Characteristics Of Metal Nanoparticles Research Articles

Characteristics of Metallic Nanoparticles (Especially Silver Nanoparticles) as Anti-Biofilm Agents.

Biofilm-associated infections account for a large proportion of chronic diseases and pose a major health challenge. Metal nanoparticles offer a new way to address this problem, by impairing microbial growth and biofilm formation and by causing degradation of existing biofilms. This review of metal nanoparticles with antimicrobial actions included an analysis of 20 years of journal papers and patent applications, highlighting the progress over that time. A network analysis of relevant publications showed a major focus on the eradication of single-species biofilms formed under laboratory conditions, while a bibliometric analysis showed growing interest in combining different types of metal nanoparticles with one another or with antibiotics. The analysis of patent applications showed considerable growth over time, but with relatively few patents progressing to be granted. Overall, this profile shows that intense interest in metal nanoparticles as anti-biofilm agents is progressing beyond the confines of simple laboratory biofilm models and coming closer to clinical application. Looking to the future, metal nanoparticles may provide a sustainable approach to combatting biofilms of drug-resistant bacteria.

The Use of Capping Agents in the Stabilization and Functionalization of Metallic Nanoparticles for Biomedical Applications

AbstractThe study of nanoparticles (NPs) and their application in different areas of research, including biomedicine, is attracting the attention of researchers worldwide. Numerous investigations published during the last 20 years cover the fabrication of new materials in the nanoscale, and several uses have been proposed. Metallic nanoparticles (MNPs) have generated a high level of interest, based on improved optical, electrical and magnetic properties, ease of manufacturing, small sizes, and easy functionalization. However, when it comes to Biomedicine, particle aggregation, possible toxicity, and the need for effective cell internalization, still demand active investigation. The main strategy to overcome these drawbacks is possibly the use of capping agents to increase the stability of the particles in dispersion, their biocompatibility and functionalization. In this review, important concepts and characteristics of MNPs, are collected and described. The importance of surface coating for biomedical applications of metallic nanoparticles as well as the most used capping agents and metallic nanomaterials, are also discussed. Finally, the text includes examples and essential characteristics for the biomedical use of MNPs, including the consideration of important challenges. Aspects such as relevant biological activity, increased biocompatibility and functionalization potential are among the most desirable attributes of a capping agent.

Insight into the Structures and Electrocatalytic Activities of PdAg Alloy on RGO in the Oxidation of Ethanol, Ethylene Glycol and Glycerol

The biorenewable alcohols are identified as the promising energy in fuel cells, but the lack of efficient catalysts limits the electricity output. Here, we chemically grew the PdAg alloy nanoparticles (NPs) on reduced graphene oxide (RGO) to obtain PdxAgy(m)/RGO, and investigated the dependences of peak current densities on the metal loadings (m), Pd mole fractions (x), and sizes. The maximal peak currents of 1.86, 4.88, 14.3 and 13.6 × 104 mA cm−2 mgPd−1 were respectively achieved in the electrooxidation reactions of methanol, ethanol, ethylene glycol and glycerol. It is shown that the interactions of PdAg NPs with RGO can control the catalytic efficiencies through mediating the electronic characteristics of metal NPs and the reactant absorptions. Except the catalysts for methanol oxidation reaction, the efficient catalysis possesses the same lattice structure in PdAg alloys with the optimized m, and gives a common descriptor to select the catalyst with high catalytic activity.

Comparison of the Wild-Type Obligate Methylotrophic Bacterium Methylophilus quaylei and its Isogenic Streptomycin-Resistant Mutant via Metal Nanoparticle Generation

Metal nanoparticles synthesized by green methods with the use of microorganisms are currently one of the most closely studied types of nanomaterials. It has accurately been shown that the characteristics of metal nanoparticles generated in the presence of different bacteria vary. For the two isogenic strains of obligate methylotrophic bacteria of the wild type (M. quaylei MTT) and its streptomycin-resistant mutant (M. quaylei SMR), the pleiotropic character of streptomycin resistance mutation in the SMR cells has been revealed. It has been shown that both cultures can generate silver nanoparticles. There is a dramatic difference in the formation of palladium nanoparticles, which are formed only in the presence of cells of the streptomycin-resistant mutant M. quaylei SMR. This study shows that closely related isogenic strains of obligate methylotrophic bacteria can be distinguished by the spectra of biogenic nanoparticles of two noble metals. While palladium nanoparticles are only generated by the cells of the streptomycin-resistant mutant M. quaylei SMR, biogenic silver nanoparticles can be generated from both cultures. Thus, the assessment of the ability of microorganisms to form biogenic nanoparticles of different metals allows the revelation of subtle metabolic differences of even close cultures.

