A review on plants extract mediated synthesis of silver nanoparticles for antimicrobial applications: A green expertise.

Zinc oxide nanoparticles (ZnO NPs) are used in an increasing number of industrial products such as rubber, paint, coating, and cosmetics In the past two decades, ZnO NPs have become one of the most popular metal oxide nanoparticles in biological applications due to their excellent biocompatibility, economic, and low toxicity ZnO NPs have emerged a promising potential in biomedicine, especially in the fields of anticancer and antibacterial fields, which are involved with their potent ability to trigger excess reactive oxygen species (ROS) production, release zinc ions, and induce cell apoptosis In addition, zinc is well known to keep the structural integrity of insulin So, ZnO NPs also have been effectively developed for antidiabetic treatment Moreover, ZnO NPs show excellent luminescent properties and have turned them into one of the main candidates for bioimaging Here, we summarize the synthesis and recent advances of ZnO NPs in the biomedical fields, which will be helpful for facilitating their future research progress and focusing on biomedical fields

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The Advancing of Zinc Oxide Nanoparticles for Biomedical Applications

We studied melting and freezing of Ni nanoclusters with up to 8007 atoms ~5.7 nm! using molecular dynamics with the quantum-Sutten‐Chen many-body force field. We find a transition from cluster or molecular behavior below ;500 atoms to a mesoscale nanocrystal regime ~well-defined bulk and surface properties! above ;750 atoms ~2.7 nm!. We find that the mesoscale nanocrystals melt via surface processes, leading to Tm,N5Tm,bulk2aN 21/3 , dropping from Tm,bulk51760 K to Tm,336 5980 K. Cooling from the melt leads first to supercooled clusters with icosahedral local structure. For N.400 the supercooled clusters transform to FCC grains, but smaller values of N lead to a glassy structure with substantial icosahedral character. © 2001 American Institute of Physics. @DOI: 10.1063/1.1373664#

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Melting and crystallization in Ni nanoclusters: The mesoscale regime

In recent years, zinc oxide nanoparticles (ZnO NPs) have gained tremendous attention attributed to their unique properties. Notably, evidence has shown that zinc is an important nutrient in living organisms. As such, both prokaryotes and eukaryotes including bacteria, fungi and yeast are exploited for the synthesis of ZnO NPs by using microbial cells or enzyme, protein and other biomolecules compounds in either an intracellular or extracellular route. ZnO NPs exhibit antimicrobial properties, however, the properties of nanoparticles (NPs) are depended upon on their size and shape, which make them specific for various applications. Nevertheless, the desired size and shape of NPs can be obtained through the optimization process of microbes mediated synthesis by manipulating their reaction conditions. It should be noted that ZnO NPs are synthesized by various chemical and physical methods. Nonetheless, these methods are expensive and not environmentally friendly. On that account, the microbes mediated synthesis of ZnO NPs have rapidly evolved recently where the microbes are cleaner, eco-friendly, non-toxic and biocompatible as the alternatives to chemical and physical practices. Moreover, zinc in the form of NPs is more effective than their bulk counterparts and thus, they have been explored for many potential applications including in animals industry. Notably, with the advent of multi-drug resistant strains, ZnO NPs have emerged as the potential antimicrobial agents. This is mainly due to their superior properties in combating a broad spectrum of pathogens. Moreover, zinc is known as an essential trace element for most of the biological function in the animal’s body. As such, the applications of ZnO NPs have been reported to significantly enhance the health and production of the farm animals. Thus, this paper reviews the biological synthesis of ZnO NPs by the microbes, the mechanisms of the biological synthesis, parameters for the optimization process and their potential application as an antimicrobial agent and feed supplement in the animal industry as well as their toxicological hazards on animals.

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Microbial synthesis of zinc oxide nanoparticles and their potential application as an antimicrobial agent and a feed supplement in animal industry: a review

Abstract Functionalised hexagonal mesoporous SBA-15-type molecular sieves with pore sizes in the range 51–56 A have been prepared using non-ionic block copolymers and used for immobilisation of the enzyme trypsin. Thiol, chloride, amine, and carboxylic acid functional groups were attached by siloxypropane tethers to the siliceous surface of SBA-15 via two methods, post-synthesis grafting and in situ synthesis. Phenylsiloxane groups were also incorporated using these two methods. The resulting solids were rendered porous and used to immobilise trypsin, giving variable but in general higher retention of the enzyme molecules than was observed on unfunctionalised, purely siliceous SBA-15. The resulting supported enzyme catalysts were shown to be active and stable catalysts for the hydrolysis of N -α-benzoyl-DL-arginine-4-nitroanilide (BAPNA). The solids prepared by supporting the enzyme on thiol-functionalised SBA-15 prepared by in situ synthesis were found to be the most promising. Trypsin supported on thiol-functionalised SBA-15 was shown to be recyclable.

