Nanoparticles: Optical Properties and Applications

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D:Materials and Processing".

Deadline for manuscript submissions: closed (20 June 2023) | Viewed by 9607

Special Issue Editors


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Guest Editor
Department of Physics and Astronomy, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA
Interests: nanoparticles; nanomaterials; optical properties; modeling and simulation; synthesis and characterization of nanoparticles
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA
Interests: AI in radiation detection and nuclear security; AI in radiation sensor networks
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Nanoparticles display a high surface-to-volume ratio and strong size-dependent optical and electronic properties, which make them ideal for developing highly sensitive devices or active agents.

The optical properties of nanoparticles spark the interests of researchers due to their strong extinction efficiency in the visible spectrum. These properties became one of the great triumphs of classical physics when Mie presented a solution to Maxwell's equations that describes the extinction spectra of spherical particles of arbitrary size.

Nanoparticles are currently of considerable interest due to their broad applications in catalysis, electrochemical sensors, gas sensors, optical biosensors, capacitors, read heads, nano-electronics, memories, transducers, integral chip inductors, surface-enhanced Raman scattering, gamma-ray detectors, optoelectronic devices, antibacterial activity, the degradation of environmental pollutants, biological labeling, cardiovascular implants, wound dressing, disease diagnosis and treatment, drug delivery, and cancer therapy.

Dr. Elham Gharibshahi
Dr. Miltiadis (Miltos) Alamaniotis
Guest Editors

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Keywords

  • metal nanoparticles
  • magnetic nanoparticles
  • composite nanoparticles
  • semiconductor nanoparticles
  • optical properties
  • modeling and simulation
  • synthesis and characterization of nanoparticles
  • applications of nanoparticles

Published Papers (4 papers)

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Research

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14 pages, 2703 KiB  
Article
Simulation and Synthesis of Cobalt (Co) Nanoparticles by Gamma Radiation Technique
by Elham Gharibshahi, Shahidan Radiman, Ahmadreza Ashraf, Elias Saion, Leila Gharibshahi and Sina Ashraf
Micromachines 2023, 14(7), 1383; https://doi.org/10.3390/mi14071383 - 6 Jul 2023
Cited by 1 | Viewed by 1338
Abstract
Cobalt nanoparticles were synthesized using the gamma radiolytic technique, and the particle size was found to be reduced from 12±1 to 7±1 nm by increasing the dose from 10 to 60 kGy. The UV-visible absorption spectra were measured and [...] Read more.
Cobalt nanoparticles were synthesized using the gamma radiolytic technique, and the particle size was found to be reduced from 12±1 to 7±1 nm by increasing the dose from 10 to 60 kGy. The UV-visible absorption spectra were measured and exhibited a steady absorption maxima at 517 nm in the UV region, which blue-shifted toward a lower wavelength with a decrease in particle size. By taking the conduction electrons of an isolated particle that are not entirely free but are instead bound to their respective quantum levels, the optical absorption of the cobalt nanoparticles can be calculated and simulated via intra-band quantum excitation for particle sizes comparable to the measured ones. We found that the simulated absorption maxima of electronic excitations corresponded to the measured absorption maxima. Moreover, the structural characterizations were performed utilizing dynamic light scattering (DLS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Full article
(This article belongs to the Special Issue Nanoparticles: Optical Properties and Applications)
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17 pages, 5704 KiB  
Article
Structure and Photoluminescence of WO3-x Aggregates Tuned by Surfactants
by Biben Wang, Xiaoxia Zhong, Haiyan Xu, Yongcai Zhang, Uros Cvelbar and Kostya (Ken) Ostrikov
Micromachines 2022, 13(12), 2075; https://doi.org/10.3390/mi13122075 - 25 Nov 2022
Cited by 3 | Viewed by 1599
Abstract
The optoelectronic properties of transition metal oxide semiconductors depend on their oxygen vacancies, nanostructures and aggregation states. Here, we report the synthesis and photoluminescence (PL) properties of substoichiometric tungsten oxide (WO3-x) aggregates with the nanorods, nanoflakes, submicro-spherical-like, submicro-spherical and micro-spherical [...] Read more.
The optoelectronic properties of transition metal oxide semiconductors depend on their oxygen vacancies, nanostructures and aggregation states. Here, we report the synthesis and photoluminescence (PL) properties of substoichiometric tungsten oxide (WO3-x) aggregates with the nanorods, nanoflakes, submicro-spherical-like, submicro-spherical and micro-spherical structures in the acetic acid solution without and with the special surfactants (butyric or oleic acids). Based on theory on the osmotic potential of polymers, we demonstrate the structural change of the WO3-x aggregates, which is related to the change of steric repulsion caused by the surfactant layers, adsorption and deformation of the surfactant molecules on the WO3-x nanocrystals. The WO3-x aggregates generate multi-color light, including ultraviolet, blue, green, red and near-infrared light caused by the inter-band transition and defect level-specific transition as well as the relaxation of polarons. Compared to the nanorod and nanoflake WO3-x aggregates, the PL quenching of the submicro-spherical-like, submicro-spherical and micro-spherical WO3-x aggregates is associated with the coupling between the WO3-x nanoparticles and the trapping centers arising from the surfactant molecules adsorbed on the WO3-x nanoparticles. Full article
(This article belongs to the Special Issue Nanoparticles: Optical Properties and Applications)
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15 pages, 6503 KiB  
Article
A Study of Nano-Tungsten Colloid Preparing by the Electrical Spark Discharge Method
by Chaur-Yang Chang, Kuo-Hsiung Tseng, Jui-Tsun Chang, Meng-Yun Chung and Zih-Yuan Lin
Micromachines 2022, 13(11), 2009; https://doi.org/10.3390/mi13112009 - 18 Nov 2022
Cited by 2 | Viewed by 1390
Abstract
This study developed an energy-enhanced (ee)-micro-electric discharge machining (EDM) system for preparing nano-tungsten (nano-W) colloids. This system enables spark discharge using tungsten wires immersed in deionized water, to produce nano-W colloids. Compared with the chemical preparation method, the processing environment for preparing colloids [...] Read more.
This study developed an energy-enhanced (ee)-micro-electric discharge machining (EDM) system for preparing nano-tungsten (nano-W) colloids. This system enables spark discharge using tungsten wires immersed in deionized water, to produce nano-W colloids. Compared with the chemical preparation method, the processing environment for preparing colloids in this study prevented nanoparticle escape. Among the nano-W colloids prepared using the ee-micro-EDM system and an industrial EDM system, the colloid prepared by the ee-micro-EDM system exhibited a more favorable absorbance, suspensibility, and particle size. The colloid prepared by the ee-micro-EDM system with a pulse on time and off time of 10–10 μs had an absorbance of 0.277 at a wavelength of 315 nm, ζ potential of −64.9 mV, and an average particle size of 164.9 nm. Transmission electron microscope imaging revealed a minimum particle size of approximately 11 nm, and the X-ray diffractometer spectrum verified that the colloid contained only W2.00 and W nanoparticles. Relative to industrial EDM applications for nano-W colloid preparation, the ee-micro-EDM system boasts a lower cost and smaller size, and produces nano-W colloids with superior performance. These advantages contribute to the competitiveness of the electrical spark discharge method in the preparation of high-quality nano-W colloids. Full article
(This article belongs to the Special Issue Nanoparticles: Optical Properties and Applications)
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Review