Role of Metallic Nanoparticles in Vaccinology: Implications for Infectious Disease Vaccine Development.

Subunit vaccines are safer but less immunogenic than live-attenuated vaccines or whole cell inactivated vaccines. Adjuvants are used to enhance and modulate antigen (Ag) immunogenicity, aiming to induce a protective and long-lasting immune response. Several molecules and formulations have been studied for their adjuvanticity, but only seven have been approved to formulate human vaccines. Metallic nanoparticles (MeNPs), particularly those containing gold and iron oxides, are widely used in medicine for diagnosis and therapy and have been used as carriers for drugs and vaccines. However, little is known about the immune response elicited by MeNPs or about their importance in the development of new vaccines. There is evidence that these particles display adjuvant characteristics, promoting cell recruitment, antigen-presenting cell activation, cytokine production, and inducing a humoral immune response. This review focuses on the characteristics of MeNPs that could facilitate the induction of a cellular immune response, particularly T-helper 1 and T-helper 17, and their potential functions as adjuvants for subunit vaccines.

Optical Characteristics of Metallic Nanoparticles During Melting by Laser Radiation

The cross sections and efficiencies of absorption, scattering, and attenuation of laser light with λ = 532 nm and in the 475–625 nm range for two-layered spherical gold nanoparticles with radii r00 = 10, 25, 50, 75, and 100 nm and radii of the solid and liquid cores ranging from 0–r00 are calculated theoretically and studied. It is found that the variation in the optical parameters of a nanoparticle with changes in the aggregate state of the material (melting) has a decisive influence on the heating dynamics of the nanoparticle above the melting point and on the subsequent thermal processes.

Comparison of nanoparticle generation by two plasma techniques: Dielectric barrier discharge and spark discharge

ABSTRACTDielectric barrier discharge (DBD) and spark discharge, two versatile atmospheric pressure plasma-based techniques, have been employed to generate nanoparticles. This study compares the characteristics of metal nanoparticles generated by a DBD reactor and a spark discharge generator with argon as the working gas. The gas temperature in the discharge region of the DBD reactor remained near room temperature, while that of the spark reactor varied from 470 to 1120 K and generally increased with increasing applied voltage amplitude in the range of 2–10 kV and driving frequency in the range of 1–10 kHz. Comparing to spark-generated nanoparticles under the same voltage, frequency, and flow rate, DBD-generated nanoparticles have smaller sizes, better monodispersity, and lower number concentrations. The number concentration of DBD-generated particles decreases significantly under high working voltage and frequency, while the number concentration of spark-generated particles increases with increasing worki...

Oscillatory characteristics of metallic nanoparticles inside lipid nanotubes

This study is concerned with the oscillatory behavior of metallic nanoparticles, and in particular silver and gold nanoparticles, inside lipid nanotubes (LNTs) using the continuum approximation along with the 6-12 Lennard-Jones (LJ) potential function. The nanoparticle is modeled as a dense sphere and the LNT is assumed to be comprised of six layers including two head groups, two intermediate layers and two tail groups. To evaluate van der Waals (vdW) interactions, analytical expressions are first derived through undertaking surface and volume integrals which are then validated by a fully numerical scheme based on the differential quadrature (DQ) technique. Using the actual force distribution between the two interacting molecules, the equation of motion is directly solved utilizing the Runge-Kutta numerical integration scheme to arrive at the time history of displacement and velocity of the inner core. Also, a semi-analytical expression incorporating both geometrical parameters and initial conditions is introduced for the precise evaluation of oscillation frequency. A comprehensive study is conducted to gain an insight into the influences of nanoparticle radius, LNT length, head and tail group thicknesses and initial conditions on the oscillatory behavior of the metallic nanoparticles inside LNTs. It is found that the escape velocity and oscillation frequency of silver nanoparticles are higher than those of gold ones. It is further shown that the oscillation frequency is less affected by the tail group thickness when compared to the head group thickness.

Complete set of techniques for evaluation of the main attestation characteristics of metal nanoparticles

The creation of nanomaterials (including namoparticles (NPs)) and their further use forms a chain that includes nanopowder manufacturing, diagnostics, and application. Establishing the main NP attestation characteristics using the proposed complimentary techniques is one link in this chain.

Variation of the plasma oscillation eigenfrequencies in metal nanoparticles upon their attachment to dielectric micro-objects

The possibilities of studying the structure of micro-objects by measuring optical characteristics of metal nanoparticles attached to them are analyzed. Approximate expressions describing variation of the plasmon dipole oscillation frequencies of a spherical nanoparticle depending on its position with respect to different objects are derived in the framework of a perturbative approach. Special attention is paid to the case of intrusion of a nanoparticle into a spherical object. Possible application of intrusion of nanoparticles into an object is discussed.