Identification of active biomolecules in the high-yield synthesis of single-crystalline gold nanoplates in algal solutions

Green synthesis of gold nanoparticles in an animal model of chronic wound induced with Resiquimod

Cost-effective strategies for the treatment of chronic wounds must be developed. The green synthesis of gold nanoparticles (GNPs) it is possible to guarantee a lower toxicity in biological tissues and greater safety of applicability, in addition to adding the effects of nanoparticles (NPs) to those of extracts. The objective of this study was to evaluate the effects of treatment with biosynthesized GNPs in a chronic wound model. Wistar rats were distributed into 7 groups: Acute Wound (AW); Chronic wound (CW); CW + GNPs-Açaí; CW + GNPs-DB; CW + AV-GNPs; CW + SafGel®; CW + 660 nm laser. The chronic injury model was induced with topically applied Resiquimod for 6 days. Treatments were then initated on the fourteenth day after the last application of Resiquimod and carried out daily for ten days. The proposed therapies with GNPs were able to significantly reduce the inflammatory score and increase the rate of wound contraction. In histology, there was a reduction in the inflammatory infiltrate and increased gene expression of fibronectin and type III collagen, mainly in the CW + AV-GNPs group. The therapies were able to reduce pro-inflammatory cytokines, increase anti-inflammatory cytokines, and reduce oxidative stress. The results demonstrated that the effects of GNPs appear to complement those of the extracts, thereby enhancing the tissue repair process.

The impact of pH and temperature on the green gold nanoparticles preparation using Jeju Hallabong peel extract for biomedical applications

The utilization of gold nanoparticles (AuNPs) has garnered significant attention in recent times, particularly in the field of biomedical research. The utilization of AuNPs in chemical synthesis procedures raises apprehensions regarding their potential toxicity in living organisms, which is inconsistent with their purported eco-friendly and cost-effective aspects. In this investigation, AuNPs were synthesized via the green synthesis approach utilizing Jeju Hallabong peel extract (HPE), a typical fruit variety indigenous to South Korea. The visible-range absorption spectrum of gold nanoparticles from green synthesis (HAuNPs) that are red wine in color occurs at a wavelength of λ = 517 nm. The morphology and particle size distribution were analysed using transmission electron microscopy (TEM) and ImageJ software. The TEM images reveal that the HAuNPs exhibit a high degree of dispersion and uniformity in their spherical shape, with an average size of approximately 7 nm. Moreover, elevating the initial pH level of the mixed solution has an impact on the decrease in particle dimensions, as evidenced by the blue shift observed in the UV-visible spectroscopy absorbance peak. Elevating the reaction temperature may accelerate the synthesis duration. However, it does not exert a substantial impact on the particle dimensions. The outcomes of an avidin-biocytin colorimetric assay provide preliminary analyses of possible sensor tunability using HAuNPs. The cytotoxicity of HAuNPs was evaluated through in vitro studies using the MTT assay on RAW 264.7 cell lines. The results indicated that the HAuNPs exhibited lower cytotoxicity compared to both chemically reduced gold nanoparticles (CAuNPs).

Green synthesis of reduced graphene oxide by using tropical microalgae and its application in biophotovoltaic devices

The successful commercialization of algal biophotovoltaics (BPV) technology hinges upon a multifaceted approach, encompassing factors such as the development of a cost-efficient and highly conductive anode material. To address this issue, we developed an environmentally benign method of producing reduced graphene oxide (rGO), using concentrated Chlorella sp. UMACC 313 suspensions as the reducing agent. The produced rGO was subsequently coated on the carbon paper (rGO-CP) and used as the BPV device's anode. As a result, maximum power density was increased by 950% for Chlorella sp. UMACC 258 (0.210 mW m-2) and 781% for Synechococcus sp. UMACC 371 (0.555 mW m-2) compared to bare CP. The improved microalgae adhesion to the anode and improved electrical conductivity of rGO brought on by the effective removal of oxygen functional groups may be the causes of this. This study has demonstrated how microalgal-reduced GO may improve the efficiency of algal BPV for producing bioelectricity.

