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Electrochemiluminescence of gold nanoparticles and gold nanoparticle-labelled antibodies as co-reactants
摘要： Gold nanoparticles (AuNPs) and AuNP-labelled antibodies can participate in the electrochemiluminescence (ECL) reaction of tris(2,20-bipyridyl) ruthenium(II) (Ru(bpy)3 2+) as a co-reactant. The electrochemical and spectral characteristics of this new ECL system were con?rmed by experiments, and its reaction mechanism was speculated to be di?erent from that of typical ECL. The experimental results showed that the new ECL system exhibited higher ECL e?ciency, and AuNP-labelled substances can be sensitively measured with the help of AuNPs. Based on the dual role of AuNPs as a co-reactant and marker, the AuNP–Ru(bpy)3 2+ ECL system will be a useful tool in biochemical analysis.
关键词： co-reactant,Ru(bpy)3 2+,Electrochemiluminescence,biochemical analysis,gold nanoparticles
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Localized Surface Plasmon Resonance Based Tapered Fiber Optic Ethanol Sensor
摘要： Ethanol is mostly found in drinks, food, beverages and in the human body fluids, e.g. urine, serum, sweat, saliva, and blood etc. A high concentration of ethanol in body fluids causes various metabolic disorders like diabetes, cirrhosis and hepatitis. Therefore, the detection of ethanol is essential for clinical and forensic investigation. In this study, we report the fabrication and characterization of a localized surface plasmon resonance (LSPR) based tapered fiber optic ethanol sensor. Nowadays LSPR is a very useful technique for biosensing applications. For the LSPR phenomenon, the size of the nanoparticles should be smaller than the wavelength of the light. When an electromagnetic wave is incident on metal nanoparticles, the collective oscillation of the free electrons inside the metal nanoparticles occurs. The maximum amplitude occurs when the frequency of oscillation matches with the frequency of the incident light. Due to the frequency matching a strong field enhancement is observed around the nanoparticles. In the phenomenon called as LSPR, the peak absorbance wavelength depends on the dielectric constant of the medium surrounding the nanoparticles. To fabricate the LSPR based fiber optic probe for ethanol sensing, we have synthesized gold nanoparticles (AuNP) using Turkevich method. The TEM image of AuNPs is shown in fig. 1 (a). The schematic of the LSPR probe is shown in fig 1 (b). The probe is consists of AuNPs over the core of the tapered optical fiber followed by the immobilized layer of enzyme alcohol dehydrogenase (ADH) and coenzyme nicotinamide adenine dinucleotide (NAD). For the attachment of gold nanoparticles the core was cleaned by pirhana solution and kept in amino silane solution. Dip coating was used to coat the AuNPs over the silanized core. After this, the probe was incubated in 1 mM aqueous solution of cystamine dihydrochloride for 1 h for attachment of –NH2 groups over the AuNPs-coated fiber core. Finally, the probe was incubated for 12 h into the ADH and NAD solution. This completed the probe fabrication step.
关键词： Ethanol Sensor,Alcohol Dehydrogenase,Tapered Fiber Optic,Localized Surface Plasmon Resonance,Nicotinamide Adenine Dinucleotide,Gold Nanoparticles
更新于2025-09-11 14:15:04
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Effect of High Pressure in the Luminescence of Pr <sup>3+</sup> Doped Ge <sub/>2</sub> O- PbO Glass Containing Au Nanoparticles
摘要： In this paper it was investigated the combined effect of gold nanoparticles and high-pressure densification on the luminescence of Pr3+ doped heavy metal GeO2-PbO photonic glass. Localized states related to ion-trapped exciton defects, S1 and S2, were observed at 342 and 412 nm before densification. After densification under 7.7 GPa the structure of the glass host changed irreversibly, as indicated by the infrared spectrum, refractive index and density measurements. TEM analyses indicated that the high-pressure densification induced the formation of clusters of gold nanoparticles. The modifications observed in the absorption and luminescence spectra of Pr3+ ions in the VIS-NIR range were associated to the changes in the local field surrounding the Pr3+ ions in the host glass induced by high-pressure. For excitation at 445 nm (luminescence from 3P2) and 593 nm (luminescence from 1D2), the combined effect of densification and gold nanoparticles induced an increase in the emission band at 1050 cm-1. For excitation at 488 nm (luminescence from 3P0), the combined effect resulted in a strong decrease in the emission intensities in the VIS, revealing the emergence of non-radiative processes in resonance with 3P0 state. The observed behavior was probably due to energy transfer, ion trapped exciton defects and cross-relaxation processes among the Pr3+ ions and gold nanoparticles.
