Eco-friendly synthesis of CuO nanoparticles with Tabernaemontana divaricata leaf extract: Impact on structural and magnetic properties for biomedical applications

Synthetic synthesis of nanoparticles is harmful to human and environment due to pollution. The use of harmful chemicals in synthetic method has avoided in the biosynthesis. To overcome the hurdles in synthesis of nanoparticles, the biogenic synthesis of CuO nanoparticles has been done with Plectranthus amboinicus leaf extracts. The biosynthesis provides the enhanced efficiency compared to synthetic methods. It establishes the environmentally friendly and pollution-free approach. The powder X-ray diffraction (XRD) pattern exhibited a crystalline nature with the crystallite size in 20–35 nm. The Fourier-Transform InfraRed (FTIR) spectrum explicated the Cu and O metal oxide bonds. The UV–visible analysis emphasized the stability of CuO nanoparticles with the inference of the Surface Plasmon Resonance band at 398 nm. The photoluminescence study displayed the bluish–green emission nature peak at 491 nm. The particle size analyzer manifested the synthesized CuO nanoparticles majority in 5–40 nm. The field-emission scanning electron micrographs (FESEM) and high-resolution transmission electron micrographs (HRTEM) exposed the spherical, circular-shaped nanoparticles with size in 5–30 nm range. The energy dispersive X-ray diffraction (EDAX) spectrum and mapping proved the CuO nanoparticles formation. The antimicrobial activity reported the potent nature of formed CuO nanoparticles on bacteria and fungi. The antioxidant activity identified the effective free-radical scavenging activity nature at 95% in 80 μg/mL and IC50 value at 40.10 μg/mL concentration. The anti-inflammatory activity assessed the efficient nature of CuO nanoparticles in protein denaturation of Egg albumin at 92% in 500 μg/mL and IC50 value at 243.08 μg/mL concentration. The anti-diabetic activity established the effective inhibition on α-Amylase at 94% in 500 μg/mL and IC50 value at 317.19 μg/mL concentration. The anti-larvicidal activity manifested the potent inhibition on Anopheles subpictus mosquito larvae within 24 h in 100 ppm concentration and which exhibited low LC50 value.

Silver nanomaterials have been integrated into industrial, biomedical and agricultural application, including biosensor, anti-microbial, anti-tumor, drug delivery, waste treatment, coated fabrics and nano fertilizer. Nanoparticle possesses unusual character due to their large surface area to volume ratio and an extraordinary catalytic activity, electronic properties, optical properties and anti-microbial activity while they are constructed in atomic level. The unique and major task in the synthesis of nanoparticle is choosing of an advanced and ecofriendly method. Nevertheless, physical and chemical methods of synthesis of nanoparticles are too expensive and environmentally unsound. In this study, the green synthesis of nanoparticle’s production methods was evaluated on the basis of variable literatures. Currently, there is a better possibility of using green synthesis of silver nanoparticles, especially a plant, bacterial and fungal production of nanoparticles which is emerging as a novel ecofriendly technique. The growth rate of bacterial culture, the extract of plant secondary metabolite and mycelial surface area of fungus are the main comprehensible mechanism in green synthesis of silver nanoparticles. The silver nanoparticles, which are produced through green biosynthesis is safe and hold a better possibility to be administered for medical and agricultural usages. Over all we found that the fungal green biosynthesis of silver nanoparticles is considered more preferable and is excellently chosen in it in industrial level production.

One of the most important criteria of nanotechnology is the development of clean, nontoxic, and environmentally acceptable ''green chemistry'' procedures, involving organisms ranging from bacteria to fungi. The interactions between microbes and metals have been well documented and the ability of microorganisms to extract and accumulate metals is already employed in biotechnological processes such as bioleaching and bioremediation. The synthesis of chemical, photoelectrochemical, and electronic properties enables the synthesis of nanoparticles of different chemical compositions, well-defined sizes, and distinct morphologies. It is well known that many organisms can synthesize inorganic materials either intra- or extracellularly. The biological synthesis of nanoparticles is easy, efficient, and eco-friendly in comparison to chemical or physical synthesis. Physical and chemical synthesis procedures involve toxic solvents as well as high pressure, energy, and temperature, so in biological synthesis the best option is the synthesis of nanoparticles using microbes. The use of fungi in the synthesis of nanoparticles is a relatively recent addition to the list of microorganisms possessing nanoparticle biosynthesis "ability". The application of fungi to produce nanoparticles is potentially exciting because of their ability to secrete large amounts of enzymes. In comparison with other microbial syntheses, the fungal synthesis of silver nanoparticles (AgNPs) is very easy to handle at laboratory scale and fungi do contain larger proteins in their cell walls. Moreover, it is easy to harvest the mycelia. Nanomedicine is a burgeoning field of research with tremendous prospects for the improvement of the diagnosis and treatment of human diseases. Research is carried out in manipulating microorganisms at the genomic and proteomic levels. With the recent progress and the ongoing efforts in improving particle synthesis efficiency and exploring their biomedical applications, we are hopeful that the implementation of these approaches on a large scale and their commercial applications in medicine and healthcare will take place in the coming years.

