The past decade has witnessed a phenomenal rise in nanotechnology research due to its broad range of applications in diverse fields including food safety, transportation, sustainable energy, environmental science, catalysis, and medicine. The distinctive properties of nanomaterials (nano-sized particles in the range of 1 to 100 nm) make them uniquely suitable for such wide range of functions. The nanoparticles when manufactured using green synthesis methods are especially desirable being devoid of harsh operating conditions (high temperature and pressure), hazardous chemicals, or addition of external stabilizing or capping agents. Numerous plants and microorganisms are being experimented upon for an eco–friendly, cost–effective, and biologically safe process optimization. This review provides a comprehensive overview on the green synthesis of metallic NPs using plants and microorganisms, factors affecting the synthesis, and characterization of synthesized NPs. The potential applications of metal NPs in various sectors have also been highlighted along with the major challenges involved with respect to toxicity and translational research.

Green Synthesis of Metallic Nanoparticles: Applications and Limitations

The cornerstone of nanoscience and nanotechnology are nanoparticles which have immense power and functional ability in diverse fields. Nanoparticles are synthesized by physical, chemical methos but limitations are due to its toxicity. We have discussed few green synthesis routes which are eco friendly and less toxic methods, including alage, microorganisms, plants etc.. Expoiting the potential of medicinal plants, is one of the green synthesis routes and is significant because the current therapeutic approaches have toxicity problems and microbial multidrug resistance issues. As the metal nanoparticles have received great attention across the globe, so in this study we have discussed and focused many different metallic nanoparticles obtained by green synthesis using medicinal plants. We have also discussed the types, size and medicinal properties like antibacterial, antifungal, anticancer, antiviral activities of nanoparticles. The biomolecules, secondary metabolites and coenzymes present in the plants help in easy reduction of metal ions to nanoparticles. Such nanoparticles are considered as potential antioxidants and promising candidates in cancer treatment. The simplified model summarises the green synthesis, its characterization using physicochemical means and their biomedical applications. Succinctly, we have discussed the recent advances in green synthesis of metallic nanoparticles, milestones, therapeutic applications and future perspectives of biosynthesized nanoparticles from some important medicinal plants.

Medicinal plants: Treasure trove for green synthesis of metallic nanoparticles and their biomedical applications

Plant-mediated green synthesis of nanoparticles is an eco-friendly and cheap method since it makes use of phyto-compounds present in various plant parts as reducing and stabilizing agents. Herein, magnetic, ferric oxide nanoparticles (FONPs) were prepared by utilizing the leaf extract of Peltophorum pterocarpum for the first time. Rod-like FONPs with agglomerations were witnessed in FE-SEM images. Sharp peaks for elemental oxygen and iron were witnessed in EDS spectrum. XRD spectrum ascertained the crystallinity of the FONPs and showed both γ and α–Fe 2 O 3 phases. The average crystallite size was 16.99 nm. A large specific surface area (66.44 m 2 /g) was found in BET analysis and the FONPs were mesoporous (pore diameter = 7.92 nm). TGA results showed a 20% weight loss during heating up to 800 °C. FTIR spectrum showed significant bands for various phyto-compounds and Fe–O. The Fenton-like catalytic efficiency of FONPs was studied for the methylene blue dye degradation during which 90% removal was noticed within 220min. The experimental results were satisfactorily fitted into a second-order model with a degradation constant of 0.0987 L/mg min. Also, the catalytic activity of the FONPs was assessed for the removal of MB dye with the reducing agent NaBH 4 . A remarkable dye degradation (92%) was attained within 27min, and the results were best suited for a first-order model with a kinetic degradation constant of 0.0856min −1 . Therefore, the green-synthesized FONPs obtained here could be used in the degradation of dyes as nanocatalysts for the remediation of wastewater.

