While metal nanoparticles are being increasingly used in many sectors of the economy, there is growing interest in the biological and environmental safety of their production. The main methods for nanoparticle production are chemical and physical approaches that are often costly and potentially harmful to the environment. The present review is devoted to the possibility of metal nanoparticle synthesis using plant extracts. This approach has been actively pursued in recent years as an alternative, efficient, inexpensive, and environmentally safe method for producing nanoparticles with specified properties. This review provides a detailed analysis of the various factors affecting the morphology, size, and yield of metal nanoparticles. The main focus is on the role of the natural plant biomolecules involved in the bioreduction of metal salts during the nanoparticle synthesis. Examples of effective use of exogenous biomatrices (peptides, proteins, and viral particles) to obtain nanoparticles in plant extracts are discussed.

/pdf/green-nanotechnologies-synthesis-of-metal-nanoparticles-3k69j181mp.pdf

"Green" nanotechnologies: synthesis of metal nanoparticles using plants

Plant extract synthesized silver nanoparticles: An ongoing source of novel biocompatible materials

In recent years, the progress of efficient green chemistry approaches for the fabrication of commercially viable noble metallic nanoparticles has become a major focus of researchers. The present review has focused on the various plant-mediated nanoparticle fabrication approaches, with brief discussions on the categories of various plant-mediated synthesis approaches and mechanistic aspects of plant-mediated nanoparticle synthesis. The review also focused on the commercial applications of plant-mediated noble metal nanoparticles. Significant remarks on the limitations of plant-mediated fabrication approaches with prospective future direction are also examined.

Noble Metal Nanoparticles: Plant-Mediated Synthesis, Mechanistic Aspects of Synthesis, and Applications

The green synthesis (GS) of different metallic nanoparticles (MNPs) has re-evaluated plants, animals and microorganisms for their natural potential to reduce metallic ions into neutral atoms at no expense of toxic and hazardous chemicals. Contrary to chemically synthesized MNPs, GS offers advantages of enhanced biocompatibility and thus has better scope for biomedical applications. Plant, animals and microorganisms belonging to lower and higher taxonomic groups have been experimented for GS of MNPs, such as gold (Au), silver (Ag), copper oxide (CuO), zinc oxide (ZnO), iron (Fe2O3), palladium (Pd), platinum (Pt), nickel oxide (NiO) and magnesium oxide (MgO). Among the different plant groups used for GS, angiosperms and algae have been explored the most with great success. GS with animal-derived biomaterials, such as chitin, silk (sericin, fibroin and spider silk) or cell extract of invertebrates have also been reported. Gram positive and gram negative bacteria, different fungal species and virus particles have also shown their abilities in the reduction of metal ions. However, not a thumb rule, most of the reducing agents sourced from living world also act as capping agents and render MNPs less toxic or more biocompatible. The most unexplored area so far in GS is the mechanism studies for different natural reducing agents expect for few of them, such as tea and neem plants. This review encompasses the recent advances in the GS of MNPs using plants, animals and microorganisms and analyzes the key points and further discusses the pros and cons of GS in respect of chemical synthesis.

/pdf/biological-synthesis-of-metallic-nanoparticles-plants-384c2z8cqk.pdf

Biological synthesis of metallic nanoparticles: plants, animals and microbial aspects

Nanoparticle synthesis using microorganisms and plants by green synthesis technology is biologically safe, cost-effective, and environment-friendly. Plants and microorganisms have established the power to devour and accumulate inorganic metal ions from their neighboring niche. The biological entities are known to synthesize nanoparticles both extra and intracellularly. The capability of a living system to utilize its intrinsic organic chemistry processes in remodeling inorganic metal ions into nanoparticles has opened up an undiscovered area of biochemical analysis. Nanotechnology in conjunction with biology gives rise to an advanced area of nanobiotechnology that involves living entities of both prokaryotic and eukaryotic origin, such as algae, cyanobacteria, actinomycetes, bacteria, viruses, yeasts, fungi, and plants. Every biological system varies in its capabilities to supply metallic nanoparticles. However, not all biological organisms can produce nanoparticles due to their enzymatic activities and intrinsic metabolic processes. Therefore, biological entities or their extracts are used for the green synthesis of metallic nanoparticles through bio-reduction of metallic particles leading to the synthesis of nanoparticles. These biosynthesized metallic nanoparticles have a range of unlimited pharmaceutical applications including delivery of drugs or genes, detection of pathogens or proteins, and tissue engineering. The effective delivery of drugs and tissue engineering through the use of nanotechnology exhibited vital contributions in translational research related to the pharmaceutical products and their applications. Collectively, this review covers the green synthesis of nanoparticles by using various biological systems as well as their applications.

/pdf/green-synthesis-of-metallic-nanoparticles-and-their-1r2ud08dzq.pdf

Green Synthesis of Metallic Nanoparticles and Their Potential Applications to Treat Cancer.

