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[IEEE 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - Zatoka, Ukraine (2018.9.9-2018.9.14)] 2018 IEEE 8th International Conference Nanomaterials: Application & Properties (NAP) - The Study of the Activation of Antibacterial Activity of Silver Nanoparticles by Laser Radiation
摘要： Silver nanoparticles are known to have inhibitory and bactericidal effects and they play a significant role in the development of new antimicrobial substances against pathogenic microorganisms. In this article the minimum bactericidal concentration of the silver nanoparticles on two different bacteria cultures (Escherichia coli and Staphylococcus aureus) as well as the possibility to enhance their antimicrobial activity using laser irradiation was investigated. It was found, that solutions of silver nanoparticles at concentrations ≥ 3120 μg/ml cause death of both types of studied microorganisms. Dispersion of nanoparticles after laser irradiation caused the inhibition of Staphylococcus aureus at lower concentrations.
关键词： surface plasmon resonance,Escherichia coli,Staphylococcus aureus,bactericidal properties,silver nanoparticles
更新于2025-09-23 15:21:01
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Novel strategy for fabrication of sensing layer on thiol-functionalized fiber-optic tapers and their application as SERS probes
摘要： This work presents a new strategy to fabricate optical fiber surface-enhanced Raman scattering (SERS) probes with high-performance remote sensing prepared by thiol functionalization of silica fiber taper, and further in situ nucleation and growth of silver nanoparticles (AgNPs). The prepared fiber probes can effectively identify the analyte 4-aminothiophenol (4-ATP) with a limit of detection (LOD) as low as 2.15×10-11 M using a portable commercial Raman spectrometer. Simultaneously, such fiber probes have shown a good reproducibility with the relative standard deviation (RSD) value of 7.6%, and possessed high signal stability at room temperature over one month. Furthermore, this approach provides new insight into the fabrication of fiber SERS probe integrated the advantages in terms of sensitivity, reproducibility and stability, which shows great potential for practical SERS applications.
关键词： Thiol functionalization,SERS performance,Probe,Silver nanoparticles,Optical fiber
更新于2025-09-23 15:21:01
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Sensitive and selective detection of Cu2+ ions based on fluorescent Ag nanoparticles synthesized by R-phycoerythrin from marine algae Porphyra yezoensis
摘要： In this study, using a natural and green protein R-phycoerythrin (R-PE) extracted from marine Porphyra yezoensis as the stabilizer and reducer, silver nanoparticles (AgNPs) were synthesized. Based on this, a highly sensitive and selective method for the detection of Cu2+ ions was developed using R-PE-AgNPs as fluorescent probe. The interactions between R-PE-AgNPs and Cu2+ ions were systematically characterized by fluorescence spectroscopy, transmission electron microscopy (TEM), elemental mapping and Fourier transform infrared (FTIR). It was found that Cu2+ ions could cause aggregation of the R-PE-AgNPs, accompanied by the greatly increased particle size. Importantly, the method offered a wide linear detection range from 0 μM to 100.0 μM with a detection limit of 0.0190 μM. Moreover, the proposed method was successfully applied to analyze Cu2+ ions in tap water and lake water samples, acquiring satisfactory recovery between 91.6% and 102.2%. Such a green, fast and cost-effective fluorimetric method of the R-PE-AgNPs probe has great potential for tracing Cu2+ ions in diverse aqueous media.
关键词： Cu2+ detection,Silver nanoparticles,R-phycoerythrin,Water
更新于2025-09-23 15:21:01
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A novel fluorescent probe for ascorbic acid based on seed-mediated growth of silver nanoparticles quenching of carbon dots fluorescence
摘要： A novel, economic, and eco-friendly method of detecting ascorbic acid (AA) with excellent sensitivity was developed. The method took advantage of the fluorescence of carbon quantum dots (CDs) decreasing as the AA concentration increased through interactions between AA and Ag(I) in the presence of silver nanoparticle (AgNP) seeds, producing more AgNPs and allowing fluorescence resonance energy transfer between the AgNPs and the CDs. The change in the fluorescence intensity when AA was added was proportional to the AA concentration over the range 0–9.0 μM. The AA detection limit was 0.2 μM. This approach is a new method for determining the concentration of AA.