Biogenic synthesis of ferric oxide nanoparticles using the leaf extract of Peltophorum pterocarpum and their catalytic dye degradation potential

Nanotechnology is increasingly used in food science, and one of the lines of research is the nanoencapsulation of bioactive compounds. While these compounds promote improvements in human health, they are often improperly absorbed. Thus, nanostructured systems improve several characteristics, such as protection against degradation, solubility, stability, and bioavailability, among others. However, the development of nanostructures faces many challenges, from choosing the best method to obtain them to identifying the type of nanomaterial ideal for a bioactive compound of interest. In addition, the characterization of toxicological effects is sought by specific regulation for safety in human consumption and the environment, such as the use of green synthesis.

Nanoencapsulation of bioactive compounds: challenges and perspectives

Here, the various types of naturally synthesized metallic nanoparticles, which are essentially composed of Ce, Ag, Au, Pt, Pd, Cu, Ni, Se, Fe, or their oxides, are presented, based on a literature analysis The synthesis methods used to obtain them most often involve the reduction of metallic ions by biological materials or organisms, ie, essentially plant extracts, yeasts, fungus, and bacteria The anti-tumor activity of these nanoparticles has been demonstrated on different cancer lines They rely on various mechanisms of action, such as the release of chemotherapeutic drugs under a pH variation, nanoparticle excitation by radiation, or apoptotic tumor cell death Among these natural metallic nanoparticles, one type, which consists of iron oxide nanoparticles produced by magnetotactic bacteria called magnetosomes, has been purified to remove endotoxins and abide by pharmacological regulations It has been tested in vivo for anti-tumor efficacy For that, purified and stabilized magnetosomes were injected in intracranial mouse glioblastoma tumors and repeatedly heated under the application of an alternating magnetic field, leading to the full disappearance of these tumors As a whole, the results presented in the literature form a strong basis for pursuing the efforts towards the use of natural metallic nanoparticles for cancer treatment first pre-clinically and then clinically

https://www.mdpi.com/1422-0067/21/12/4412/pdf

Natural Metallic Nanoparticles for Application in Nano-Oncology.

Medicinal plants are of great importance in traditional medicine, in which in most part, the antioxidant activity of the plant-derived compounds is imagined responsible for treating various diseases. Rosmarinus officinalis L, contains several polyphenolic compounds with antioxidant activity; However, to elicit the anti-proliferative activity of R. officinalis, it is required to be improved via different strategies. Nowadays, green synthesis of metal nano- particles involving plant extract has attracted the attention of many researchers as this approach could help to derive the therapeutic benefits of the plant extracts. In this study, for the first time, the aqueous extract of rosemary was applied in green iron nanoparticle platform (Rosemary-FeNPs). Various methods, including dynamic light scattering(DLS), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Transmission electron microscopy (TEM), and Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) were employed to characterize Rosemary-FeNPs. The mean size of the Rosemary-FeNPs were at about 100 nm with PDI of less than 0.12, which indicates a homogeneous size distribution of the nanoparticles. The cytotoxicity of Rosemary-FeNPs and total extract of rosemary was determined using MTT cytotoxic test on 4T1 and C26 cancer cell lines. The results showed that Rosemary-FeNPs could exert more cytotoxic effect than total extract on both cancer cell lines.

Green synthesis of iron nanoparticles by Rosemary extract and cytotoxicity effect evaluation on cancer cell lines

The therapeutic potential of targeting CD73 and CD73-derived adenosine in melanoma.

Synthesis and characterization of nanoliposome containing Fe2+ element: A superior nano-fertilizer for ferrous iron delivery to sweet basil

A novel and easy to prepare azo-based bioreductive linker and its application in hypoxia-sensitive cationic liposomal doxorubicin: synthesis, characterization, in vitro and in vivo studies in mice bearing C26 tumor.

Helale Kaboli Farshchi

Papers

Green synthesis of iron nanoparticles by Rosemary extract and cytotoxicity effect evaluation on cancer cell lines

The therapeutic potential of targeting CD73 and CD73-derived adenosine in melanoma.

Synthesis and characterization of nanoliposome containing Fe2+ element: A superior nano-fertilizer for ferrous iron delivery to sweet basil

A novel and easy to prepare azo-based bioreductive linker and its application in hypoxia-sensitive cationic liposomal doxorubicin: synthesis, characterization, in vitro and in vivo studies in mice bearing C26 tumor.