Synthesis of nanoparticles with unique properties has attracted a lot of interest of scientists and researchers these days. A key aspect of being able to manipulate the properties of the nanomaterials is the nanoscale architecture and engineering by various processing techniques. A synthetic strategy was developed to control the preparation of nickel nanoparticles Ni-NPs produced using an arc discharge technique with an ultrasonic nebulizer. The sample was characterized for its structural and magnetic properties using X-ray diffraction, ultraviolet–visible (UV–Vis) spectrophotometer, zeta potential, high resolution transmission electron microscope, scanning electron microscope, vibrating sample magnetometer. The resulted sample unveiled small, spherical and homogeneous Ni nanoparticles with an average size 15 nm lower than the critical size which indicates a superparamagnetic behavior. The zeta potential measurements shows + 49.01 ± 3.2 mV which confirms the synthesis of stable Ni nanoparticles. A UV–Vis spectrum of the nanosized Ni sample shows a sharp absorption peak between 362 and 380 nm. The magnetic properties shows no hysteresis and zero results for coercivity force and remanence that indicates superparamagnetic behavior of the Ni nanoparticles.

In recent years, there has been an increasing interest in the development of plant‐based nanoparticles due to their numerous benefits over conventional physio‐chemical methods, including sustainability and environmental safety. Green synthesis, a process that produces safe and sustainable goods without the use of harsh chemicals or other harmful processes, is gaining popularity. The current study focuses on the green synthesis of copper oxide nanoparticles using Piper nigrum leaf extracts, their characterization, and applications. The synthesis of nanoparticles was confirmed by changes in colour, further endorsed by UV–visible spectroscopy. Copper oxide (CuO) nanoparticles were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). CuO nanoparticle sizes ranged between 58.23 and 69.89 nm and were spherical in shape. FTIR results indicated a functional group capped on the nanoparticle surface. The antibacterial activity of the copper oxide nanoparticles was tested, and they exhibited the significant decrease in bacterial concentration and the largest zone of inhibition, making them an efficient disinfectant. Antimicrobial activity against Bacillus subtilis and Escherichia coli was observed. Furthermore, the synthesized CuO nanoparticles exhibited a high affinity for safranin dyes and demonstrated maximum removal efficiency. This makes them an effective agent for removing dyes in wastewater from industries such as clothing manufacturing. Safranin dye was successfully removed with an efficiency of 78% using nanoparticles. In conclusion, the green synthesis of copper oxide nanoparticles using plant extracts presents an eco‐friendly and sustainable approach for producing nanoparticles with a wide range of potential applications.

Chapter 3 - Green synthesis of phytogenic nanoparticles

The synthesis of biogenic nanoparticles from readily available natural resources may have large demand in numerous fields including pharmaceuticals and medicine. The biogenic nanoparticles catch the attention of the scientific community due to their low cytotoxicity and biocompatibility. Chemical, physical, and greener methods are used for the synthesis of biogenic nanoparticles. Researchers used eco-friendly and nontoxic approaches in the synthesis of this nanoparticle. This nanomaterial-based medicine plays a vital role in the management of public health, including earlier detection of disease, therapeutics candidates in the treatment of cancer. Biogenic nanocomposites are environmentally benign candidates that include fabrication of various composites, detoxification, and act as a catalyst in the biodegradation process. In this review article, we emphasize the recently reported methods used for synthesis, summarizing their biomedical applications and commercial and environmentally benign applications. Synthetic strategies include greener, chemical, physical, and biogenic methods and their role in surface modifiers involves various biomedical, commercial, and environmental-related applications. Moreover, we glimpse existing status, key contests, and future perspectives.