关键词： Fluorescence,Carbon dots,Ascorbic acid,Silver nanoparticles
更新于2025-09-23 15:21:01
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Peripherally functionalized based dendrimers as the template for synthesis of silver nanoparticles and investigation the affecting factors on their properties
摘要： Today, dendrimers (D) were introduced as a versatile template for the synthesis of nanoparticles (NPs). In this work, the stable silver nanoparticles (AgNPs) is successfully synthesized through the chemical reduction of AgNO3 using NaBH4 as a reducing agent. Synthesis of AgNPs was performed in the presence of different generations of citric acid-based dendrimers (G1, G2 and G3) and hydroxyl-terminated citric acid-based dendrimers (G1-OH, G2-OH and G3-OH). High-resolution transmission electron microscopy, electron diffraction and energy-dispersive X-ray analysis were used to characterize the synthesized AgNPs. UV–Vis results were used for the qualitative study of the synthesized AgNPs properties. With varying the molar ratio of dendrimer/Ag+, generations of dendrimers and the pH of the solution, the size and size distribution of AgNPs could be easily controlled at room temperature. The average diameter of the synthesized AgNPs in the presence of Gn-OH was in the range of 8–20 nm. Results show that G1-OH alkaline medium with 1:1 molar ratio of D/Ag is the optimum condition for the synthesis of AgNPs. All the obtained results from this study showed that controlling the medium conditions allows AgNPs with the desired size to be obtained.
关键词： Chemical reduction,Silver nanoparticles,Citric acid,Hydroxyl-terminated dendrimer,Dendrimer
更新于2025-09-23 15:21:01
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Different Silver Nanoparticles in One Crystal: Ag210(iPrPhS)71(Ph3P)5Cl and Ag211(iPrPhS)71(Ph3P)6Cl
摘要： Two pure silver nanoparticles (Ag210(iPrPhS)71(Ph3P)5Cl and Ag211(iPrPhS)71(Ph3P)6Cl labeled as SD/Ag210 and SD/Ag211 (SD = SunDi), were found to co-crystallize in forming compound 1. Single-crystal X-ray diffraction (SCXRD) revealed that they differ by only one Ag(PPh3). Their four-shell nanoparticles consist of three pure Ag metal shells (Ag19@Ag52@Ag45) shielded by a silver-organic Ag89(iPrPhS)71Cl[Ag(Ph3P)]n. outermost shell. The number (n) of Ag(Ph3P) is five for SD/Ag210 and six for SD/Ag211. The pseudo-fivefold symmetric Ag nanoparticles exhibit surface plasmon absorption similar to a true metallic state but at the nanoscale. The attributes of this work are i) it exemplifies the important effects of phosphine in stabilizing large silver nanoparticles; ii) it offers a platform to investigate the origin of differences in nanoscale metal materials, even differing by only one metal atom; and iii) it sheds light on the regioselective binding of auxiliary Ph3P on the surface of silver nanoparticles.
关键词： co-crystallization,core-shell,silver nanoparticles,alkyne,surface plasmon
更新于2025-09-23 15:21:01
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Generation of plasmonic hot carriers from d-bands in metallic nanoparticles
摘要： We present an approach to master the well-known challenge of calculating the contribution of d-bands to plasmon-induced hot carrier rates in metallic nanoparticles. We generalize the widely used spherical well model for the nanoparticle wavefunctions to flat d-bands using the envelope function technique. Using Fermi’s golden rule, we calculate the generation rates of hot carriers after the decay of the plasmon due to transitions either from a d-band state to an sp-band state or from an sp-band state to another sp-band state. We apply this formalism to spherical silver nanoparticles with radii up to 20 nm and also study the dependence of hot carrier rates on the energy of the d-bands. We find that for nanoparticles with a radius less than 2.5 nm, sp-band state to sp-band state transitions dominate hot carrier production, while d-band state to sp-band state transitions give the largest contribution for larger nanoparticles.
