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Tensile control of the thermal flow in plasmonic heaters realized on flexible substrates
摘要： In this paper, we present a simple and robust numerical method capable of predicting, with high accuracy, the thermal effects occurring for different gold nanoparticle arrangements under externally applied strain. The physical system is numerically implemented in the COMSOL Multiphysics simulation platform. The photothermal response of different arrangements of gold nanoparticles, resonantly excited by linearly polarized light, is considered with the system at rest and under the action of mechanical stress. The generation of heat at the nanoscale is analyzed by considering how this is affected by the variation of the extinction cross section. We describe the peculiar conditions under which mechanically controlled gold nanoparticle arrangements can significantly increase the local temperature due to the formation of localized photothermal hot spots. The resulting systems are envisioned in applications as optomechanically tunable plasmonic heaters.
关键词： COMSOL Multiphysics,photothermal effects,mechanical stress,plasmonic heaters,gold nanoparticles
更新于2025-09-12 10:27:22
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Synthesis of plasmonic gold nanoparticles supported on morphology-controlled TiO2 for aerobic alcohol oxidation
摘要： In the present research study, we report the synthesis of nano-sized gold (Au) particles immobilized on TiO2 support material. The morphologies of TiO2 support material was tailored and tuned to be rod, tube and microporous materials. The effect of plasmonic gold nanoparticles (NPs) deposited on different morphologies of TiO2 was studied. The prepared catalysts were characterized by various characterization techniques in order to have a detailed insight on the textural properties, morphology and electronic state of the material via UV–vis spectroscopy, N2 physisorption analysis, Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). We tested the controlled oxidation of benzyl alcohol to benzaldehyde using molecular oxygen at 373 K under atmospheric pressure. The results obtained from the thermal reaction conditions were compared with those performed under visible light irradiation (λ > 420 nm) at 373 K. Among all, Au/TiO2 nanorod catalyst displayed the superior performance of 33% yield in the absence of light and 55% yield of benzaldehyde with an external quantum efficiency of 3.4% under visible light irradiation (λ ≥ 420 nm) at 373 K for 4 h. The enhanced catalytic performances were attributed to the Au-LSPR phenomenon and a plausible reaction pathway has been discussed involving the generation of hot electrons during the course of reaction.
关键词： TiO2,Plasmonic catalysis and controlled oxidation,Gold nanoparticles
更新于2025-09-12 10:27:22
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Self‐Assembled Polyamidoamine Dendrimer on Poly (methyl meth‐ acrylate) for Plasmonic Fiber Optic Sensors
摘要： We report a novel one-step polyamidoamine (PAMAM) dendrimer based polymethyl methacrylate (PMMA) surface functionalization strategy for the development of polymeric optical (POF) based plasmonic sensors utilizing gold nanoparticles (AuNP). Simple contact angle measurements over PMMA sheets reveal the ability of the dendrimers to strongly bind to PMMA surface without additional acid/alkali pretreatment, unlike the conventional hexamethylene diamine (HMDA) based surface modification. Subsequently, U-bent POF probes with high evanescent wave absorbance sensitivity were exploited for relative quantification of the surface amine groups using fluorescein isothiocyanate (FITC) binding and efficient chemisorption of gold nanoparticles (AuNP) in order to identify the optimum conditions viz. dendrimer concentration, incubation time and dendrimer generation. While FITC binding showed a proportional increase in amine functional density with PAMAM concentration and time, interestingly the AuNP (40 nm) binding studies revealed the formation of loose PAMAM multilayers and their desorption. PAMAM (G4) concentration as low as 5 mM and incubation time of 24 h provide faster binding rate with densely packed AuNP and the RI sensitivity of ~ 15 (A546 nm/RIU). This simpler and inexpensive strategy could also be exploited for the development of functional PMMA substrates for various applications including nanotechnology, bio-imaging, drug delivery and analytical separations.
关键词： gold nanoparticles (AuNP),dendrimers,plasmonic sensors,polymethyl methacrylate (PMMA),polymeric optical fibers (POF),evanescent wave absorbance
更新于2025-09-11 14:15:04
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In vivo evaluation of safety, biodistribution and pharmacokinetics of laser-synthesized gold nanoparticles
摘要： Capable of generating plasmonic and other effects, gold nanostructures can offer a variety of diagnostic and therapy functionalities for biomedical applications, but conventional chemically-synthesized Au nanomaterials cannot always match stringent requirements for toxicity levels and surface conditioning. Laser-synthesized Au nanoparticles (Aunp) present a viable alternative to chemical counterparts and can offer exceptional purity (no trace of contaminants) and unusual surface chemistry making possible direct conjugation with biocompatible polymers (dextran, polyethylene glycol). this work presents the first pharmacokinetics, biodistribution and safety study of laser-ablated dextran-coated Aunp (Aunpd) under intravenous administration in small animal model. our data show that Aunpd are rapidly eliminated from the blood circulation and accumulated preferentially in liver and spleen, without inducing liver or kidney toxicity, as confirmed by the plasmatic ALAT and ASAT activities, and creatininemia values. Despite certain residual accumulation in tissues, we did not detect any sign of histological damage or inflammation in tissues, while IL-6 level confirmed the absence of any chronic inflammation. The safety of AuNPd was confirmed by healthy behavior of animals and the absence of acute and chronic toxicities in liver, spleen and kidneys. our results demonstrate that laser-synthesized Aunp are safe for biological systems, which promises their successful biomedical applications.