关键词： cross-relaxation processes,gold nanoparticles,Pr3+ doped,high-pressure densification,energy transfer,GeO2-PbO glass,luminescence
更新于2025-09-11 14:15:04
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Gold nanoparticles as a potent radiosensitizer in neutron therapy
摘要： The purpose of this study was to investigate the potential of gold nanoparticles as radiosensitizer for use in neutron therapy against hepatocellular carcinoma. The hepatocellular carcinoma cells lines Huh7 and HepG2 were irradiated with γ and neutron radiation in the presence or absence of gold nanoparticles. Effects were evaluated by transmission electron microscopy, cell survival, cell cycle, DNA damage, migration, and invasiveness. Gold nanoparticles significantly enhanced the radiosensitivity of Huh7 and HepG2 cells to γ-rays by 1.41- and 1.16-fold, respectively, and by 1.80- and 1.35-fold to neutron radiation, which has high linear energy transfer. Accordingly, exposure to neutron radiation in the presence of gold nanoparticles induced cell cycle arrest, DNA damage, and cell death to a significantly higher extent, and suppressed cell migration and invasiveness more robustly. These effects are presumably due to the ability of gold nanoparticles to amplify the effective dose from neutron radiation more efficiently. The data suggest that gold nanoparticles may be clinically useful in combination therapy against hepatocellular carcinoma by enhancing the toxicity of radiation with high linear energy transfer.
关键词： neutron therapy,cancer,radiosensitizer,γ-ray,gold nanoparticles
更新于2025-09-11 14:15:04
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Low-blinking SERS substrate for switchable detection of kanamycin
摘要： Metallic plasmonic nanoparticles generate surface-enhanced Raman Scattering (SERS) for wide sensing applications of biomolecules, gas and environmental contaminants. However, the metallic materials cause high thermal radiation during laser excitation in the opto-microfluidic systems and give rise to temporal intensity fluctuations, which is called blinking effects in SERS spectra. This work developed nanocomposite consisting of graphene oxide (GO) and gold nanoparticles (AuNPs) with high thermal stability and low thermal radiation, which provided plasmonic resonance while reduced blinking effect for SERS-based sensing in the microfluidic detection system. The system was applied to detect kanamycin in drinking water, orange juice, and milk by using Texas Red-dye conjugated Beacon aptamer, where the aptamer was designed to be specific and switchable in kanamycin recognition. The sensor was reusable, and its limit of detection was 0.75 nM in a linear range of 1 nM to 100 nM. The microfluidic SERS detection system can be potentially used for sensitive and reliable assays of small molecules.
关键词： Graphene oxide,Gold nanoparticles,SERS,Blinking effects,Antibiotic sensor
更新于2025-09-10 09:29:36
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Influence of size and surface capping on photoluminescence and cytotoxicity of gold nanoparticles
摘要： Hydrophilic and homogeneous sub-10 nm blue light-emitting gold nanoparticles (NPs) functionalized with different capping agents have been prepared by simple chemical routes. Structure, average, size, and surface characteristics of these NPs have been widely studied, and the stability of colloidal NP solutions at different pH values has been evaluated. Au NPs show blue PL emission, particularly in the GSH capped NPs, in which the thiol-metal core transference transitions considerably enhance the fluorescent emission. The influence of capping agent and NP size on cytotoxicity and on the fluorescent emission are analyzed and discussed in order to obtain Au NPs with suitable features for biomedical applications. Cytotoxicity of different types of gold NPs has been determined using NPs at high concentrations in both tumor cell lines and primary cells. All NPs used show high biocompatibility with low cytotoxicity even at high concentration, while Au-GSH NPs decrease viability and proliferation of both a tumor cell line and primary lymphocytes.
关键词： Semiconfocal microscopy,Photoluminescence,Capping,Cell viability,GSH,Gold nanoparticles,Agent,Proliferation,Cytotoxicity
更新于2025-09-10 09:29:36
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Reusable fiber taper sensor based on the metastability of gold nanoparticles
摘要： This work presents the design and implementation of a reusable-tapered optical fiber sensor (RFS). We used the RFS together with a white light source to analyze the metastability of gold nanoparticles. With the RFS we observed that reaction limited aggregation occurred when modifying the concentration of metastable gold nanoparticles (MAuNPs). This was detected by a red-shift and a broadening of the absorption band. The transition from a metastable to a stable state, regardless of the concentration of the MAuNPs, was achieved by the addition of glucose. The changes in the refractive index of the solution due to the presence of glucose and the stability of the MAuNPs were successfully detected by the RFS. Diffusion limited aggregation of the MAuNPs was rapidly triggered after the addition of insulin. Finally, to gain a better understanding of our results we used Raman spectroscopy together with a hollow core photonic crystal optical fiber (HC-PCF) and studied the chemical interactions between the MAuNPs and glucose and between the MAuNPs and insulin.