Characterization and Eco-Friendly Synthesis of Silver and Iron Nanoparticles Using Microalgae Extracts: Implications for Nanobiotechnology

<b>Background and Objective:</b> The remarkable surface-to-volume ratio and efficient particle interaction capabilities of nanoparticles have garnered significant attention among researchers. Microalgal synthesis presents a sustainable and cost-effective approach to nanoparticle production, particularly noteworthy for its high metal uptake and ion reduction capabilities. This study focuses on the eco-friendly and straightforward synthesis of Silver (AgNPs) and Iron (FeNPs) nanoparticles by utilizing Spirulina (<i>Arthrospira platensis</i>) and <i>Chlorella pyrenoidosa</i> extract, devoid of any chemical reducing or capping agents. <b>Materials and Methods:</b> Following the mixing of 1 mM AgNO₃ and 1 mM iron oxide solution with the algal extract, the resulting filtrated solution underwent comprehensive characterization, including UV-visible absorption spectra analysis, observation of particle morphology, Zetasizer measurements and Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) analysis. <b>Results:</b> The UV-visible spectroscopy revealed a maximum absorbance peak at 430-440 nm, confirming the successful green synthesis of AgNPs and FeNPs, as indicated by the distinct color change from transparent to dark reddish-yellow and brown to reddish-brown, respectively. The SEM-EDX analysis further elucidated the spherical morphology of the nanoparticles, with an average diameter of 93.71 nm for AgNPs and 6198 nm for FeNPs. The Zeta potential measurements indicated average values of -56.68 mV for AgNPs and 29.73 mV for FeNPs, with conductivities of 0.1764 and 0.6786 mS/cm, respectively. <b>Conclusion:</b> The observed bioaccumulation of silver and iron nanoparticles within the algal extract underscores its potential as an environmentally friendly and cost-effective method for nanoparticle synthesis. These findings suggested a promising avenues for the application of silver and iron nanoparticles in the field of nanobiotechnology. Future research endeavors could focus on optimizing preparation conditions and controlling nanoparticle size to further enhance their utility and effectiveness.

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.

How Synthesis of Algal Nanoparticles Affects Cancer Therapy? - A Complete Review of the Literature

The necessity to engineer sustainable nanomaterials for the environment and human health has recently increased. Due to their abundance, fast growth, easy cultivation, biocompatibility and richness of secondary metabolites, algae are valuable biological source for the green synthesis of nanoparticles (NPs). The aim of this review is to demonstrate the feasibility of using algal-based NPs for cancer treatment. Blue-green, brown, red and green micro- and macro-algae are the most commonly participating algae in the green synthesis of NPs. In this process, many algal bioactive compounds, such as proteins, carbohydrates, lipids, alkaloids, flavonoids and phenols, can catalyze the reduction of metal ions to NPs. In addition, many driving factors, including pH, temperature, duration, static conditions and substrate concentration, are involved to facilitate the green synthesis of algal-based NPs. Here, the biosynthesis, mechanisms and applications of algal-synthesized NPs in cancer therapy have been critically discussed. We also reviewed the effective role of algal synthesized NPs as anticancer treatment against human breast, colon and lung cancers and carcinoma.

Colorimetric sensor based on biogenic nanomaterials for high sensitive detection of hydrogen peroxide and multi-metals

Hydrogen peroxide (H2O2) and heavy metals, which are among the wastes of the industrial sector, become a threat to living things and the environment above certain concentrations. Therefore, the detection of both H2O2 and heavy metals with simple, low-cost, and fast analytical methods has gained great importance. The use of nanoparticles in colorimetric sensor technology for the detection of these analytes provides great advantages. In recent years, green synthesis of nanomaterials with products that can be considered biowaste is among the popular topics. In this study, silver/silver chloride nanoparticles (Ag@AgCl NPs) were synthesized using the green synthesis method as an eco-friendly and cheap method, the green algae extract was used as a reducing agent. The characterization of Ag@AgCl nanoparticles and green algae extract was carried out with several techniques such as Transmission Electron Microscopy (TEM), UV-Visible spectrometry (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction patterns (XRD) methods were used for characterization. According to TEM analysis, the Ag@AgCl NPs typically spherical in form and range in size from 4 to 10 nm, and UV-vis showed the formation of surface plasmon resonance (SPR) of the Ag@AgCl between 400 and 450 nm. In addition, its activity as a colorimetric sensor for hydrogen peroxide (H2O2) and multi-metal detection was evaluated. Interestingly, Ag/AgCl NPs caused different color formations for 3 metals simultaneously in the sensor study for heavy metal detection, and Fe3+, Cu2+, and Cr6+ ions were detected. The R2 values for H2O2, Fe3+, Cu2+, and Cr6+ were 0.9360, 0.9961, 0.9787, and 0.9625 the limit of detection (LOD) was 43.75, 1.69, 3.18, and 5.05 ppb (ng/mL), respectively. It was determined that Ag@AgCl NPs have the potential to be used as a colorimetric sensor for the detection of H2O2 and heavy metals from wastewater.

