Dye-doped nanoparticles have been investigated as bright, fluorescent probes for localization-based super-resolution microscopy. Nanoparticle size is important in super-resolution microscopy to get an accurate size of the object of interest from image analysis. Due to their self-blinking behavior and metal-enhanced fluorescence (MEF), Ag@SiO2and Au@Ag@SiO2nanoparticles have shown promise as probes for localization-based super-resolution microscopy. Here, several noble metal-based dye-doped core-shell nanoparticles have been investigated as self-blinking nanomaterial probes. It was observed that both the gold- and silver-plated nanoparticle cores exhibit weak luminescence under certain conditions due to the surface plasmon resonance bands produced by each metal, and the gold cores exhibit blinking behavior which enhances the blinking and fluorescence of the dye-doped nanoparticle. However, the silver-plated nanoparticle cores, while weakly luminescent, did not exhibit any blinking; the dye-doped nanoparticle exhibited the same behavior as the core fluorescent, but did not blink. Because of the blinking behavior, stochastic optical reconstruction microscopy (STORM) super-resolution analysis was able to be performed with performed on the gold core nanoparticles. A preliminary study on the use of these nanoparticles for localization-based super-resolution showed that these nanoparticles are suitable for use in STORM super resolution. Resolution enhancement was two times better than the diffraction limited images, with core sizes reduced to 15 nm using the hybrid Au–Ag cores.
more »
« less
Electronic Properties of Gold and Silver Nanoparticles Reveal Potential Applications for Medical Treatment Arial
Protein-functionalized nanoparticles introduce a potentially novel drug delivery method for medical therapeutics, including involvement in cancer therapies and as contrast agents in imaging. Gold and silver nanoparticles are of particular interest due to their distinctive properties. Extensive research shows that gold nanoparticles demonstrate incredible photothermal properties and non-toxic behavior, while silver nanoparticles exhibit antibacterial properties but increase toxicity for human use. However, little is known regarding the properties or applications of hybrid silver-gold particles. This study measured the UV-Vis absorbance spectrum for 40 nm diameter Au, streptavidin-conjugated Au, Ag@Au hybrid, Ag nanoparticles, and Transient Absorbance Spectra of Au. Analysis indicates that the hybrid particles exhibit characteristics of both Ag and Au particles, implying potential applications similar to both Ag and Au nanoparticles.
more »
« less
- Award ID(s):
- 2000281
- PAR ID:
- 10497327
- Publisher / Repository:
- Zenodo
- Date Published:
- Journal Name:
- Journal of advanced technological education
- Volume:
- 2
- Issue:
- 2
- ISSN:
- 2832-9635
- Page Range / eLocation ID:
- 92-99
- Subject(s) / Keyword(s):
- nanoparticles nano-bioconjugates UV-Vis Spectroscopy hybrid nanoparticles
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Reliability, shelf time, and uniformity are major challenges for most metallic nanostructures for surface‐enhanced Raman spectroscopy (SERS). Due to the randomness of the localized field supported by silver and gold nanopatterns in conventional structures, the quantitative analysis of the target in the practical application of SERS sensing is a challenge. Here, a superabsorbing metasurface with hybrid Ag–Au nanostructures is proposed. A two‐step process of deposition plus subsequent thermal annealing is developed to shrink the gap among the metallic nanoparticles with no top‐down lithography technology involved. Because of the light trapping strategy enabled by the hybrid Ag–Au metasurface structure, the excitation laser energy can be localized at the edges of the nanoparticles more efficiently, resulting in enhanced sensing resolution. Intriguingly, because more hot spots are excited over a given area with higher density of small nanoparticles, the spatial distribution of the localized field is more uniform, resulting in superior performance for potential quantitative sensing of drugs (i.e., cocaine) and chemicals (i.e., molecules with thiol groups in this report). Furthermore, the final coating of the second Au nanoparticle layer improves the reliability of the chip, which is demonstrated effective after 12 month shelf time in an ambient storage environment.more » « less
-
This article belongs to the Special Issue Synthesis and Applications of Gold Nanoparticles) Rodolphe Antoine (Ed.)This research focuses on the plant-mediated green synthesis process to produce gold nanoparticles (Au NPs) using upland cress (Barbarea verna), as various biomolecules within the upland cress act as both reducing and capping agents. The synthesized gold nanoparticles were thoroughly characterized using UV-vis spectroscopy, surface charge (zeta potential) analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results indicated the synthesized Au NPs are spherical and well-dispersed with an average diameter ~11 nm and a characteristic absorbance peak at ~529 nm. EDX results showed an 11.13% gold content. Colloidal Au NP stability was confirmed with a zeta potential (ζ) value of −36.8 mV. X-ray diffraction analysis verified the production of crystalline face-centered cubic gold. Moreover, the antimicrobial activity of the Au NPs was evaluated using Gram-negative Escherichiacoli and Gram-positive Bacillus megaterium. Results demonstrated concentration-dependent antimicrobial properties. Lastly, applications of the Au NPs in catalysis and biomedicine were evaluated. The catalytic activity of Au NPs was demonstrated through the conversion of 4-nitrophenol to 4-aminophenol which followed first-order kinetics. Cellular uptake and cytotoxicity were evaluated using both BMSCs (stem) and HeLa (cancer) cells and the results were cell type dependent. The synthesized Au NPs show great potential for various applications such as catalysis, pharmaceutics, and biomedicine.more » « less
-
Abstract Transparent microelectrodes have received much attention from the biomedical community due to their unique advantages in concurrent crosstalk‐free electrical and optical interrogation of cell/tissue activity. Despite recent progress in constructing transparent microelectrodes, a major challenge is to simultaneously achieve desirable mechanical stretchability, optical transparency, electrochemical performance, and chemical stability for high‐fidelity, conformal, and stable interfacing with soft tissue/organ systems. To address this challenge, we have designed microelectrode arrays (MEAs) with gold‐coated silver nanowires (Au–Ag NWs) by combining technical advances in materials, fabrication, and mechanics. The Au coating improves both the chemical stability and electrochemical impedance of the Au–Ag NW microelectrodes with only slight changes in optical properties. The MEAs exhibit a high optical transparency >80% at 550 nm, a low normalized 1 kHz electrochemical impedance of 1.2–7.5 Ω cm2, stable chemical and electromechanical performance after exposure to oxygen plasma for 5 min, and cyclic stretching for 600 cycles at 20% strain, superior to other transparent microelectrode alternatives. The MEAs easily conform to curvilinear heart surfaces for colocalized electrophysiological and optical mapping of cardiac function. This work demonstrates that stretchable transparent metal nanowire MEAs are promising candidates for diverse biomedical science and engineering applications, particularly under mechanically dynamic conditions.more » « less
-
ABSTRACT Graphene oxide serves as a precursor to various technologies, which include batteries, biosensors, solar cells, and supercapacitors. Gold nanoparticles exhibit excellent electrochemical and photophysical properties, allowing for electronic absorption and the ability to absorb light energy at the plasmonic wavelength. Palladium nanoparticles are highly sensitive and functional in room temperature, making it an ideal metal for catalytic applications. We report the synthesis of functional graphene oxide from graphite flakes followed by the insertion of gold and palladium nanoparticles through an oleylamine ligand. In this report, the fermi level of graphene oxide (GOx), gold-graphene oxide (Au-GOx), and palladium-graphene oxide (Pd-GOx) was shown to be effectively controlled. Additionally, each system showed complete solubility in ethanol and in the case of Au-GOx, enhanced solubility was seen in tetrahydrofuran as well.more » « less
An official website of the United States government

