Various Types Of Metal Nanoparticles Research Articles

Antifungal Effect of Nanoparticles against COVID-19 Linked Black Fungus: A Perspective on Biomedical Applications.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible and pathogenic coronavirus that has caused a ‘coronavirus disease 2019’ (COVID-19) pandemic in multiple waves, which threatens human health and public safety. During this pandemic, some patients with COVID-19 acquired secondary infections, such as mucormycosis, also known as black fungus disease. Mucormycosis is a serious, acute, and deadly fungal infection caused by Mucorales-related fungal species, and it spreads rapidly. Hence, prompt diagnosis and treatment are necessary to avoid high mortality and morbidity rates. Major risk factors for this disease include uncontrolled diabetes mellitus and immunosuppression that can also facilitate increases in mucormycosis infections. The extensive use of steroids to prevent the worsening of COVID-19 can lead to black fungus infection. Generally, antifungal agents dedicated to medical applications must be biocompatible, non-toxic, easily soluble, efficient, and hypoallergenic. They should also provide long-term protection against fungal growth. COVID-19-related black fungus infection causes a severe increase in fatalities. Therefore, there is a strong need for the development of novel and efficient antimicrobial agents. Recently, nanoparticle-containing products available in the market have been used as antimicrobial agents to prevent bacterial growth, but little is known about their efficacy with respect to preventing fungal growth, especially black fungus. The present review focuses on the effect of various types of metal nanoparticles, specifically those containing silver, zinc oxide, gold, copper, titanium, magnetic, iron, and carbon, on the growth of various types of fungi. We particularly focused on how these nanoparticles can impact the growth of black fungus. We also discussed black fungus co-infection in the context of the global COVID-19 outbreak, and management and guidelines to help control COVID-19-associated black fungus infection. Finally, this review aimed to elucidate the relationship between COVID-19 and mucormycosis.

Metal nanoparticles as a promising technology in targeted cancer treatment

Traditional anticancer treatments have several limitations, but cancer is still one of the deadliest diseases. As a result, new anticancer drugs are required for the treatment of cancer. The use of metal nanoparticles (NPs) as alternative chemotherapeutic drugs is on the rise in cancer research. Metal NPs have the potential for use in a wide range of applications. Natural or surface-induced anticancer effects can be found in metals. The focus of this review is on the therapeutic potential of metal-based NPs. The potential of various types of metal NPs for tumor targeting will be discussed for cancer treatment. The in vivo application of metal NPs for solid tumors will be reviewed. Risk factors involved in the clinical application of metal NPs will also be summarized.

Green synthesis and characterization of silver nanoparticles using Tualang honey and evaluation of their antioxidant activities

Natural products are widely used in the synthesis of various types of metallic nanoparticles including silver nanoparticles. Tualang honey is one of the potential natural products which is rich in polyphenols and antioxidant capacity. This study aims to synthesise and characterise the silver nanoparticles by using Tualang honey through green method and evaluate their antioxidant activities. The formation of silver nanoparticles was examined by visual observation and further confirmed by UV-Visible spectrophotometer. The characterisation of silver nanoparticles was determined by using x-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy analysis. The in vitro antioxidant activity of silver nanoparticles was evaluated by 1,1-diphenyl-2-picrul hydrazyl and ferric reducing antioxidant power assays. The synthesis was confirmed physically through the colour changes from light brown to dark brown which indicates the reduction of silver ion to silver nanoparticles. UV-Visible spectrum results showed the highest absorbance peak at 410 nm. X-ray diffraction results showed that the face-centred cubic crystalline shaped nanoparticles were formed. Fourier transform infrared spectroscopy results revealed the available functional groups that act as capping and stabilising agents for the silver nanoparticles. Field emission scanning electron microscopy analysis exhibited the spherical shape and transmission electron microscopy confirmed the size range of silver nanoparticles of 22 nm. The silver nanoparticles exhibited remarkable antioxidant activity with 1,1-diphenyl-2-picrul hydrazyl and reducing antioxidant power values of 95.54 ± 0.96 (%) and 1032.30 ± 102.76 μM Fe(II), respectively. In conclusion, the silver nanoparticles synthesised by green method can be a potential source for the biomedical applications based on the beneficial properties of the Tualang honey.