Enhancing the Reliability of SERS Detection in Ampicillin Using Oriented Tetrahedral Framework Nucleic Acid Probes and a Long-Range SERS Substrate

Indirect surface-enhanced Raman scattering (SERS)-based methods are highly efficient in detecting and quantitatively analyzing trace antibiotics in complex samples. However, the poor reproducibility of indirect SERS assays caused by the diffusion and orientation changes of the probing molecules on SERS substrates still presents a significant challenge. To address this issue, this study reports the construction of a novel SERS sensing platform using tetrahedral framework nucleic acid (tFNA) as SERS probes in conjunction with a long-range SERS (LR-SERS) substrate. The tFNA was modified with sulfhydryl groups at three vertices and appended with a probing DNA at the remaining vertex, anchored on the substrate surface with a well-ordered orientation and stable coverage density, resulting in highly reproducible SERS signals. Owing to the weak SERS signal of tFNA inherited from its size being larger than the effective range of the enhancing electric field (E-field) of conventional SERS substrates, we utilized an LR-SERS substrate to enhance the signal of tFNA probes by capitalizing on its extended E-field. Correspondingly, the LR-SERS substrate demonstrated a 54-fold increase in the intensity of tFNA probes compared to the conventional substrate. Using this novel platform, we achieved a highly reliable detection of the antibiotic ampicillin with a wide linear range (10 fM to 1 nM), low detection limit (3.1 fM), small relative standard deviation (3.12%), and yielded quantitative recoveries of 97-102% for ampicillin in water, milk, and human serum samples. These findings, therefore, effectively demonstrate the achievement of highly reliable SERS detection of antibiotics using framework nucleic acids and an LR-SERS substrate.

One-Pot Biosynthesis of Carbon-Coated Silver Nanoparticles Using Palm Leaves as a Reductant and a Carbon Source

In this study, carbon-coated silver nanoparticles (Ag@C NPs) were synthesized with a one-pot hydrothermal method using palm leaves as a reductant and a carbon source. SEM, TEM, XRD, Raman, and UV-vis analyses were employed to characterize the as-prepared Ag@C NPs. Results showed that the diameter of silver nanoparticles (Ag NPs) and the coating thickness could be controlled by changing the amount of biomass and the reaction temperature. The diameter ranged from 68.33 to 143.15 nm, while the coating thickness ranged from 1.74 to 4.70 nm. As the biomass amount and the reaction temperature increased, the diameter of Ag NPs and the coating thickness became larger. Thus, this work provided a green, simple, and feasible method for the preparation of metal nanocrystals.

Delivery of Apoplastic Extracellular Vesicles Encapsulating Green-Synthesized Silver Nanoparticles to Treat Citrus Canker

The citrus canker pathogen Xanthomonas axonopodis has caused severe damage to citrus crops worldwide, resulting in significant economic losses for the citrus industry. To address this, a green synthesis method was used to develop silver nanoparticles with the leaf extract of Phyllanthus niruri (GS-AgNP-LEPN). This method replaces the need for toxic reagents, as the LEPN acts as a reducing and capping agent. To further enhance their effectiveness, the GS-AgNP-LEPN were encapsulated in extracellular vesicles (EVs), nanovesicles with a diameter of approximately 30-1000 nm naturally released from different sources, including plant and mammalian cells, and found in the apoplastic fluid (APF) of leaves. When compared to a regular antibiotic (ampicillin), the delivery of APF-EV-GS-AgNP-LEPN and GS-AgNP-LEPN to X. axonopodis pv. was shown to have more significant antimicrobial activity. Our analysis showed the presence of phyllanthin and nirurinetin in the LEPN and found evidence that both could be responsible for antimicrobial activity against X. axonopodis pv. Ferredoxin-NADP⁺ reductase (FAD-FNR) and the effector protein XopAI play a crucial role in the survival and virulence of X. axonopodis pv. Our molecular docking studies showed that nirurinetin could bind to FAD-FNR and XopAI with high binding energies (-10.32 kcal/mol and -6.13 kcal/mol, respectively) as compared to phyllanthin (-6.42 kcal/mol and -2.93 kcal/mol, respectively), which was also supported by the western blot experiment. We conclude that (a) the hybrid of APF-EV and GS-NP could be an effective treatment for citrus canker, and (b) it works via the nirurinetin-dependent inhibition of FAD-FNR and XopAI in X. axonopodis pv.

Shoot-root signal circuit: Phytoremediation of heavy metal contaminated soil

High concentrations of heavy metals in the environment will cause serious harm to ecosystems and human health. It is urgent to develop effective methods to control soil heavy metal pollution. Phytoremediation has advantages and potential for soil heavy metal pollution control. However, the current hyperaccumulators have the disadvantages of poor environmental adaptability, single enrichment species and small biomass. Based on the concept of modularity, synthetic biology makes it possible to design a wide range of organisms. In this paper, a comprehensive strategy of "microbial biosensor detection - phytoremediation - heavy metal recovery" for soil heavy metal pollution control was proposed, and the required steps were modified by using synthetic biology methods. This paper summarizes the new experimental methods that promote the discovery of synthetic biological elements and the construction of circuits, and combs the methods of producing transgenic plants to facilitate the transformation of constructed synthetic biological vectors. Finally, the problems that should be paid more attention to in the remediation of soil heavy metal pollution based on synthetic biology were discussed.

