‘Hairy’ root extracts as source for ‘green’ synthesis of silver nanoparticles and medical applications

Variability in growth and biosynthetic activity of Calendula officinalis hairy roots

Calendula officinalis is a widespread medicinal plant with a sufficiently well-studied chemical composition. Secondary metabolites synthesized by C.officinalis plants have pharmacological value for treating numerous diseases, and various types of aseptic in vitro cultures can be used as a source of these compounds. From this perspective, hairy roots attract considerable attention for the production of bioactive chemicals, including flavonoids with antioxidant activity. This paper shows the possibility of C.officinalis hairy roots obtaining with 100% frequency by Agrobacterium rhizogenes genetic transformation. Hairy root lines differed in growth rate and flavonoid content. In particular, flavonoids were accumulated in the amount of up to 6.68 ± 0.28 mg/g of wet weight. Methyl jasmonate in the concentration of 10 µM inhibited root growth to a small extent but stimulated the synthesis of flavonoids. The antioxidant activity and the reducing power increased in the roots grown in the medium with methyl jasmonate. The strong correlation of antioxidant activity and reducing power with flavonoid content was detected. The influence of extraction conditions on the content of flavonoids in the extracts and their bioactivity was determined. The potent reducing activity of extracts from hairy roots allowed the production of silver nanoparticles, which was confirmed by transmission electron microscopy.

Cell-derived nanomaterials for biomedical applications

The ever-growing use of nature-derived materials creates exciting opportunities for novel development in various therapeutic biomedical applications. Living cells, serving as the foundation of nanoarchitectonics, exhibit remarkable capabilities that enable the development of bioinspired and biomimetic systems, which will be explored in this review. To understand the foundation of this development, we first revisited the anatomy of cells to explore the characteristics of the building blocks of life that is relevant. Interestingly, animal cells have amazing capabilities due to the inherent functionalities in each specialized cell type. Notably, the versatility of cell membranes allows red blood cells and neutrophils' membranes to cloak inorganic nanoparticles that would naturally be eliminated by the immune system. This underscores how cell membranes facilitate interactions with the surroundings through recognition, targeting, signalling, exchange, and cargo attachment. The functionality of cell membrane-coated nanoparticles can be tailored and improved by strategically engineering the membrane, selecting from a variety of cell membranes with known distinct inherent properties. On the other hand, plant cells exhibit remarkable capabilities for synthesizing various nanoparticles. They play a role in the synthesis of metal, carbon-based, and polymer nanoparticles, used for applications such as antimicrobials or antioxidants. One of the versatile components in plant cells is found in the photosynthetic system, particularly the thylakoid, and the pigment chlorophyll. While there are challenges in consistently synthesizing these remarkable nanoparticles derived from nature, this exploration begins to unveil the endless possibilities in nanoarchitectonics research.

A comprehensive review on antibacterial analysis of natural extract-based metal and metal oxide nanoparticles

Pharmaceutical, food packing, cosmetics, agriculture, energy storage devices widely utilize metal and metal oxide nanoparticles prepared via different physical and chemical methods. It resulted in the release of several dangerous compounds and solvents as the nanoparticles were being formed. Currently, Researchers interested in preparing nanoparticles (NPs) via biological approach due to their unique physiochemical properties which took part in reducing the environmental risks. However, a number of microbial species are causing dangerous illnesses and are a threat to the entire planet. The metal and metal oxide nanoparticles played a significant role in the identification and elimination of microbes when prepared using natural extract. Its biological performance is thus also becoming exponentially more apparent than it was using in conventional techniques. Despite the fact that they hurt germs, their small size and well-defined shape encourage surface contact with them. The generation of Reactive Oxygen Species (ROS), weakens the bacterial cell membrane by allowing internal cellular components to seep out. The bacterium dies as a result of this. Numerous studies on different nanoparticles and their antibacterial efficacy against various diseases are still accessible. The main objective of the biogenic research on the synthesis of key metals and metal oxides (such as gold, silver, titanium dioxide, nickel oxide, and zinc oxide) using various plant extracts is reviewed in this study along with the process of nanoparticle formation and the importance of phytochemicals found in the plant extract.