Nanoparticles have distinct properties that make them potentially valuable in a variety of industries. As a result, emerging approaches for the manufacture of nanoparticles are gaining a lot of scientific interest. The biological pathway of nanoparticle synthesis has been suggested as an effective, affordable, and environmentally safe method. Synthesis of nanoparticles through physical and chemical processes uses unsafe materials, expensive equipment and adversely affects the environment. As a result, in order to support the increased utilization of nanoparticles across many sectors, nanotechnology research activities have shifted toward environmentally safe and cost-effective techniques that outperform chemical and/or biological procedures. The use of organisms to produce metal nanoparticles is among the most frequently discussed methods. Plants appear to be the best candidates among these organisms for large-scale nanoparticle biosynthesis. Medicinal plants have been employed as reducing agents and NP stabilizers to minimize the toxicity of NPs in both the environment and the human body. Furthermore, the presence of certain functional components in plant extracts may be extremely useful and effective for the human body. Polyphenol, for example, which may have antioxidant properties, might intercept free radicals before they interact with other biomolecules and cause considerable damage. The current article analyzes the most recent developments and improvements in the green synthesis of metal nanoparticles by different plants and the use of these nanoparticles for various biomedical applications and hopes to provide insights into this exciting research frontier.

The magnetic-field-assisted synthesis of the Co-ferrite nanoparticles via reverse co-precipitation and their magnetic and structural properties

In this work, we have reported, a cost effective and environment friendly technique for the synthesis of ZnO and CuO nanoparticles using ferulago angulata (schlecht) boiss extract as a mild and non-toxic reducing agent and efficient stabilizer without adding any surfactants. The secondary metabolites, ubiquitously found in plants have a significant role in synthesis of nanoparticles. As-synthesized metal oxides nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission-scanning electron microscopy. X-ray diffraction results revealed that the biosynthesized ZnO NPs and CuO NPs were crystalline in nature with higher purity and particle size of ~ 44 nm. In addition, the photocatalytic degradation activity of ZnO and CuO photocatalyst were evaluated using Rhodamine B as organic contaminant irradiated only with visible light from fluorescent lamp. Catalytic reactions were monitored by using UV–Vis spectrophotometer. This study indicates photocatalytic degradation capacity of the ZnO NPs was higher than CuO NPs.

Sustainable green synthesis of silver nanoparticles using Sambucus ebulus phenolic extract (AgNPs@SEE): Optimization and assessment of photocatalytic degradation of methyl orange and their in vitro antibacterial and anticancer activity

In this study, it was investigated the effects of the used fuels on structural, morphological and magnetic properties of nanoparticles in nanoparticle synthesis with microwave assisted combustion method with an important method in quick, simple and low cost at synthesis of the nanoparticles. In this aim, glycine, urea and citric acid were used as fuel, respectively. The synthesised nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and vibrating sample magnetometry (VSM) techniques. We observed that fuel type is quite effective on magnetic properties and surface properties of the nanoparticles. X-ray difractograms of the obtained nanoparticles were compared with standard powder diffraction cards of NiFe2O4 (JCPDS Card Number 54-0964). The results demonstrated that difractograms are fully compatible with standard reflection peaks. According to the results of the XRD analysis, the highest crystallinity was observed at nanoparticles synthesized with glycine. The results demonstrated that the nanoparticles prepared with urea has the highest surface area. The micrographs of SEM showed that all of the nanoparticles have nano-crystalline behaviour and particles indication cubic shape. VSM analysis demonstrated that the type of fuel used for synthesis is highly effective a parameter on magnetic properties of nanoparticles.

Currently, synthesis of nanoparticles from several noble metals like palladium, tin, copper, silver and gold etc. has received more attention because of their unique properties as well as their application in different fields. Furthermore, silver nanoparticles play an important role in pharmaceutical industries because they function like antibacterial agents which carry less toxic effects. In case of industrial applications, silver particles (inkjet inks) having regular dispersions are helpful in making different electronic circuits. Over the period, various synthetic methods for the synthesis of silver nanoparticles were reported i.e. physical, chemical, and photochemical. However, most of the available techniques are expensive and not eco-friendly i.e. environmentally harmful. There are various factors such as the methods of synthesis, temperature, dispersing agent, surfactant etc. which greatly influence the quality and quantity of the synthesized nanoparticles and ultimately affect their properties. It is also pertinent to mention here that the main target for these silver nanoparticles was not only to synthesize in nano range, but also require easy, eco-friendly and economical synthesis of the nanoparticles. Therefore, this review mainly goes through the several methods of synthesis of nanoparticles which should be based on the green approach, and easy to be synthesized at low cost. In addition, we also discussed some approaches to fabricate silver-based nanoparticles, their enhanced properties and their different type of applications such as electrical conductivity, antibacterial, optical, photocatalytic properties.