Green Synthesis of Near-Infrared Plasmonic Gold Nanostructures by Pomegranate Extract and Their Supramolecular Assembling with Chemo- and Photo-Therapeutics

Au nanostructures exhibiting a localized surface plasmon resonance in the near-infrared spectral window are obtained in a single, green step at room temperature by pomegranate extract in the presence of a highly biocompatible β-cyclodextrin branched polymer, without the need of preformed seeds, external reducing and sacrificial agents, and conventional surfactants. The polymeric component makes the Au nanostructures dispersible in water, stable for weeks and permits their supramolecular assembling with the chemotherapeutic sorafenib and a nitric oxide (NO) photodonor (NOPD), chosen as representative for chemo- and photo-therapeutics. Irradiation of the plasmonic Au nanostructures in the therapeutic window with 808 nm laser light results in a good photothermal response, which (i) is not affected by the presence of either the chemo- or the phototherapeutic guests and (ii) does not lead to their photoinduced decomposition. Besides, irradiation of the hybrid Au nanoassembly with the highly biocompatible green light results in the NO release from the NOPD with efficiency similar to that observed for the free guest. Preliminary biological experiments against Hep-G2 hepatocarcinoma cell lines are also reported.

Biomimetic Nanomaterials: Diversity, Technology, and Biomedical Applications

Biomimetic nanomaterials (BNMs) are functional materials containing nanoscale components and having structural and technological similarities to natural (biogenic) prototypes. Despite the fact that biomimetic approaches in materials technology have been used since the second half of the 20th century, BNMs are still at the forefront of materials science. This review considered a general classification of such nanomaterials according to the characteristic features of natural analogues that are reproduced in the preparation of BNMs, including biomimetic structure, biomimetic synthesis, and the inclusion of biogenic components. BNMs containing magnetic, metal, or metal oxide organic and ceramic structural elements (including their various combinations) were considered separately. The BNMs under consideration were analyzed according to the declared areas of application, which included tooth and bone reconstruction, magnetic and infrared hyperthermia, chemo- and immunotherapy, the development of new drugs for targeted therapy, antibacterial and anti-inflammatory therapy, and bioimaging. In conclusion, the authors' point of view is given about the prospects for the development of this scientific area associated with the use of native, genetically modified, or completely artificial phospholipid membranes, which allow combining the physicochemical and biological properties of biogenic prototypes with high biocompatibility, economic availability, and scalability of fully synthetic nanomaterials.

Utility of Biogenic Iron and Its Bimetallic Nanocomposites for Biomedical Applications: A Review

Nanotechnology mainly deals with the production and application of compounds with dimensions in nanoscale. Given their dimensions, these materials have considerable surface/volume ratios, and hence, specific characteristics. Nowadays, environmentally friendly procedures are being proposed for fabrication of Fe nanoparticles because a large amount of poisonous chemicals and unfavorable conditions are needed to prepare them. This work includes an inclusive overview on the economical and green procedures for the preparation of such nanoparticles (flower, fruits, tea, carbohydrates, and leaves). Pure and bimetallic iron nanoparticles, for instance, offer a high bandwidth and excitation binding energy and are applicable in different areas ranging from antibacterial, anticancer, and bioimaging agents to drug delivery systems. Preparation of nano-sized particles, such as those of Fe, requires the application of high quantities of toxic materials and harsh conditions, and naturally, there is a tendency to develop more facile and even green pathways (Sultana, Journal of Materials Science & Technology, 2013, 29, 795–800; Bushra et al., Journal of hazardous materials, 2014, 264, 481–489; Khan et al., Ind. Eng. Chem. Res., 2015, 54, 76–82). This article tends to provide an overview on the reports describing green and biological methods for the synthesis of Fe nanoparticles. The present review mainly highlights selenium nanoparticles in the biomedical domain. Specifically, this review will present detailed information on drug delivery, bioimaging, antibacterial, and anticancer activity. It will also focus on procedures for their green synthesis methods and properties that make them potential candidates for various biomedical applications. Finally, we provide a detailed future outlook.