Biosynthesis of Functional Silver Nanoparticles Using Callus and Hairy Root Cultures of Aristolochia manshuriensis

This study delves into the novel utilization of Aristolochia manshuriensis cultured cells for extracellular silver nanoparticles (AgNPs) synthesis without the need for additional substances. The presence of elemental silver has been verified using energy-dispersive X-ray spectroscopy, while distinct surface plasmon resonance peaks were revealed by UV-Vis spectra. Transmission and scanning electron microscopy indicated that the AgNPs, ranging in size from 10 to 40 nm, exhibited a spherical morphology. Fourier-transform infrared analysis validated the abilty of A. manshuriensis extract components to serve as both reducing and capping agents for metal ions. In the context of cytotoxicity on embryonic fibroblast (NIH 3T3) and mouse neuroblastoma (N2A) cells, AgNPs demonstrated varying effects. Specifically, nanoparticles derived from callus cultures exhibited an IC50 of 2.8 µg/mL, effectively inhibiting N2A growth, whereas AgNPs sourced from hairy roots only achieved this only at concentrations of 50 µg/mL and above. Notably, all studied AgNPs' treatment-induced cytotoxicity in fibroblast cells, yielding IC50 values ranging from 7.2 to 36.3 µg/mL. Furthermore, the findings unveiled the efficacy of the synthesized AgNPs against pathogenic microorganisms impacting both plants and animals, including Agrobacterium rhizogenes, A. tumefaciens, Bacillus subtilis, and Escherichia coli. These findings underscore the effectiveness of biotechnological methodologies in offering advanced and enhanced green nanotechnology alternatives for generating nanoparticles with applications in combating cancer and infectious disorders.

Comparative Synthesis of Silver Nanoparticles: Evaluation of Chemical Reduction Procedures, AFM and DLS Size Analysis

The size of silver nanoparticles plays a crucial role in their ultimate application in the medical and industrial fields, as their efficacy is enhanced by decreasing dimensions. This study presents two chemical synthesis procedures for obtaining silver particles and compares the results to a commercially available Ag-based product. The first procedure involves laboratory-based chemical reduction using D-glucose (C6H12O6) and NaOH as reducing agents, while the second approach utilizes trisodium citrate dehydrate (C6H5Na3O7·2H2O, TSC). The Ag nanoparticle suspensions were examined using FT-IR and UV-VIS spectroscopy, which indicated the formation of Ag particles. The dimensional properties were investigated using Atomic Force Microscopy (AFM) and confirmed by Dynamic Light Scattering (DLS). The results showed particle size from microparticles to nanoparticles, with a particle size of approximately 60 nm observed for the laboratory-based TSC synthesis approach.

Cichorium intybus L. “hairy” roots as a rich source of antioxidants and anti-inflammatory compounds

The present study aimed to determine the bioactive profile of various extracts of Cichorium intybus L. "hairy" roots. In particular, the total content of flavonoids as well as the reducing power, antioxidant and anti-inflammatory activity of the aqueous and ethanolic (70%) extracts were evaluated. The total content of flavonoids the ethanolic extract of the dry "hairy" root reached up to 121.3 mg (RE)/g, which was twofold greater than in the aqueous one. A total of 33 diverse polyphenols were identified by the LC-HRMS method. The experimental results showed a high amount of gallic (6.103 ± 0.008 mg/g) and caffeic (7.001 ± 0.068 mg/g) acids. In the "hairy" roots, the presence of rutin, apigenin, kaempferol, quercetin, and its derivatives was found in concentrations of 0.201±0.003 - 6.710±0.052 mg/g. The broad spectrum of pharmacological activities (antioxidant, anti-inflammatory, antimutagenic, anticarcinogenic, etc.) of the key flavonoids identified in the chicory "hairy" root extract was predicted by the General Unrestricted Structure-Activity Relationships algorithm based on in the substances detected in the extract. The evaluation of the antioxidant activity showed that the EC₅₀ values of the ethanol and the aqueous extracts were 0.174 and 0.346 mg, respectively. Thus, the higher ability of the ethanol extract to scavenge the DPPH radical was observed. The calculated Michaelis and inhibition constants indicated that the ethanolic extract of C. intybus "hairy" roots is an efficient inhibitor of soybean 15-Lipoxygenase activity (IC₅₀ = 84.13 ± 7.22 μM) in a mixed mechanism. Therefore, the obtained extracts could be the basis of herbal pharmaceuticals for the therapy of human diseases accompanied by oxidative stress and inflammation, including the pandemic coronavirus disease COVID-19.