Enzyme Immobilization Using SBA15 Mesoporous Molecular Sieves with Functionalised Surfaces

Evaluation of antibacterial and antioxidant potential of the zinc oxide nanoparticles synthesized by aqueous and polyol method

An efficient large-scale clonal propagation protocol has been described for Withania somnifera (L.) Dunal, a valuable medicinal plant, using cotyledonary nodes derived from axenic seedlings. Murashige and Skoog’s (Physiol Plant 15:473–497, 1962) (MS) medium supplemented with 1.0 mg l−1N6-benzyladenine (BA) was found to be optimum for production of multiple shoots (100 % shoot proliferation frequency and 16.93 shoots per explant). Successive shoot cultures were established by repeatedly sub-culturing the original cotyledonary node on a fresh medium after each harvest of newly formed shoots. Multiple shoot proliferation was also achieved from nodal segments derived from in vitro raised shoots on MS medium augmented with 1.0 mg l−1 BA. Regenerated shoots were best rooted (95.2 %, 38.7 roots per shoot) in half-strength MS medium supplemented with 1.0 mg l−1 indole-3-butyric acid. The plantlets were successfully acclimated and established in soil. Random amplified polymorphic DNA and inter-simple sequence repeats analysis revealed a homogeneous amplification profile for all micropropagated plants analyzed validating the genetic fidelity of the in vitro regenerated plants.

In vitro plant regeneration from cotyledonary nodes of Withania somnifera (L.) Dunal and assessment of clonal fidelity using RAPD and ISSR markers

The thermal stabilities and dynamics of small nickel clusters consisting of 7 to 23 atoms have been studied extensively by a molecular dynamics method based on a tight-binding many-body potential. Physical properties such as the caloric curve, melting temperature, and bond-length fluctuations are computed. The simulation indicates that the clusters undergo solid-liquid phase change with the increase in internal energy. The melting temperature is found to be a non-monotonic function of cluster size with some clusters exhibiting pre-melting behaviour. Considerable depression in the melting point of small clusters has been observed - the highest melting temperature for small clusters is found to be almost half the value for the bulk nickel. The results are discussed in the light of recent nanocalorimetric experiments on small finite particles.

https://iopscience.iop.org/article/10.1088/0953-8984/10/48/008/pdf

Thermodynamics of small nickel clusters

Thermodynamics of Small Nickel Clusters

There is an ever-increasing commercial demand for nanoparticles due to their extensive applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and eco-friendly chemical reaction for the green synthesis of silver nanoparticles from Centella asiatica L. has been developed. Here we report for the first time, to the best of our knowledge, the synthesis of silver nanoparticles of varying sizes using aqueous extract of leaves of Centella asiatica L. at room temperature. The synthesized nanoparticles are evaluated for its antimicrobial activity against human pathogens, Staphylococcus aureus (MTCC 9542) which is a common agent for skin infections. Synthesized nanoparticles were characterized using UV-visible spectrophotometer, Fourier Transmission Infra Red Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and XRay Diffraction (XRD). Novelty of this present study is that the plant extract is very cost effective, eco-friendly; economic and effective alternative for the large scale synthesis of silver nanoparticles for antibacterial activity. The activity of the conjugates is still an open question and needs further study.

Padan Kumar Jena

Papers

Evaluation of antibacterial and antioxidant potential of the zinc oxide nanoparticles synthesized by aqueous and polyol method

In vitro plant regeneration from cotyledonary nodes of Withania somnifera (L.) Dunal and assessment of clonal fidelity using RAPD and ISSR markers

Thermodynamics of small nickel clusters

Thermodynamics of Small Nickel Clusters

Green synthesis of silver nanoparticles using leaves extract of centella asiatica l. for studies against human pathogens