomerase activity.
Graphical abstract Gold nanoclusters (AuNCs) protected by bovine serum albumin (BSA) and displaying red photoluminescence were prepared as fluorescent probe for the determination of telomerase activity and used for imaging of cervix carcinoma (HeLa) cells.
The mechanism of binding of vitamin C (VC) with bovine serum albumin (BSA) was investigated by spectroscopic methods under simulated physiological conditions. VC effectively quenched the intrinsic fluorescence of BSA. The binding constants KA, and the number of binding sites, n, and corresponding thermodynamic parameters ΔGΘ, ΔHΘ and ΔSΘ between VC and BSA were calculated at different temperatures. The primary binding pattern between VC and BSA was interpreted as being a hydrophobic interaction. The interaction between VC and BSA occurs through static quenching and the effect of VC on the conformation of BSA was also analyzed using synchronous fluorescence spectroscopy. The average binding distance, r, between the donor (BSA) and acceptor (VC) was determined based on Förster’s theory and was found to be 3.65 nm. The effects of common ions on the binding constant of VC-BSA were also examined. 相似文献
A colloidal solution of gold nanoparticles is synthesized with the use of sodium tetrachloroaurate(III) as a precursor, oleylamine as a reducer and surfactant, and 1-octadecene as a solvent. Reaction stages are analyzed in situ by optical (UV-vis) absorption spectroscopy with a simultaneous analysis of particle sizes by dynamic light scattering and X-ray absorption near edge spectroscopy for the analysis of the gold oxidation state. After the synthesis the size of obtained nanoparticles is determined by transmission electron microscopy. The analysis of the obtained experimental data reveals the presence of three main steps in the reduction reaction mechanism, corresponding to Au3+, Au+, Au0, which enables the construction of the reaction model. The reaction mechanism involves the formation of gold(I) complexes with oleylamine, followed by polymerization and the formation of gold nanoclusters coated with oleylamine. 相似文献
In the current work, novel environmentally friendly water-soluble fluorescent carbon dots coated with chitosan (CDs/CTS) were successively synthesized via a facile and green preparation procedure. The fluorescent carbon dots were prepared through a simple, convenient and one-step hydrothermal method in the presence of cellulose as a raw material. The CDs/CTS were connected together via intermolecular hydrogen bonds interaction and chemical bonds between hydroxyl and amino groups in the chitosan polymeric chains and hydroxyl groups of fluorescent carbon dots. This approach can be applied for milligram-scale preparation of these water-soluble particles. The CDs/CTS material showed blue fluorescence under UV exposure. The structure and morphology of as-prepared CDs/CTS were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The as-prepared CDs/CTS exhibited excellent fluorescent property and good stability. The fluorescence of as-prepared CDs/CTS could be quenched by the Cr(VI) ions. The effects of environmental factors on the fluorescence intensity were investigated in detail, and the obtained results showed that the optimum conditions for the Cr(VI) ions determination were as follows: 1:3 of mass ratio of CDs/CTS, 9.5 of pH and 20 min of reaction time. Under optimized experimental conditions, a novel fluorescent probe was developed for the detection of Cr(VI) ions, which exhibited wide linear ranges (0–600 μmol/L) and excellent selectivity. The proposed method was directly applied for the determination of Cr(VI) ions in water and soil samples with satisfactory results. 相似文献
A metastable form of 9-fluorenone (MS9F) has been characterized using Raman spectroscopy, fluorimetry, and X-ray diffraction techniques. MS9F emits blue fluorescence (λmax=495 nm) upon 365 nm irradiation and undergoes a single-crystal-to-single-crystal (SCSC) transformation to reach the ground state form (GS9F) over approximately 30 minutes, whereupon it emits the expected green fluorescence. A structure–property relationship for this fluorescent behavior has been posited. MS9F and GS9F were applied as a means of visualizing latent fingermarks on a nonporous surface. This approach identified three different modes of fluorescent fingermark visualization using 9-fluorenone. 相似文献
In order to verify the anti-UV aging mechanism about polypropylene-grafting-acrylonitrile (PP-g-AN) to polypropylene (PP), the structural analysis of the PP/PP-g-AN blend before and after aging was carried out via the X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectrometry (FTIR) and UV-visible Absorbance Spectrum (UV–Vis). Inference on PP-g-AN anti-aging process was proposed and confirmed. 相似文献
A selective fluorescent chemosensor was prepared by anchoring pyridine-2-carbaldehyde Schiff base ligand onto mesochannels of organically modified SBA-15 mesoporous silica. The resulting organic-inorganic hybrid mesoporous chemosensor was characterized by X-ray diffraction, Fourier transform IR spectroscopy, transmission electron microscopy, UV-visible diffuse reflectance spectra, and photoluminescence spectra. All the results support the idea that successive attachment of the ligand moiety onto one-pot-modified mesoporous scaffold has not altered its basic hexagonally arranged structure. Upon introducing trace amounts of zinc ions into aqueous solution, remarkable enhancement in the fluorescence was observed. 相似文献
通过共沉淀法合成了发红色荧光的类水滑石材料,采用硅烷偶联剂对其进行了表面改性,并利用荧光光谱、红外光谱、X射线衍射(XRD)和扫描电子显微镜(SEM)等对其结构和性能进行了表征,探讨了表面改性对荧光类水滑石的影响.将改性荧光类水滑石与发射波长为384 nm的In Ga N芯片组合制成发光二极管,器件发出明亮的红光.研究结果表明,改性的发红色荧光的类水滑石是制作白光二极管可供选用的红色发光材料. 相似文献