Advances in Production of Hydroxycinnamoyl-Quinic Acids: From Natural Sources to Biotechnology

Hydroxycinnamoyl-quinic acids (HCQAs) are polyphenol esters formed of hydroxycinnamic acids and (-)-quinic acid. They are naturally synthesized by plants and some micro-organisms. The ester of caffeic acid and quinic acid, the chlorogenic acid, is an intermediate of lignin biosynthesis. HCQAs are biologically active dietary compounds exhibiting several important therapeutic properties, including antioxidant, antimicrobial, anti-inflammatory, neuroprotective, and other activities. They can also be used in the synthesis of nanoparticles or drugs. However, extraction of these compounds from biomass is a complex process and their synthesis requires costly precursors, limiting the industrial production and availability of a wider variety of HCQAs. The recently emerged production through the bioconversion is still in an early stage of development. In this paper, we discuss existing and potential future strategies for production of HCQAs.

Morphology-Controlled Green Synthesis of Magnetic Nanoparticles Using Extracts of 'Hairy' Roots: Environmental Application and Toxicity Evaluation

Magnetic nanoparticles (MNPs) were "green" synthesized from a FeCl3/FeSO4/CoCl2 mixture using ethanolic extracts of Artemisia tilesii Ledeb 'hairy' roots. The effect of chemical composition and reducing power of ethanolic extracts on the morphology, size destribution and other features of obtained MNPs was evaluated. Depending on the extract properties, nanosized magnetic materials of spherical (8-11 nm), nanorod-like (15-24 nm) and cubic (14-24 nm) shapes were obtained via self-assembly. Microspherical MNPs composed of nanoclusters were observed when using extract of the control root line in the synthesis. Polyhedral magnetic nanoparticles with an average size of ~30 nm were formed using 'hairy' root ethanolic extract without any additive. Studied samples manifested excellent magnetic characteristics. Field-dependent magnetic measurements of most MNPs demonstrated a saturation magnetization of 42.0-72.9 emu/g with negligible coercivity (∼0.02-0.29 emu/g), indicating superparamagnetic behaviour only for solids with a magnetite phase. The synthesized MNPs were minimally aggregated and well-dispersed in aqueous medium, probably due to their stabilization by bioactive compounds in the initial extract. The nanoparticles were tested for magnetic solid-phase extraction of copper (Cu), cadmium (Cd) and arsenic (As) pollutants in aqueous solution, followed by ICP-OES analysis. The magnetic oxides, mainly magnetite, showed high adsorption capacity and effectively removed arsenic ions at pH 6.7. The maximum adsorption capacity was ~150 mg/g for As(III, V) on the selected MNPs with cubic morphology, which is higher than that of previously reported adsorbents. The best adsorption was achieved using Fe3O4-based nanomaterials with low crystallinity, non-spherical form and a large number of surface-localized organic molecules. The phytotoxicity of the obtained MNPs was estimated in vitro using lettuce and chicory as model plants. The obtained MNPs did not exhibit inhibitory activity. This work provides novel insights on the morphology of "green" synthesized magnetic nanoparticles that can be used for applications in adsorption technologies.

