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Nanoparticles Based on Noble Metals: From Synthesis to Application

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A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanocomposite Materials".

Deadline for manuscript submissions: closed (30 July 2022) | Viewed by 23865

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Special Issue Editor

Prof. Dr. Emilia Iglesias Martínez

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Guest Editor

Chemistry Department & CICA, Universidad de La Coruña (UDC), La Coruña, Spain
Interests: supramolecular chemistry; self-assembly; molecular recognition; nanomaterials; nanosensors; nitrosation reaction; keto-enol tautomerism

Special Issue Information

Dear Colleagues,

Noble metal nanoparticles (AuNPs, AgNPs, PtNPs, etc.) have attracted significant attention for advanced applications in different fields such as nano-drug delivery systems, cancer therapy, biosensors, catalysis, or energy devices. Noble bimetallic and trimetallic nanoparticles have superior performance as compared to their monometallic counterparts, which depends on their composition, size and shape. Metallic nanoparticles combined/coated with functionalized organic or biomolecules, including drugs, polymers, enzymes, etc., give rise to advanced core shell with interesting physical characteristics and potential applications. The controlled synthesis, characterization, and applications of these nanomaterials are a hot area for research.

This Special Issue of Nanomaterials focuses on the synthesis, properties and applications of noble metal nanoparticles and aims to collect communications, full papers, or reviews covering a broad range of subjects from nanomaterial synthesis to characterization techniques and their applications.

We are grateful to the authors who will participate in this issue of Nanomaterials, and we hope that all articles herein will contribute to the development of this fascinating area of research, as well as innovation in the field.

Prof. Dr. Emilia Iglesias Martínez
Guest Editor

Manuscript Submission Information

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Keywords

Noble metal nanoparticles synthesis methods
Noble bimetallic and trimetallic nanoparticles
Functionalized noble metallic nanomaterials
Characterization techniques (e.g., TEM, SERS, DLS, absorption, emission and excitation spectroscopy, etc.)
Noble metallic nanoparticles with enhanced optical properties
Biomedical applications and biocompatibility

Published Papers (6 papers)

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Research

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22 pages, 5239 KiB

Open AccessArticle

Size and Zeta Potential Clicked Germination Attenuation and Anti-Sporangiospores Activity of PEI-Functionalized Silver Nanoparticles against COVID-19 Associated Mucorales (Rhizopus arrhizus)

by Atul Kumar Tiwari, Munesh Kumar Gupta, Govind Pandey, Ragini Tilak, Roger J. Narayan and Prem C. Pandey

Nanomaterials 2022, 12(13), 2235; https://doi.org/10.3390/nano12132235 - 29 Jun 2022

Cited by 9 | Viewed by 2057

Abstract

The SARS-CoV-2 infections in Indian people have been associated with a mucormycotic fungal infection caused by the filamentous fungi Rhizopus arrhizus. The sporangiospores of R. arrhizus are omnipresent in the environment and cause infection through inhalation or ingestion of contaminated air and foods. Therefore, the anti-sporangiospore activity of polyethyleneimine functionalized silver nanoparticles (PEI-f-Ag-NPs) with variable size and surface charge as a function of the molecular weight of PEI was explored. The results showed that both PEI-f-AgNP-1 and PEI-f-AgNP-2, potentially, attenuated the germination and reduced the viability of sporangiospores. Furthermore, the results showed that the minimum inhibitory concentration (MIC) values of both PEI-f-AgNP-1 and PEI-f-AgNP-2 (1.65 and 6.50 μg/mL, respectively) were dependent on the nanoparticle size and surface ζ potentials. Similarly, the sporangiospore germination inhibition at MIC values was recorded, showing 97.33% and 94% germination inhibition, respectively, by PEI-f-AgNP-1 and 2 within 24 h, respectively. The confocal laser scanning microscopy, SEM-EDS, and confocal Raman spectroscopy investigation of PEI-f-Ag-NPs treated sporangiospores confirmed size and surface charge-dependent killing dynamics in sporangiospores. To the best of our knowledge, this is the first investigation of the polyethyleneimine functionalized silver nanoparticle-mediated size and surface charge-dependent anti-sporangiospore activity against R. arrhizus, along with a possible antifungal mechanism. Full article

(This article belongs to the Special Issue Nanoparticles Based on Noble Metals: From Synthesis to Application)

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20 pages, 33785 KiB

Open AccessArticle

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO₃ Nanofillers

by Nadejda Horchidan, Cristina Elena Ciomaga, Lavinia Petronela Curecheriu, George Stoian, Mihaela Botea, Mihaela Florea, Valentin Adrian Maraloiu, Lucian Pintilie, Florin Mihai Tufescu, Vasile Tiron, Aurelian Rotaru and Liliana Mitoseriu