关键词： glucose,Raman spectroscopy,metastable gold nanoparticles,reusable-tapered optical fiber sensor,insulin
更新于2025-09-10 09:29:36
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Robust and accurate measurements of gold nanoparticle concentrations using UV-visible spectrophotometry
摘要： This paper provides an empirical formula to calculate the extinction efficiencies of gold nanoparticles over the size range 1–1000 nm in fluids with refractive indexes which extend from n = 1 to n = 1.62. The formula contains a shape factor to account for nonspherical particles and aggregates. The empirical curves are fitted to values calculated from accurate Mie and T-Matrix theory and confirm previous descriptions which are restricted to nearly spherical particles in water of diameter between 5 and 100 nm. This paper demonstrates that these previous descriptions will be in error for fluids other than water and for nonspherical particles greater than 100 nm in size. An empirical description is provided which matches calculated values to within a few percent across most of the range. The description also matches experimental data to within the standard relative error, currently 5% at best, using other methods which directly measure the particle concentration. These extinction efficiencies can be used to validate the concentration of gold nanoparticles in a wide range of situations to support the drive for reproducibility in nanoparticle research.
关键词： Mie theory,extinction efficiencies,gold nanoparticles,T-Matrix theory,UV-visible spectrophotometry
更新于2025-09-10 09:29:36
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Gold/WS2 nanocomposites fabricated by in-situ ultrasonication and assembling for photoelectrochemical immunosensing of carcinoembryonic antigen
摘要： Tungsten disulfide (WS2) nanosheets were obtained by exfoliating WS2 bulk crystals in N-methylpyrrolidone by ultrasonication. Gold nanoparticles (GNPs) were synthesized by in-situ ultrasonication of sodium citrate and HAuCl4 while fabricating the WS2 nanosheets. In this way, the GNPs were self-assembled on WS2 nanosheets to form a GNPs/WS2 nanocomposite through interaction between sulfur and gold atoms. The photoelectrochemical response of WS2 nanosheets is significantly enhanced after integration of the GNPs. The GNPs/WS2 nanocomposite was coated onto a glassy carbon electrode (GCE) to construct a sensing interface which then was modified with an antibody against the carcinoembryonic antigen (CEA) to obtain a photoelectrochemical immunosensor for CEA. Under optimized conditions, the decline in relative photocurrent is linearly related to the logarithm of the CEA concentration in the range from 0.001 to 40 ng mL?1. The detection limit is 0.5 pg mL?1 (at S/N = 3). The assay is sensitive, selective, stable and reproducible. It was applied to the determination of CEA in clinical serum samples.
关键词： Gold nanoparticles,CEA,Photoelectrochemistry,Nanosheets,Transition metal dichalcogenides,Immunosensor
更新于2025-09-10 09:29:36
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Detection of gold nanorods uptake by macrophages using scattering analyses combined with diffusion reflection measurements as a potential tool for in vivo atherosclerosis tracking
摘要： In this study, we report a potential noninvasive technique for the detection of vulnerable plaques using scatter analyses with flow cytometry (FCM) method combined with the diffusion reflection (DR) method. The atherosclerotic plaques are commonly divided into two major categories: stable and vulnerable. The vulnerable plaques are rich with inflammatory cells, mostly macrophages (MΦ), which release enzymes that break down collagen in the cap. The detection method is based on uptake of gold nanorods (GNR) by MΦ. The GNR have unique optical properties that enable their detection using the FCM method, based on their scattering properties, and using the DR method, based on their unique absorption properties. This work demonstrates that after GNR labeling of MΦ, 1) the FCM scatter values increased up to 3.7-fold with arbitrary intensity values increasing from 1,110 to 4,100 and 2) the DR slope changed from an average slope of 0.196 (MΦ only) to an average slope of 0.827 (MΦ labeled with GNR) (P0.001 for both cases). The combination of FCM and DR measurements provides a potential novel, highly sensitive, and noninvasive method for the identification of atherosclerotic vulnerable plaques, aimed to develop a potential tool for in vivo tracking.
关键词： flow cytometry,macrophages,gold nanoparticles,vulnerable plaques,noninvasive detection
更新于2025-09-10 09:29:36