Biological synthesis of α-Ag2S composite nanoparticles using the fungus Humicola sp. and its biomedical applications

The marine ecosystem has captured a major attention in recent years since various biologically active compounds have been isolated and screened for pharmacological activity from dissimilar marine provenience. Marine biological resources can be considered an essential for nanotechnology, researchers had been interested to synthesize metallic nanoparticles from marine source because it is thought to be ecofriendly, nontoxic, environmentally acceptable ‘‘green procedures”, reduces the down-streaming process making it very cost effective and the availableness of the source from the diverse marine ecosystem becomes a much easier task. The biosynthesized nanoparticles from marine compound offer stabilized nanoparticles through compounds present in the marine source that make them more efficient for both biomedical and industrial applications[1]. 
\nIn this regard, we have focus our attention in two algae of Cystoseira. It is a genus of marine brown macroalgae composed of about 40 species. It is widely distributed in the North East Atlantic, the Baltic Sea and the Mediterranean. This genus contains a wide variety of secondary metabolites (e.g. terpenoids, steroids, phlorotannins, phenolic compounds, carbohydrates, triacylglycerols/fatty acids, pigments, vitamins) that are associated with pharmacological properties, such as antioxidant, anti-inflammatory, cytotoxicity, anticancer, cholinesterase inhibition and anti-diabetic activities but also antibacterial, antifungal and anti-parasitic activities [2]. Cystoseira baccata (CB) and Cystoseira tamariscifolia (CT) are two species of this genus that differ in geographic distribution, morphology and possibly content of secondary metabolites. 
\nGold nanoparticles are presently under intensive study since they can be the remarkable scaffold for novel biological and chemical applications owing to their unique electrical, chemical and optical properties. Such as their easy synthesis and good biocompatibility due to the low reactivity of the golden core. Therefore presenting potential applications in the development of new technologies in different fields such as in the food, cosmetic and pharmaceutical industry [3,4]. 
\nPreviously, González-Ballesteros et al have reported the synthesis of gold nanoparticles with antitumor activity led by the macroalga CB [5]. In the present study, we have compared the ability of C. baccata and C. tamariscifolia (CT) in the synthesis of gold nanoparticles. With this aim, aqueous extracts of the two macroalgae were prepared and their reducing activity, total phenolic content and DPPH scavenging activity were determined before and after the synthesis of nanoparticles. Results showed that CT possess three times more reducing power, almost 4 times more phenolic content and 4 time more DPPH scavenging activity than CB. The nanoparticles obtained were characterized by UV-Vis spectroscopy and Transmission electron microscopy confirming the formation of spherical nanoparticles with a mean diameter of 8.4 ± 2.2 nm in the case of Au@CB and 7.6 ± 2.2 nm for Au@CT.
\nIn order to compare the biological potential of both CT and CB extracts and their respective gold nanoparticles (Au@CT and Au@CB), it was investigated whether they affect the viability in mouse (L929 cell line) and human (BJ5-ta cell line) fibroblast cells as in vitro models, by evaluating cellular metabolism by tetrazolium-based colorimetric cellular assay (MTT); cell membrane integrity by lactate dehydrogenase activity (LDH); wound-healing assay to asses effects on cell proliferation and migration capacity. Both algae extracts and derived nanoparticles present a non-cytotoxic profile in lower concentrations, which are efficient in cell regeneration, although with some differences between both species.
\nFor a correlation between in vitro and in vivo toxicity, the zebrafish embryo toxicity (ZET) assay, recomended by OECD to evaluate acute and chronic toxicity, was performed. This model organism has a translucent body, allowing real time observation, and allows the evaluation of whole organism responses, from mortality to more specific parameters such as neurotoxicity. The results show that toxicity is evident only at very high concentrations. 
\nThese promising results thus support that green synthesis in CB and CT extracts of non-toxic, bioactive nanoparticles have an interesting potential for biomedical applications.