Nanomaterials 2022, 12(6), 934; https://doi.org/10.3390/nano12060934 - 12 Mar 2022

Cited by 9 | Viewed by 3175

Abstract

The role of Ag addition on the structural, dielectric, and mechanical harvesting response of 20%(xAg − (1 − x)BaTiO₃) − 80%PVDF (x = 0, 2, 5, 7 and 27 vol.%) flexible composites is investigated. The inorganic fillers were realized by precipitating fine (~3 nm) silver nanoparticles onto BaTiO₃ nanoparticles (~60 nm average size). The hybrid admixtures with a total filling factor of 20 vol.% were embedded into the PVDF matrix. The presence of filler enhances the amount of β-PVDF polar phase and the BaTiO₃ filler induces an increase of the permittivity from 11 to 18 (1 kHz) in the flexible composites. The addition of increasing amounts of Ag is further beneficial for permittivity increase; with the maximum amount (x = 27 vol.%), permittivity is three times larger than in pure PVDF (

ε_{r}

~ 33 at 1 kHz) with a similar level of tangent losses. This result is due to the local field enhancement in the regions close to the filler-PVDF interfaces which are additionally intensified by the presence of silver nanoparticles. The metallic addition is also beneficial for the mechanical harvesting ability of such composites: the amplitude of the maximum piezoelectric-triboelectric combined output collected in open circuit conditions increases from 0.2 V/cm² (PVDF) to 30 V/cm² for x = 27 vol.% Ag in a capacitive configuration. The role of ferroelectric and metallic nanoparticles on the increasing mechanical-electric conversion response is also been explained. Full article

(This article belongs to the Special Issue Nanoparticles Based on Noble Metals: From Synthesis to Application)

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22 pages, 6478 KiB

Open AccessArticle

Composition-Dependent Cytotoxic and Antibacterial Activity of Biopolymer-Capped Ag/Au Bimetallic Nanoparticles against Melanoma and Multidrug-Resistant Pathogens

by Alfonso Nieto-Argüello, David Medina-Cruz, Yeremi S. Pérez-Ramírez, Sergio A. Pérez-García, Miguel A. Velasco-Soto, Zeinab Jafari, Israel De Leon, María Ujué González, Yves Huttel, Lidia Martínez, Álvaro Mayoral, Thomas J. Webster, José M. García-Martín and Jorge L. Cholula-Díaz

Nanomaterials 2022, 12(5), 779; https://doi.org/10.3390/nano12050779 - 25 Feb 2022

Cited by 12 | Viewed by 2706

Abstract

Nanostructured silver (Ag) and gold (Au) are widely known to be potent biocidal and cytotoxic agents as well as biocompatible nanomaterials. It has been recently reported that combining both metals in a specific chemical composition causes a significant enhancement in their antibacterial activity against antibiotic-resistant bacterial strains, as well as in their anticancer effects, while preserving cytocompatibility properties. In this work, Ag/Au bimetallic nanoparticles over a complete atomic chemical composition range were prepared at 10 at% through a green, highly reproducible, and simple approach using starch as a unique reducing and capping agent. The noble metal nanosystems were thoroughly characterized by different analytical techniques, including UV-visible and FT-IR spectroscopies, XRD, TEM/EDS, XPS and ICP-MS. Moreover, absorption spectra simulations for representative colloidal Ag/Au-NP samples were conducted using FDTD modelling. The antibacterial properties of the bimetallic nanoparticles were determined against multidrug-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus, showing a clear dose-dependent inhibition even at the lowest concentration tested (5 µg/mL). Cytocompatibility assays showed a medium range of toxicity at low and intermediate concentrations (5 and 10 µg/mL), while triggering an anticancer behavior, even at the lowest concentration tested, in a process involving reactive oxygen species production per the nanoparticle Au:Ag ratio. In this manner, this study provides promising evidence that the presently fabricated Ag/Au-NPs should be further studied for a wide range of antibacterial and anticancer applications. Full article

(This article belongs to the Special Issue Nanoparticles Based on Noble Metals: From Synthesis to Application)

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Graphical abstract

14 pages, 4210 KiB

Open AccessFeature PaperArticle

Antibacterial Effect of Colloidal Suspensions Varying in Silver Nanoparticles and Ions Concentrations

by Varvara Platania, Alexandra Kaldeli-Kerou, Theodora Karamanidou, Maria Kouki, Alexander Tsouknidas and Maria Chatzinikolaidou

Nanomaterials 2022, 12(1), 31; https://doi.org/10.3390/nano12010031 - 23 Dec 2021