The medicinal and physicochemical properties of nanoscale materials are strong functions of the particle size and the materials used in their synthesis. The nanoparticle shape also contributes significantly to their medicinal properties. Several shapes ranging from oval, spherical, rods, to teardrop structures may be obtained by chemical methods. Triangular and hexagonal nanoparticles have been synthesized by using a pine cone extract (PCE). Here, we report the discovery that PCE, when reacted with silver nitrate ions, yields a high percentage of thin, flat, single-crystalline nanohexagonal and nanotriangular silver nanoparticles. The nanohexagonal and nanotriangular nanoparticles appear to grow by a process involving rapid reduction with assembly at room temperature at a high pH. The nanoparticles were characterized by UV–Vis absorption spectroscopy, SEM-EDS, TEM, FTIR, and X-ray diffraction analyses. The anisotropy of the nanoparticle shape results in large near-infrared absorption by the particles. Highly anisotropic particles are applicable in various fields, including agriculture and medicine. The obtained silver nanoparticles (Ag NPs) had significant antibacterial action on both Gram classes of bacteria associated with agriculture. Because the Ag NPs are encapsulated with functional group-rich PCE, they can be easily integrated in various applications.

Pine cone-mediated green synthesis of silver nanoparticles and their antibacterial activity against agricultural pathogens

This study highlights the ability of nitrate-reducing Bacillus subtilis EWP-46 cell-free extract used for preparation of silver nanoparticles (AgNPs) by reduction of silver ions into nano silver. The production of AgNPs was optimized with several parameters such as hydrogen ion concentration, temperature, silver ion (Ag+ ion) and time. The maximum AgNPs production was achieved at pH 10.0, temperature 60 °C, 1.0 mM Ag+ ion and 720 min. The UV–Vis spectrum showed surface plasmon resonance peak at 420 nm, energy-dispersive X-ray spectroscopy (SEM–EDX) spectra showed the presence of element silver in pure form. Atomic force microscopy (AFM) and transmission electron microscopy images illustrated the nanoparticle size, shape, and average particle size ranging from 10 to 20 nm. Fourier transform infrared spectroscopy provided the evidence for the presence of biomolecules responsible for the reduction of silver ion, and X-ray diffraction analysis confirmed that the obtained nanoparticles were in crystalline form. SDS-PAGE was performed to identify the proteins and its molecular mass in the purified nitrate reductase from the cell-free extract. In addition, the minimum inhibitory concentration and minimum bactericidal concentration of AgNPs were investigated against gram-negative (Pseudomonas fluorescens) and gram-positive (Staphylococcus aureus) bacteria.

Biosynthesis of silver nanoparticles using Bacillus subtilis EWP-46 cell-free extract and evaluation of its antibacterial activity

This study reveals a green process for the production of multi-morphological silver (Ag NPs) and gold (Au NPs) nanoparticles, synthesized using an agro-industrial residue cashew nut shell liquid. Aqueous solutions of Ag+ ions for silver and chloroaurate ions for gold were treated with cashew nut shell extract for the formation of Ag and Au NPs. The nano metallic dispersions were characterized by measuring the surface plasmon absorbance at 440 and 546 nm for Ag and Au NPs. Transmission electron microscopy showed the formation of nanoparticles in the range of 5–20 nm for silver and gold with assorted morphologies such as round, triangular, spherical and irregular. Scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction analyses of the freeze-dried powder confirmed the formation of metallic Ag and Au NPs in crystalline form. Further analysis by Fourier transform infrared spectroscopy provided evidence for the presence of various biomolecules, which might be responsible for the reduction of silver and gold ions. The obtained Ag and Au NPs had significant antibacterial activity, minimum inhibitory concentration and minimum bactericidal concentration on bacteria associated with fish diseases.

Synthesis of Silver and Gold Nanoparticles Using Cashew Nut Shell Liquid and Its Antibacterial Activity Against Fish Pathogens

Personal care products (PCPs) are among the most commonly detected compounds in surface water. PCPs have used large amount of metal and metal oxide nanoparticles (NPs). In the present study an attempt was made to study the bioaccumulation and biochemical constituents changes in gill tissues of a freshwater fish labeo rohita exposed to metal and metal oxide nanoparticles in domestic wastewater collected from student hostel. The observed results suggested that the structural conformation of proteins in fish gill tissues was significantly influenced by wastewater exposure when compared to control and the uptake of various NPs in gill tissue was very high.

/pdf/bio-accumulation-and-biochemical-constituents-changes-in-t2y0h2dsar.pdf

Bio accumulation and biochemical constituents changes in gill tissues of a freshwater fish labeo rohita exposed to metal and metal oxide nanoparticles in personal care products

Mahudunan Iydroose

Papers

Pine cone-mediated green synthesis of silver nanoparticles and their antibacterial activity against agricultural pathogens

Biosynthesis of silver nanoparticles using Bacillus subtilis EWP-46 cell-free extract and evaluation of its antibacterial activity

Synthesis of Silver and Gold Nanoparticles Using Cashew Nut Shell Liquid and Its Antibacterial Activity Against Fish Pathogens

Bio accumulation and biochemical constituents changes in gill tissues of a freshwater fish labeo rohita exposed to metal and metal oxide nanoparticles in personal care products