Spectroscopic Study of Phytosynthesized Ag Nanoparticles and Their Activity as SERS Substrate

The affordable and scalable synthesis of noble metal nanoparticles that are biocompatible without additional functionalization steps has been a growing field of research, stimulated by numerous prospective applications of these NPs. In the case of phytosynthesized or biogenic noble metal NPs, the mechanism of NP stabilization by biomolecules contained in each particular plant extract or living organism determines the possible applications of these NPs. In this work, we investigated Ag NPs synthesized in water with plant extracts of common toothwort (Lathraea squamaria) and two species of pepper (Capsicum annuum and Capsicum chinense). From FTIR and XPS, we drew conclusions about the composition of the functional groups and molecules that stabilize NPs in each extract, such as polysaccharide compounds (pectins, cellulose, glycosides and phenolic acids). Distinct characteristic IR features of amide I and amide II proteins were observed, which are common in plant extracts, while features of amide III were not distinctly observed in our extracts. A Raman spectroscopy study revealed weak own-SERS activity of the biomolecules of the extract and high efficiency of the NPs in the enhancement of “external” analytes, such as dyes and antibodies. This is the first report of the efficient SERS application of phytosynthesized Ag NPs.

Synthesis, Properties and Bioimaging Applications of Silver-Based Quantum Dots

Ag-based quantum dots (QDs) are semiconductor nanomaterials with exclusive electrooptical properties ideally adaptable for various biotechnological, chemical, and medical applications. Silver-based semiconductor nanocrystals have developed rapidly over the past decades. They have become a promising luminescent functional material for in vivo and in vitro fluorescent studies due to their ability to emit at the near-infrared (NIR) wavelength. In this review, we discuss the basic features of Ag-based QDs, the current status of classic (chemical) and novel methods ("green" synthesis) used to produce these QDs. Additionally, the advantages of using such organisms as bacteria, actinomycetes, fungi, algae, and plants for silver-based QDs biosynthesis have been discussed. The application of silver-based QDs as fluorophores for bioimaging application due to their fluorescence intensity, high quantum yield, fluorescent stability, and resistance to photobleaching has also been reviewed.

Biosynthesis and Cytotoxic Properties of Ag, Au, and Bimetallic Nanoparticles Synthesized Using Lithospermum erythrorhizon Callus Culture Extract

The present study reports a green chemistry approach for the rapid and easy biological synthesis of silver (Ag), gold (Au), and bimetallic Ag/Au nanoparticles using the callus extract of Lithospermum erythrorhizon as a reducing and capping agent. The biosynthesized nanoparticles were characterized with ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) analysis, and transmission electron microscopy (TEM). Our results showed the formation of crystalline metal nanostructures of both spherical and non-spherical shape. Energy dispersive X-ray (EDX) spectroscopy showed the characteristic peaks in the silver and gold regions, confirming the presence of the corresponding elements in the monometallic particles and both elements in the bimetallic particles. Fourier-transform infrared (FTIR) spectroscopy affirmed the role of polysaccharides and polyphenols of the L. erythrorhizon extract as the major reducing and capping agents for metal ions. In addition, our results showed that the polysaccharide sample and the fraction containing secondary metabolites isolated from L. erythrorhizon were both able to produce large amounts of metallic nanoparticles. The biosynthesized nanoparticles demonstrated cytotoxicity against mouse neuroblastoma and embryonic fibroblast cells, which was considerably higher for Ag nanoparticles and for bimetallic Ag/Au nanoparticles containing a higher molar ratio of silver. However, fibroblast migration was not significantly affected by any of the nanoparticles tested. The obtained results provide a new example of the safe biological production of metallic nanoparticles, but further study is required to uncover the mechanism of their toxicity so that the biomedical potency can be assessed.