Cited by 14 | Viewed by 3024

Abstract

A lot of effort has been dedicated recently to provide a better insight into the mechanism of the antibacterial activity of silver nanoparticles (AgNPs) colloidal suspensions and their released silver ionic counterparts. However, there is no consistency regarding whether the antibacterial effect displayed at cellular level originates from the AgNPs or their ionic constitutes. To address this issue, three colloidal suspensions exhibiting different ratios of AgNPs/silver ions were synthesized by a wet chemistry method in conjunction with tangential flow filtration, and were characterized and evaluated for their antimicrobial properties against two gram-negative, Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), and two gram-positive, Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis), bacterial strains. The produced samples contained 25% AgNPs and 75% Ag ions (AgNP_25), 50% AgNPs and 50% Ag ions (AgNP_50), and 100% AgNPs (AgNP_100). The sample AgNP_100 demonstrated the lowest minimum inhibitory concentration values ranging from 4.6 to 15.6 ppm for all four bacterial strains, while all three samples indicated minimum bactericidal concentration (MBC) values ranging from 16.6 ppm to 62.5 ppm against all strains. An increase in silver ions content results in higher bactericidal activity. All three samples were found to lead to a significant morphological damage by disruption of the bacterial cell membranes as analyzed by means of scanning electron microscopy (SEM). The growth kinetics demonstrated that all three samples were able to reduce the bacterial population at a concentration of 3.1 ppm. SEM and growth kinetic data underline that S. epidermidis is the most sensitive among all strains against the investigated samples. Our results showed that all three AgNPs colloidal suspensions exhibited strong antibacterial properties and, thus, they can be applied in medical devices and antimicrobial control systems. Full article

(This article belongs to the Special Issue Nanoparticles Based on Noble Metals: From Synthesis to Application)

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8 pages, 1194 KiB

Open AccessArticle

Transformation from Self-Focusing to Self-Defocusing of Silver Nanoparticles

by Jijuan Jiang, Yang Jia, Tong Wu and Yachen Gao

Nanomaterials 2021, 11(10), 2485; https://doi.org/10.3390/nano11102485 - 24 Sep 2021

Cited by 2 | Viewed by 1455

Abstract

The nonlinear refraction of silver nanoparticles (AgNPs) in n-hexane was studied by using the closed-aperture Z-scan technique with a 532 nm nanosecond laser. It was found that, the nonlinear refraction of AgNPs shows the coexistence and transformation from self-focusing to self-defocusing. Specifically, self-focusing occurs at low excitation intensity, self-defocusing occurs at high excitation intensity, and coexistence of self-focusing and self-defocusing occurs at relatively moderate excitation intensity. The experimental results were analysed and discussed in terms of third-order and fifth-order nonlinear refractive effect. Specifically, the self-focusing is caused by the positive third-order nonlinear refraction, the self-defocusing is induced by the negative fifth-order nonlinear refraction, and the transformation from the self-focusing to self-defocusing at medium excitation intensity is caused by the competition of third-order and fifth-order nonlinear refraction. Finally, the third-order refractive index and fifth-order refractive index were obtained. Full article

(This article belongs to the Special Issue Nanoparticles Based on Noble Metals: From Synthesis to Application)

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Review

Jump to: Research

22 pages, 3984 KiB

Open AccessReview

Green Nanotechnology: Plant-Mediated Nanoparticle Synthesis and Application

by Faryad Khan, Mohammad Shariq, Mohd Asif, Mansoor Ahmad Siddiqui, Pieter Malan and Faheem Ahmad

Nanomaterials 2022, 12(4), 673; https://doi.org/10.3390/nano12040673 - 17 Feb 2022

Cited by 71 | Viewed by 10274

Abstract

The key pathways for synthesizing nanoparticles are physical and chemical, usually expensive and possibly hazardous to the environment. In the recent past, the evaluation of green chemistry or biological techniques for synthesizing metal nanoparticles from plant extracts has drawn the attention of many researchers. The literature on the green production of nanoparticles using various metals (i.e., gold, silver, zinc, titanium and palladium) and plant extracts is discussed in this study. The generalized mechanism of nanoparticle synthesis involves reduction, stabilization, nucleation, aggregation and capping, followed by characterization. During biosynthesis, major difficulties often faced in maintaining the structure, size and yield of particles can be solved by monitoring the development parameters such as temperature, pH and reaction period. To establish a widely accepted approach, researchers must first explore the actual process underlying the plant-assisted synthesis of a metal nanoparticle and its action on others. The green synthesis of NPs is gaining attention owing to its facilitation of the development of alternative, sustainable, safer, less toxic and environment-friendly approaches. Thus, green nanotechnology using plant extract opens up new possibilities for the synthesis of novel nanoparticles with the desirable characteristics required for developing biosensors, biomedicine, cosmetics and nano-biotechnology, and in electrochemical, catalytic, antibacterial, electronics, sensing and other applications. Full article

(This article belongs to the Special Issue Nanoparticles Based on Noble Metals: From Synthesis to Application)

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