In Vitro and In Vivo Anticancer and Genotoxicity Profiles of Green Synthesized and Chemically Synthesized Silver Nanoparticles

Silver nanoparticles were green synthesized (Ag-PTs) employing the crude extract of Padina tetrastromatica, a marine alga, and their anticancer and safety profile were compared with those of chemically synthesized silver nanoparticles (Ag-NPs) by in vitro and in vivo models. Ag-PT exhibited potent cytotoxicity against B16-F10 (IC₅₀ = 3.29), MCF-7 (IC₅₀ = 4.36), HEPG2 (IC₅₀ =3.89), and HeLa (IC₅₀ = 4.97) cancer cell lines, whereas they exhibited lower toxicity on normal CHO-K1 cells (IC₅₀ = 5.16). The potent anticancer activity of Ag-PTs on cancer cells is due to the liberation of ions from the nanoparticles. Increased ion internalization to the cells promotes reactive oxygen species (ROS) production and ultimately leads to cell death. The in vitro anticancer results and in vivo melanoma tumor regression study showed significant inhibition of melanoma tumor growth due to Ag-PT treatment. Ag-PT is involved in the upregulation of the p53 protein and downregulation of Sox-2 along with the Ki-67 protein. The antitumor effects of Ag-PTs may be due to the additional release of ions at a lower pH of the tumor microenvironment than that of the normal tissue. The results of safety investigations of Ag-PT by studying mitotic chromosome aberrations (CAs), micronucleus (MN) induction, and mitotic index (MI) demonstrated Ag-PT to be less genotoxic compared to Ag-NP. The bioefficacy and toxicology outcomes together demonstrated that the green synthesized silver nanoparticles (Ag-PTs) could be explored to develop a biocompatible, therapeutic agent and a vehicle of drug delivery for various biomedical applications.

Prospects of algae-based green synthesis of nanoparticles for environmental applications

Green synthesis of nanoparticles (NPs) has emerged as an eco-friendly alternative to produce nanomaterials with diverse physical, chemical, and biological characteristics. Previously used, physical and chemical methods involve the production of toxic byproducts, costly instrumentation, and energy-intensive experimental processes thereby, limiting their applicability. Biogenic synthesis of nanoparticles has come forward as a potential alternative, providing an eco-friendly, cost-effective, and energy-efficient approach for the synthesis of a diverse range of NPs. Several biological entities are employed in the biosynthesis of NPs including bacteria, fungi, and algae. However, the distinguishing characteristics of microalgae and cyanobacteria make them promising candidates for NPs synthesis because of their higher growth rate, substantially higher rate of sequestering CO₂, hyperaccumulation of heavy metals, absence of toxic byproducts, minimum energy input, and employment of biomolecules (pigments and enzymes) as reducing and capping agents. Algal extract, being a natural reducing and capping agent, serves as a living cell factory for the efficient green synthesis of nanoparticles. Physiological and biological methods allow algal cells to uptake heavy metals and utilize them as nutrient source to generate biomass by regulating their metabolic processes. Despite their enormous potential, studies on the microalgae-based synthesis of nanoparticles for the removal of toxic pollutants from wastewater remained an unexplored research area in the literature. This review was aimed to summarize the recent advancements and prospects in the algae-based synthesis of nanoparticles for environmental applications particularly treating the wastewater.

Anticancer and antimicrobial activity of biosynthesized Red Sea marine algal silver nanoparticles

Biosynthesis of silver nanoparticles (AgNPs) is emerging as a simple and eco-friendly alternative to conventional chemical synthesis methods. The role of AgNPs is expanding as antimicrobial and anticancer agents, sensors, nanoelectronic devices, and imaging contrast agents. In this study, biogenic AgNPs were synthesized using extracts of different marine algae species, including Ulva rigida (green alga), Cystoseira myrica (brown alga), and Gracilaria foliifera (red alga), as reducing and capping agents. The Physiochemical properties, cytotoxicity, anticancer and antimicrobial activities of the biosynthesized AgNPs were assessed. Surface plasmonic bands of the biosynthesized AgNPs capped with U. rigida, C. myrica, and G. foliifera extracts were visually observed to determine a colour change, and their peaks were observed at 424 nm, 409 nm, and 415 nm, respectively, by UV-Vis spectroscopy; transmission electron microscopy (TEM) indicated an almost spherical shape of AgNPs with nanoscale sizes of 12 nm, 17 nm, and 24 nm, respectively. Fourier transform-infrared (FTIR) spectroscopy analysis suggested that different molecules attached to AgNPs through OH, C=O, and amide groups. The major constituents of the aqueous algal extracts included, terpenoids, polyphenols, sulfonates, polysaccharides, fatty acids, chlorophylls, amide proteins, flavonoids, carotenoids, aliphatic fluoro compounds, volatile compounds, alkalines, pyruvic acid and agar groups. The cytotoxicity and anticancer activities of the biosynthesized AgNPs were assessed using Artemia salina nauplii, normal skin cell lines (HFb-4), and breast cancer cell lines (MCF-7 cell line). The lethality was found to be directly proportional to the AgNP concentration. The IC50 values of C. myrica and G. foliifera AgNPs against A. saline nauplii were 5 and 10 μg ml-1 after 4 h and 16 h, respectively, whereas U. rigida AgNPs did not exhibit cytotoxic effects. Anticancer activity of the biosynthesized AgNPs was dose dependent. The IC50 values of the biosynthesized AgNPs were 13, 13, and 43 µg ml-1 for U. rigida, C. myrica, and G. foliifera, respectively. U. rigida AgNPs particularly exhibited potent anticancer activity (92.62%) against a human breast adenocarcinoma cell line (MCF-7) with high selectivity compared the normal cells (IC50 = 13 µg/ml, SI = 3.2), followed by C. myrica AgNPs (IC50 = 13 µg/ml, SI = 3.07). Furthermore, the biosynthesized AgNPs exhibited strong antifungal activity against dermatophyte pathogenic moulds and mild antibacterial activity against the food borne pathogen bacteria. The highest antimicrobial activity was recorded for the U. rigida AgNPs, followed by those capped with C. myrica and G. foliifera extracts, respectively. AgNPs capped with the U. rigida extract exhibited the highest antimicrobial activity against Trichophyton mantigrophytes (40 mm), followed by Trichosporon cataneum (30 mm) and E. coli (19 mm), with minimal lethal concentration of 32 and 64 μg ml-1 respectively. The study finally revealed that extracts of marine algal species, particularly U. rigida extracts, could be effectively used as reducing agents for the green synthesis of AgNPs. These AgNPs are considered efficient alternative antidermatophytes for skin infections and anticancer agents against the MCF-7 cell line.