关键词： gold nanoparticles,biodistribution,pharmacokinetics,toxicity,laser ablation
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) - Plasmonic Heating of Gold Nanoparticles for Controlling of Current across Lipid Membranes in Modulating Neuronal Behavior Applications
摘要： Electrophysiology is a golden method for the study of the nervous system. However, electrical stimulation has to deal with multiple challenges, including selectivity, spatial resolution, mechanical stability, and implant-induced injury. Optical stimulation techniques may avoid some of these challenges by providing more selective stimulation, higher spatial resolution and reduced invasiveness of the device. Optogenetics is a technique to introduce light-sensitive ion channels to neurons for optical stimulating of them with tight spatial and temporal confinement. While optogenetics provides a powerful tool for studying neural functions, the main limitation for clinical applications is gen expiration. One current status of the optical stimulation technique is using nanoparticles (NPs) for temperature manipulation of neural cells at the nanoscale. Nanoabsorbers like gold nanoparticles (AuNPs) when irradiated at their plasmon resonance, AuNPs heat up rapidly and confer this heat to the plasma membrane. Laser irradiation of light-absorbing AuNPs transiently increases cell membrane permeability [1]. Here, we present an investigation of the interaction patterns of AuNPs with diameters from 10 and 50 nm with artificial membranes which local plasmonic heating of AuNPs can be utilized to regulate membrane currents and conductance situations of membranes. In this study, the black lipid membrane (BLM) as an artificial planar lipid membranes were used. BLM experiments were accomplished using a small Teflon chamber with two compartments (cis and trans) are separated by a small aperture onto which the lipid bilayer membrane is formed. The compartments are each filled with a different concentration of KCl as an electrolyte solution. The membrane current (I) was measured through silver/silver-chloride electrodes inserted into the aqueous salt solutions on both sides of the membrane, using a current-to-voltage converter[2]. To study the effects of NPs with different sizes on the cell membranes, the diphytanoyl-phosphatidylcholine (DiphPC) lipid were selected as bilayer membranes. AuNPs with different sizes and concentrations were always added to the cis-side of the membrane. AuNPs were plunged into the solution after a short time a laser with a wavelength of λ = 532 nm was focused on the hole. The laser power for all experiment was set to be 50 mW. In our experiments, light sources consist of both continuous and pulse irradiations. The obtained results show the amount of current that ?ows through a bilayer membrane was 17 and 10 pA for a continuous and pulse irradiation to the NPs with size 50 nm, respectively. While in the same experimental conditions heating of NPs with the size 10 nm leads to the current pass of membrane equal to 12 and 8pA, respectively.
关键词： Lipid Membranes,Neuronal Behavior,Plasmonic Heating,Optical Stimulation,Gold Nanoparticles
更新于2025-09-11 14:15:04
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Determination of Dopamine by a Label-Free Fluorescent Aptasensor Based on AuNPs and Carbon Quantum Dots
摘要： In order to reduce the complex modification process and obtain a fast and label-free aptasensor, a label-free fluorescent aptasensor based on gold nanoparticles (AuNPs) and carbon quantum dots (CQDs) was constructed for rapid determination of dopamine (DA). In the absence of DA, CQDs were adsorbed on the surface of AuNPs through the electrostatic force between CQDs and aptamer, which led to the fluorescence quenching of CQDs. When DA were added, they combined with the corresponding aptamers with higher affinity and selectivity, resulting in CQDs far from the surface of AuNPs and thus the fluorescence intensity of CQDs was recovered. Under the optimal condition, the fluorescence intensity of the released CQDs was linearly proportional to the concentration of DA in a range of 5×10-8~2.5×10-4mol/L with a detection limit of 1×10-8mol/L. Moreover, the aptasensor exhibited a satisfactory detection result of DA in human serum samples. This study provided a more effective method to detect a broad range of targets by using appropriate aptamers, holding great potential in the field of food safety and biomedical diagnostics.
关键词： Label-free,Gold nanoparticles,Fluorescent aptasensor,Carbon quantum dots
更新于2025-09-11 14:15:04
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Triplet Excited State Enhancement Induced by PDDA Polymer Assembled Gold Nanoparticles
摘要： Gold nanoparticles (AuNPs) have unique optical properties due to their characteristic localized surface plasmon resonances (LSPR). Upon the excitation of LSPR, AuNPs can affect the adjacent organic molecules strongly in both the ground state and the excited state. Previously, only 2~3 fold of plasmon enhancement effect on triplet state formation was displayed due to the random and uncontrollable formation of AuNP aggregates. Here, we utilize polymer PDDA to assemble AuNPs forming aggregates with strong plasmonic resonance. By means of transient UV-visible absorption spectroscopy, the triplet state of rose bengal enhanced by PDDA-AuNPs is directly monitored and the maximum enhancement is found to be ~ 10 fold. The large enhancement should be mainly resulted from the plasmon effect of AuNPs aggregates. Additionally, it is found that the triplet state enhancement effect of PDDA assembled AuNPs is sensitive to concentration of polymer and the size of AuNPs. These findings shed light on the applications of gold nanoparticles in triplet-triplet energy transfer, triplet exciton harvesting and photodynamic therapy.