High time resolution and high signal-to-noise monitoring of the bacterial growth kinetics in the presence of plasmonic nanoparticles

BackgroundEmerging concepts for designing innovative drugs (i.e., novel generations of antimicrobials) frequently include nanostructures, new materials, and nanoparticles (NPs). Along with numerous advantages, NPs bring limitations, partly because they can limit the analytical techniques used for their biological and in vivo validation. From that standpoint, designing innovative drug delivery systems requires advancements in the methods used for their testing and investigations. Considering the well-known ability of resazurin-based methods for rapid detection of bacterial metabolisms with very high sensitivity, in this work we report a novel optimization for tracking bacterial growth kinetics in the presence of NPs with specific characteristics, such as specific optical properties.ResultsArginine-functionalized gold composite (HAp/Au/arginine) NPs, used as the NP model for validation of the method, possess plasmonic properties and are characterized by intensive absorption in the UV/vis region with a surface plasmon resonance maximum at 540 nm. Due to the specific optical properties, the NP absorption intensively interferes with the light absorption measured during the evaluation of bacterial growth (optical density; OD600). The results confirm substantial nonspecific interference by NPs in the signal detected during a regular turbidity study used for tracking bacterial growth. Instead, during application of a resazurin-based method (Presto Blue), when a combination of absorption and fluorescence detection is applied, a substantial increase in the signal-to-noise ratio is obtained that leads to the improvement of the accuracy of the measurements as verified in three bacterial strains tested with different growth rates (E. coli, P. aeruginosa, and S. aureus).ConclusionsHere, we described a novel procedure that enables the kinetics of bacterial growth in the presence of NPs to be followed with high time resolution, high sensitivity, and without sampling during the kinetic study. We showed the applicability of the Presto Blue method for the case of HAp/Au/arginine NPs, which can be extended to various types of metallic NPs with similar characteristics. The method is a very easy, economical, and reliable option for testing NPs designed as novel antimicrobials.

Biosynthesis of Silver Nanoparticles Using Carum carvi Extract and its Inhibitory Effect on Growth of Candida albicans

Background: Biological synthesis of nanoparticles has emerged as a promising field of biotechnology. Various biological systems including fungi, yeasts, bacteria, and plants have been used for biosynthesis of nanoparticles. Silver nanoparticles have unique properties that make them ideal for various medical and industrial applications. Owing to high levels of organic reducing agents and ease of manipulation, plant extracts are widely used for biological generation of various types of metal nanoparticles. Objectives: The objective of the present study was to evaluate efficacy of Carum carvi extract in biosynthesis of silver nanoparticles and to investigate antifungal effects of the biosynthesized nanoparticles. Methods: Silver nanoparticles were synthesized by addition of silver nitrate solution into fresh extract of C. carvi. Characterization of the synthesized silver nanoparticles was performed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction analysis (XRD). Inhibitory effect of silver nanoparticles on Candida albicans growth was evaluated by serial microdilution method. Results: The results revealed the formation of spherical silver nanoparticles with an average size of 10 nm. Moreover, concentration of SNPs in a 25 mL sample containing both SNPs and plant extract biomass was 2.934 mg/L on average. Serial microdilution test showed that SNPs at the concentration of 50 g/mL can inhibit growth of the pathogen. Conclusions: The present study extends the existing literature about green synthesis of nanoparticles using plant tissues and extracts.

Plasma-assisted synthesis of Ag nanoparticles immobilized in mesoporous cellular foams and their catalytic properties for 4-nitrophenol reduction

Silver nanoparticle is an important catalyst for many chemical reactions and usually demands complex synthesis technology. In this work, a convenient and efficient plasma-assisted synthesis method was proposed to synthesize a new type of composite catalyst with Ag nanoparticles immobilized in 3D mesoporous cellular foams (MCFs) of silica. The plasma treatment under O2 atmosphere provided more activated silanol groups on the surface of MCF for the immobilization of Ag nanoparticles. The properties of immobilized Ag nanoparticles, such as smaller average size, higher loading, and better dispersion state greatly improved the reaction rate of the catalytic reduction of 4-nitrophenol (4-NP). Among them, with an average size of 6.0 nm and 2.6 wt% immobilized Ag nanoparticles, the catalyst MCF-100-Ag-0.01 showed the best catalytic activity for the reduction of 4-NP, that the apparent reduction rate constant was as large as 2.66 × 10−2s−1, and the turnover frequency coefficient was as extremely high as 8.97 × 1018 molecules g−1 s−1. The MCF-n-Ag-m composites could be expected as attractive catalysts for many other catalytic reactions. More importantly, this plasma-assisted synthesis approach could be a convenient way for the synthesis of highly active catalysts by immobilizing various types of metal nanoparticles in porous materials.