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32 pages, 2617 KiB  
Review
Biosynthesis of Copper Nanoparticles with Medicinal Plants Extracts: From Extraction Methods to Applications
by Aurora Antonio-Pérez, Luis Fernando Durán-Armenta, María Guadalupe Pérez-Loredo and Ana Laura Torres-Huerta
Micromachines 2023, 14(10), 1882; https://doi.org/10.3390/mi14101882 - 30 Sep 2023
Cited by 9 | Viewed by 4491
Abstract
Copper nanoparticles (CuNPs) can be synthesized by green methods using plant extracts. These methods are more environmentally friendly and offer improved properties of the synthesized NPs in terms of biocompatibility and functional capabilities. Traditional medicine has a rich history of utilization of herbs [...] Read more.
Copper nanoparticles (CuNPs) can be synthesized by green methods using plant extracts. These methods are more environmentally friendly and offer improved properties of the synthesized NPs in terms of biocompatibility and functional capabilities. Traditional medicine has a rich history of utilization of herbs for millennia, offering a viable alternative or complementary option to conventional pharmacological medications. Plants of traditional herbal use or those with medicinal properties are candidates to be used to obtain NPs due to their high and complex content of biocompounds with different redox capacities that provide a dynamic reaction environment for NP synthesis. Other synthesis conditions, such as salt precursor concentration, temperature, time synthesis, and pH, have a significant effect on the characteristics of the NPs. This paper will review the properties of some compounds from medicinal plants, plant extract obtention methods alternatives, characteristics of plant extracts, and how they relate to the NP synthesis process. Additionally, the document includes diverse applications associated with CuNPs, starting from antibacterial properties to potential applications in metabolic disease treatment, vegetable tissue culture, therapy, and cardioprotective effect, among others. Full article
(This article belongs to the Special Issue Nanoparticles: Optical Properties and Applications)
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