关键词： PDDA polymer,Gold nanoparticles,Plasmon enhancement,Triplet excited state,Photodynamic therapy
更新于2025-09-11 14:15:04
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A study of the influence of plasmonic resonance of gold nanoparticle doped PEDOT: PSS on the performance of organic solar cells based on CuPc/C60
摘要： This work studied the role of gold nanoparticles (AuNPs) with different spherical sizes mixed with poly (3, 4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) as a hole transfer layer to enhance the efficiency (ITO/PEDOT:PSS (AuNPs)/CuPc/C60/Al) organic photovoltaic cell (OPV). AuNPs were synthesized using the thermochemical method and the results of the transmission electron microscope (TEM) images showed that the gold nanoparticles mostly dominated by spherical shapes and sizes were calculated in the range (12–23 nm). Measurements of UV-VIS spectra for AuNPs have shown that the surface plasmon resonance shifted to a higher wavelength with decreasing the particle size. Surface morphology and absorption spectra of OPV cells were studied using atomic force microscope and UV-VIS spectrometer techniques. The efficiency of the OPV cell was calculated without and with AuNPs. Efficiency was increased from 0.78% to 1.02% due to the embedded of AuNPs with (12 nm) in PEDOT/PSS. The increase in the light absorption in CuPc is due to the good transparent conducting of PEDOT:PSS and the increase in the electric field around AuNPs embedded in PEDOT:PSS and inbuilt electric field at the interfacial between CuPc and C60 is due to the surface plasmon resonance of AuNPs. The increase in these two factors increase the exciton generation in CuPc, dissociation at the interfacial layer, and charge carrier transfer which increases the collection of electrons and holes at cathode and anode.
关键词： Copper phthalocyanine,PEDOT:PSS,Solar cell,Gold nanoparticles,Materials chemistry,Fullerene,Materials science
更新于2025-09-11 14:15:04
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Plasmonic Nanobubbles in ‘Armored’ Surface Nanodroplets
摘要： Plasmonic nanobubbles are bubbles that are formed from local heat generated by noble metal nanoparticles under illumination of light at resonance. Understanding the formation and behavior of plasmonic nanobubbles is important for a broad suite of applications that rely on enhanced local heating of nanoparticles, such as in biomedical treatments and solar energy conversion. Here, we investigate formation, growth and dissolution of plasmonic bubbles in a model system of oil nanodroplets in water. Gold nanoparticles were located at the surface of nanodroplets immobilized on a substrate. We followed temporal evolution of plasmonic nanobubbles from ~ 200 nm in radius and above. Our experimental results show that there is an upper limit of the bubble size set by hosting droplet size, beyond which the nanobubbles burst. Nanobubbles grew, following the same growth exponent that was reported for a sub-millimeter bubble in contact with a bulk organic solvent. When the laser was switched off, the nanobubbles could remain for several minutes, much longer than the bubbles formed directly in water. The findings from this work may be valuable for light-driven chemical conversion in droplets or photothermal treatments involving immiscible phases.
关键词： bubble growth,Plasmonic nanobubbles,dissolution dynamics,nanodroplets,laser illumination,gold nanoparticles
更新于2025-09-11 14:15:04
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Synthesis of gold nanoparticles by pulsed laser-assisted reduction of aqueous gold precursor
摘要： In this paper, colloidal gold nanoparticles (GNPs) were synthesized by Nd:YAG (λ = 1064 nm) pulsed laser-assisted reduction (PLAR) of aqueous [AuCl4]?. In this process, during laser ablation of a Mo target in DI water, a [AuCl4]? precursor solution was being added dropwise in situ. UV–Vis absorption spectra showed distinct plasmonic absorption bands at 209 and 530 nm corresponding to Mo nanoparticles (NPs) and GNPs, respectively. Furthermore, no significant conversion for [AuCl4]? was found when it was added to aged Mo NPs or when it was irradiated in the lack of the Mo target. Using transmission electron microscope (TEM) images, it was found that precursor concentration and laser-ablation time can affect the population or size of GNPs. In PLAR with a small amount of KI solution in water, the GNPs size increases to ~ 50 nm via an iodine-induced particle fusion mechanism. The reduction mechanism was discussed based on metastable species intercation, producing the cavitation bubble during laser ablation.
关键词： Mo target,Nd:YAG laser,TEM,UV–Vis absorption,Pulsed laser-assisted reduction,Gold nanoparticles,KI solution
更新于2025-09-11 14:15:04