Role of Biogenic Capping Agents in the Synthesis of Metallic Nanoparticles and Evaluation of Their Therapeutic Potential

The biomedical properties of nanoparticles have been the area of focus for contemporary science; however, there are issues concerning their long-term toxicities. Recent trends in nanoparticle fabrication and surface manipulation, the use of distinctive biogenic capping agents, have allowed the preparation of nontoxic, surface-functionalized, and monodispersed nanoparticles for medical applications. These capping agents act as stabilizers or binding molecules that prevent agglomeration and steric hindrance, alter the biological activity and surface chemistry, and stabilize the interaction of nanoparticles within the preparation medium. Explicit features of nanoparticles are majorly ascribed to the capping present on their surface. The present review article is an attempt to compile distinctive biological capping agents deployed in the synthesis of metal nanoparticles along with the medical applications of these capped nanoparticles. First, this innovative review highlights the various biogenic capping agents, including biomolecules and biological extracts of plants and microorganisms. Next, the therapeutic applications of capped nanoparticles and the effect of biomolecules on the efficiency of the nanoparticles have been expounded. Finally, challenges and future directions on the use of biological capping agents have been concluded. The goal of the present review article is to provide a comprehensive report to researchers who are looking for alternative biological capping agents for the green synthesis of important metallic nanoparticles.

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications

Bio-nanotechnology has emerged as an efficient and competitive methodology for the production of added-value nanomaterials (NMs). This review article gathers knowledge gleaned from the literature regarding the biosynthesis of sulfur-based chalcogenide nanoparticles (S-NPs), such as CdS, ZnS and PbS NPs, using various biological resources, namely bacteria, fungi including yeast, algae, plant extracts, single biomolecules, and viruses. In addition, this work sheds light onto the hypothetical mechanistic aspects, and discusses the impact of varying the experimental parameters, such as the employed bio-entity, time, pH, and biomass concentration, on the obtained S-NPs and, consequently, on their properties. Furthermore, various bio-applications of these NMs are described. Finally, key elements regarding the whole process are summed up and some hints are provided to overcome encountered bottlenecks towards the improved and scalable production of biogenic S-NPs.

Biogenic metal nanoparticles with microbes and their applications in water treatment: a review

Due to their unique characteristics, nanomaterials are widely used in many applications including water treatment. They are usually synthesized via physiochemical methods mostly involving toxic chemicals and extreme conditions. Recently, the biogenic metal nanoparticles (Bio-Me-NPs) with microbes have triggered extensive exploration. Besides their environmental-friendly raw materials and ambient biosynthesis conditions, Bio-Me-NPs also exhibit the unique surface properties and crystalline structures, which could eliminate various contaminants from water. Recent findings in the synthesis, morphology, composition, and structure of Bio-Me-NPs have been reviewed here, with an emphasis on the metal elements of Fe, Mn, Pd, Au, and Ag and their composites which are synthesized by bacteria, fungi, and algae. Furthermore, the mechanisms of eliminating organic and inorganic contaminants with Bio-Me-NPs are elucidated in detail, including adsorption, oxidation, reduction, and catalysis. The scale-up applicability of Bio-Me-NPs is also discussed.