Origin and Nature of Spontaneous Shape Fluctuations in “Small” Nanoparticles

Normally chemically inert materials such as Au have been found to be catalytically active in the form of particles whose size is about 1 nm. Direct and indirect observations of various types of metal nanoparticles (NPs) in this size range, under catalytically relevant conditions for fuel-cell operation and catalysis, have indicated that such “small” particles can exhibit large spontaneous shape fluctuations and significant changes in shape and chemical activity in response to alterations in environmental conditions. NPs also normally exhibit facile coalescence when in proximity, impacting their stability and reactivity in applications. We perform molecular dynamics simulations on Ni nanoparticles, a commonly used NP in catalytic applications and carbon nanotube growth, in the ≈1 nm size regime where large-scale shape fluctuations have been observed experimentally. An analysis of the large-scale shape fluctuations observed in our simulations of these “small” NPs indicates that they are accompanied by collective motion of Ni atoms through the NP center, and we quantify these dynamic structures and their impact on NP shape. In contrast, stringlike collective atomic motion is confined to the NP interfacial region of NPs having a diameter greater than a few nanometers, and correspondingly, the overall NP shape remains roughly spherical, a case studied in our prior Ni NP simulations. Evidently, the large spontaneous NP shape fluctuations reflect a change in character of the collective atomic dynamics when the NPs become critically small in size.

Enhancing the Thermoelectric Properties of p-Type Bulk Bi-Sb-Te Nanocomposites via Solution-Based Metal Nanoparticle Decoration

Embedding nanosized particles in bulk thermoelectric materials is expected to lower the lattice thermal conductivity by enhancing the degree of interface phonon scattering, thus improving their thermoelectric figure of merit ZT. We have developed a wet chemical process to fabricate Bi0.5Sb1.5Te3-based thermoelectric nanocomposites which include nanometer-sized metal particles. By simple solution mixing of metal acetate precursors and Bi0.5Sb1.5Te3 powders in ethyl acetate as a medium for homogeneous incorporation, it is possible to apply various types of metal nanoparticles onto the surfaces of the thermoelectric powders. Next, bulk Bi0.5Sb1.5Te3 nanocomposites with homogeneously dispersed metal nanoparticles were fabricated using a spark plasma sintering technique. The lattice thermal conductivities were reduced by increasing the long-wavelength phonon scattering in the presence of metal nanoparticles, while the Seebeck coefficients increased for a few selected metal-decorated nanocomposites, possibly due to the carrier-energy-filtering effect. Finally, the figure of merit ZT was enhanced to 1.4 near room temperature. This approach highlights the feasibility of incorporating various types of nanoparticles into an alloy matrix starting by wet chemical routes, which is an effective means of improving the thermoelectric performance of Bi-Te-based alloys.

Nanoparticle‐based biologic mimetics

Centered on solid chemistry foundations, biology and materials science have reached a crossroad where bottom-up designs of new biologically important nanomaterials are a reality. The topics discussed here present the interdisciplinary field of creating biological mimics. Specifically, this discussion focuses on mimics that are developed using various types of metal nanoparticles (particularly gold) through facile synthetic methods. These methods conjugate biologically relevant molecules, e.g., small molecules, peptides, proteins, and carbohydrates, in conformationally favorable orientations on the particle surface. These new products provide stable, safe, and effective substitutes for working with potentially hazardous biologicals for applications such as drug targeting, immunological studies, biosensor development, and biocatalysis. Many standard bioanalytical techniques can be used to characterize and validate the efficacy of these new materials, including quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and enzyme-linked immunosorbent assay (ELISA). Metal nanoparticle-based biomimetics continue to be developed as potential replacements for the native biomolecule in applications of immunoassays and catalysis.

Sonolytical preparation of various types of metal nanoparticles in aqueous solution

Composite nanoparticles of Au, Pd and Pt, and nanoparticles of transition metal oxides, MnO2, were prepared by the sonochemical reduction of corresponding ions (Au(III), Pd(II), Pt(II), Pt(IV) and Mn(VII)) in an aqueous system in the presence of surfactants. The prepared noble metal particles were stable and the sizes were of the order of nanometer with narrow distribution. Surfactants were found to be stabilizers for the noble metal nanoparticles as well as important sources of reducing species for the metal ions. In binary metallic particles, which were prepared from aqueous mixed solutions of noble metal ions, three possible constitutional forms were obtained. MnO2 particles were reduce to water soluble Mn(II) ions by further sonication.