关键词： Fermi’s golden rule,plasmonic hot carriers,spherical well model,silver nanoparticles,d-bands,metallic nanoparticles,envelope function technique
更新于2025-09-23 15:19:57
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Metallic Core-Shell Photonic Crystals for Surface-Enhanced Raman Scattering (SERS)
摘要： Metallic core-shell substrate is specially used to serve ultrasensitive molecular detection down to concentration of micromolar level based on surface-enhanced Raman spectroscopy (SERS). Calculations show that the amorphous poly(methyl methacrylate) (PMMA) photonic crystals incorporated with metal nanoparticles which is either gold or silver nanoparticles can significantly increase the electromagnetic fields at the air dielectric interface, leading to remarkable Raman enhancement. Corresponding experiments and characterizations show the characteristic and performance of core-shell structures which present an excellent sensitivity, reproducibility and stability to act as SERS substrate.
关键词： Silver nanoparticles,Electromagnetic field,Poly(methyl methacrylate),SERS,Gold nanoparticles,Core-shell
更新于2025-09-23 15:19:57
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TD-DFT+TB: An Efficient and Fast Approach for Quantum Plasmonic Excitations
摘要： We study the quantum plasmonic features of gold and silver nanoparticles using TD-DFT+TB, a new density functional theory approach to the calculation of excited states, which combines a full DFT ground state with tight-binding approximations in the linear response calculation. In this framework, the optical properties of closed-shell Ag, Au and bimetallic Ag-Au nanoparticles with tetrahedral symmetry (with 20, 56, 120 and 165 atoms) and icosahedral structure (with 13, 55 and 147 atoms) were obtained and compared to full linear response time-dependent density functional theory (TD-DFT) as a reference and also time-dependent density functional based tight binding (TD-DFTB) as a low-cost alternative approach. We find an excellent agreement of TD-DFT+TB calculated absorption spectra with the TD-DFT reference with errors less than 0.15 eV in peak positions, while TD-DFTB shows larger errors of about 1 eV. The computational cost for the ground state calculation is identical for TD-DFT and TD-DFT+TB, but the excited state calculation becomes about a hundred times faster when applying the TB approximation and is then almost negligible for the overall timing of the calculation. In contrast to TD-DFTB, which can only be applied to element combinations for which a suitable DFTB parametrization is available, TD-DFT+TB can be applied to any combination of elements. To assess the accuracy of TD-DFT+TB for different combinations of atoms, the plasmonic properties of bimetallic clusters with different ratios of Ag and Au atoms were obtained and the trend of energy and intensity reproduced in good agreement with TD-DFT, which is not possible using TD-DFTB with standard parameter sets.
关键词： quantum plasmonic,bimetallic Ag-Au nanoparticles,gold and silver nanoparticles,optical properties,TD-DFT+TB
更新于2025-09-23 15:19:57
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Silvera??chitosan nanocomposite as a plasmonic platform for SERS sensing of polyaromatic sulfur heterocycles in oil fuel
摘要： Herein, a silver-chitosan nanocomposite for applications in surface enhanced Raman spectroscopy (SERS) sensing was proposed. It was shown that optically transparent chitosan coatings with 0.8 μm thickness allow penetration of target analytes to silver nanoparticles and the analysis in both polar and nonpolar solvents. Under the chosen conditions, chitosan formed continuously smooth films and coatings stabilizing rough nanostructured metallic surfaces and served as a suitable matrix for immobilization, uniform spreading, and preconcentration of the analytes. Polycyclic aromatic sulfur heterocycles were chosen as target analytes being one of the most important fuel quality markers, hazardous components and the hardest-to-remove impurities. For the most effective immobilization and even distribution of the analytes onto a nanostructured metallic surface, an additional polymer layer of chitosan was found to be needful. The presence of thin films of chitosan resulted in higher reproducibility of SERS spectra as compared to bare nanostructured silver substrates. Additionally, the developed nanocomposite SERS sensors provided the rapid determination of dibenzothiophene and its derivatives in isooctane with the threshold of detection better than 0.1 μM. This approach was successfully applied in the analysis of real fuel samples and the results agreed well with independently measured FTIR and GC-MS data.
关键词： chitosan,nonpolar solvents,polycyclic aromatic sulfur heterocycles,silver nanoparticles,surface enhanced Raman spectroscopy
更新于2025-09-23 15:19:57