Biomimetic synthesis of functional silver nanoparticles using hairy roots of Panax ginseng for wheat pathogenic fungi treatment

Presently, multifunctional silver nanoparticles (AgNPs) show a rapid growth in various commercial applications, leading to increasing demand for new eco-friendly manufacturing technologies. An array of genetic engineering tools can be used to increase the yield in the production of AgNPs using various biological systems. The present study reports a green chemistry approach for the biological synthesis of AgNPs using extracts from non-transformed callus, rolC-transgenic callus and hairy roots of Panax ginseng and an evaluation of their efficacy against crop-damaging fungal pathogens. All types of ginseng cell lines promote the reduction of silver nitrate and formation of spherical AgNPs with an average diameter of 50-90 nm. Notably, hairy root extract possessed the maximal reduction potential among the studied cell lines probably due to higher secondary metabolite content. The biosynthesized nanoparticles were highly toxic against several wheat fungal pathogens including Fusarium graminearum, F. avenaceum, F. poae, and F. sporotrichioides, which are associated with fusarium head blight disease in cereals. Furthermore, the antifungal activity of nanosilver was successfully utilized for surface sterilization of infected wheat kernels without any negative effect on seed germination capability.

Biosynthesis of magnetite and cobalt ferrite nanoparticles using extracts of "hairy" roots: preparation, characterization, estimation for environmental remediation and biological application

The "green" synthesis of magnetite and cobalt ferrite nanoparticles (Fe3O4-NPs and CoFe2O4-NPs) using extracts of Artemisia annua L "hairy" roots was proposed. In particular, the effect and role of important variables in the 'green' synthesis process, including the metal-salt ratio, various counter ions in the reaction mixture, concentration of total flavonoids and reducing power of the extract, were evaluated. The morphology and size distribution of the magnetic nanoparticles (MNPs) depended on the metal oxidation state and ratio of Fe(iii) : Fe(ii) in the initial reaction mixture. MNPs obtained from divalent metal salts in the reaction mixture were non-uniform in size with high aggregation level. Samples obtained by the FeCl3/FeSO4 mixture with a ratio of Fe(iii) : Fe(ii) = 1 : 2 showed an irregular shape of the nanoparticles and high aggregation level. MNPs obtained by the FeCl3/FeSO4/CoCl2 mixture showed a regular shape with slight aggregation, and were in the nanosize range (10-17 nm). Thus, this mixture as a metal-precursor was used for MNP biosynthesis in the subsequent experiments. The XRD data showed that the magnetic specimens contained mainly spinel type phase. The data of EDX and XPS analysis indicated that the product of the "green" synthesis was magnetite with some impurities, owing to the obtained ratio of Fe : O being similar to the theoretical atomic ratio of magnetite (3 : 4). The Fe3O4-NP samples were superparamagnetic with high magnetization (until 68 emu g-1). The Co-containing MNPs demonstrated low ferromagnetic properties. The MNPs with pure magnetite phase, very good magnetization and uniform size distribution (ca. 12-14 nm) were prepared by the "hairy" root extract characterized by the highest amount of total flavonoids. According to the FTIR data, the synthesized Fe3O4-NPs had a core-shell like structure, in which the core was composed of Fe3O4, and the shell was formed by bioactive molecules. The presence of several organic compounds (such as flavonoids or carboxylic acids) plays a key role in the suppression of Fe3O4-NP aggregation without addition of a stabilizing agents. Synthesized Fe3O4-NP samples effectively removed Cu(ii) and Cd(ii) with the maximum adsorption capacity, reaching 29.9 mg g-1 and 33.5 mg g-1, respectively. It is probable that the presence of organic components in extracts plays an important role in the adsorption properties of biosynthesised MNPs. The obtained MNPs were successfully applied to the removal of heavy metal ions in the environmental water samples. Fe3O4-NPs also negatively affected plant growth in the case of using "hairy" roots as a test model, and the greatest inhibitory activity (99.56 wt%) was possessed by MNPs with high magnetic properties.