Nanogold-based materials in medicine: from their origins to their future

The properties of gold-based materials have been explored for centuries in several research fields, including medicine. Multiple published production methods for gold nanoparticles (AuNPs) have shown that the physicochemical and optical properties of AuNPs depend on the production method used. These different AuNP properties have allowed exploration of their usefulness in countless distinct biomedical applications over the last few years. Here we present an extensive overview of the most commonly used AuNP production methods, the resulting distinct properties of the AuNPs and the potential application of these AuNPs in diagnostic and therapeutic approaches in biomedicine.

Biological Synthesis of Nanocatalysts and Their Applications

Over the past few decades, the synthesis and potential applications of nanocatalysts have received great attention from the scientific community. Many well-established methods are extensively utilized for the synthesis of nanocatalysts. However, most conventional physical and chemical methods have some drawbacks, such as the toxicity of precursor materials, the requirement of high-temperature environments, and the high cost of synthesis, which ultimately hinder their fruitful applications in various fields. Bioinspired synthesis is eco-friendly, cost-effective, and requires a low energy/temperature ambient. Various microorganisms such as bacteria, fungi, and algae are used as nano-factories and can provide a novel method for the synthesis of different types of nanocatalysts. The synthesized nanocatalysts can be further utilized in various applications such as the removal of heavy metals, treatment of industrial effluents, fabrication of materials with unique properties, biomedical, and biosensors. This review focuses on the biogenic synthesis of nanocatalysts from various green sources that have been adopted in the past two decades, and their potential applications in different areas. This review is expected to provide a valuable guideline for the biogenic synthesis of nanocatalysts and their concomitant applications in various fields.

Algae-mediated biosystems for metallic nanoparticle production: From synthetic mechanisms to aquatic environmental applications

Driven by the growing impetus of green chemistry and environmental protection, the use of bio-based systems to produce green metallic nanomaterials used for environmental remediation has thus developed urgently. It is proposed that using algae as a living cell factory or algal extract as a natural reducing agent is a green and clean way to efficiently synthesize various metallic nanomaterials. However, studies on algal-based biological synthesis of metallic nanomaterials and their applications towards removal of toxic pollutants from wastewater are still limited, which largely discourage the sustainability. Herein, this review aims to introduce the recent advances on algae-mediated nanomaterial-producing biosystems. The corresponding synthetic mechanisms, operation parameters, and case studies on various algae-synthesized metallic nanoparticles are comprehensively discussed and summarized. More importantly, the applicability of algae-synthesized metallic nanoparticles on water treatment is introduced in-depth. To improve economic viability, the challenges and future perspectives are also considered. Taken together, this review systematically presents the achievements and current progress of algae-mediated metallic nanoparticle biosynthesis towards the aquatic pollutants treatment, which can provide new insights on promoting the algae-based nanomaterial production yield and environmental application potential.

Cyanobacteria as biochemical energy source for the synthesis of inorganic nanoparticles, mechanism and potential applications: a review

Green synthesis of nanoparticles (NPs) has gained great concern among researchers due to their unique properties, excellent applications and efficient route of synthesis. From the last decades, the number biologicals such as plants, fungus, bacteria, yeast, algae, and cyanobacteria and their products are using by various researchers for the synthesis of different NPs. However, the pillar of green chemistry keeps touching new heights to improve the performance. This review paper unveils almost recent cyanobacteria-assisted greener NP synthesis technique, characterization and application. The enormous potency of cyanobacteria in NP synthesis (silver, gold, copper, zinc, palladium, titanium, cadmium sulfide, and selenium) and significance of reducing enzymes were summarized. The extracellular and intracellular entity such as metabolites, enzyme, protein, pigments in cyanobacteria play a significant role in the conversion of metal ions to metal NPs with unique properties discussed briefly. The green synthesis of nanomaterials is valuable because of their cost-effective, nontoxic and eco-friendly prospects as well as the potential application metal NPs such as antibacterial, antifungal, anticancerous, catalytic, drug delivery, bioimaging, nanopesticide, nanofertilizer, sensing properties, etc. Therefore, in the present review, we have systematically discussed the mechanisms of synthesis and applications of cyanobacteria-assisted green synthesis of NPs.

Synthesis of near-infrared absorbing triangular Au nanoplates using biomineralisation peptides

Triangular Au nanoplates (TrAuNPls) possessing strong plasmonic properties can be used as photothermal agents in cancer therapy. However, the controlled preparation of such morphologies typically requires harsh synthetic conditions. Biomolecules offer an alternative route to developing biocompatible synthetic protocols. In particular, peptides offer a novel route for inorganic synthesis under ambient conditions. Herein, using the previously isolated peptide, ASHQWAWKWE, for Au nanoparticle (AuNP) synthesis, the conditions for preparing TrAuNPls via a one-pot synthetic process of mixing HAuCl₄ and peptides at room temperature were investigated to effectively obtain particles possessing near-infrared absorbance for non-invasive optical diagnosis and phototherapy. By adjusting the peptide concentration, the size and property of TrAuNPls were controlled under neutral pH conditions. The synthesised particles showed potential as photothermal therapeutic agents in vitro. In addition, peptide characterisation using B3 derivatives revealed the importance of the third amino acid histidine in morphological regulation and potential circular Au nanoplates (AuNPl) synthesis with ASEQWAWKWE and ASAQWAWKWE peptides. These findings provide not only an easy and green synthetic method for TrAuNPls and circular AuNPls, but also some insight to help elucidate the regulation of peptide-based nanoparticle synthesis for use in cancer therapy. STATEMENT OF SIGNIFICANCE: Biological molecules have received increasing attention as a vehicle to synthesise inorganic materials with specific properties under ambient conditions; particularly, short peptides have the potential to control the synthesis of nanoscale materials with tailored functions. Here, the application of a previously isolated peptide was assessed in synthesising Au nanoparticles containing decahedral and triangular nanoplates with near-infrared absorbance. The size and absorbance peaks of the triangular nanoplates observed were peptide concentration-dependent. In addition, these fine-tuned triangular nanoplates exhibited potential as a phototherapeutic agent. Moreover, the peptide derivatives indicated the possibility of synthesising circular nanoplates. These findings may offer insight into development of new techniques for synthesising functional nanoparticles having biological applications using non-toxic molecules under mild conditions stituted in the original B3 peptide is underlined.

Recent Advancements in Green Synthesis of Nanoparticles for improvement of bioactivities: a Review

Natural products have widely been used in applications ranging from antibacterial, antiviral, antifungal and various other medicinal applications. Use of these natural products was recognized way before the establishment of basic chemistry behind the disease and the chemistry of plant metabolites. After the establishment of plant chemistry various new horizons evolved, and application of the natural products breached the orthodox limitations. In one such interdisciplinary area, use of plant materials in the synthesis of nano particles (NPs) has exponentially emerged. This advancement has offered various environment friendly methods where hazardous chemicals are completely replaced by natural products in the sophisticated and hectic synthesis processes. This review is an attempt to understand the mechanism of metal nano particles synthesis using plant materials. It includes details on the role of plant's secondary metabolites in the synthesis of nano particles including the mechanism of action. In addition, use of these nano materials has widely been discussed along with the possible mechanism behind their antimicrobial and catalytic action.

Exploration of Microbial Factories for Synthesis of Nanoparticles - A Sustainable Approach for Bioremediation of Environmental Contaminants

The nanomaterials synthesis is an intensifying research field due to their wide applications. The high surface-to-volume ratio of nanoparticles and quick interaction capacity with different particles make them as an attractive tool in different areas. Conventional physical and chemical procedures for development of metal nanoparticles become outmoded due to extensive production method, energy expenditure and generation of toxic by-products which causes significant risks to the human health and environment. Hence, there is a growing requirement to search substitute, non-expensive, reliable, biocompatible and environmental friendly methods for development of nanoparticles. The nanoparticles synthesis by microorganisms has gained significant interest due to their potential to synthesize nanoparticles in various sizes, shape and composition with different physico-chemical properties. Microbes can be widely applied for nanoparticles production due to easy handling and processing, requirement of low-cost medium such as agro-wastes, simple scaling up, economic viability with the ability of adsorbing and reducing metal ions into nanoparticles through metabolic processes. Biogenic synthesis of nanoparticles offers clean, non-toxic, environmentally benign and sustainable approach in which renewable materials can be used for metal reduction and nanoparticle stabilization. Nanomaterials synthesized through microbes can be used as a pollution abatement tool as they also contain multiple functional groups that can easily target pollutants for efficient bioremediation and promotes environmental cleanup. The objective of the present review is to highlight the significance of micro-organisms like bacteria, actinomycetes, filamentous fungi, yeast, algae and viruses for nanoparticles synthesis and advantages of microbial approaches for elimination of heavy metals, dyes and wastewater treatment.

Synthesis of intracellular and extracellular gold nanoparticles with a green machine and its antifungal activity

Green synthesis method is being increasingly used in the development of safe, stable, and eco-friendly nanostructures with biological resources. In this study, extracellular and intracellular synthesis of gold nanoparticles (AuNPs) was carried out using green algae Chlorella sorokiniana Shihira & R.W. Fresh algae were isolated and identified from Musaözü Pond located in the province of Eskişehir and then extraction process were performed. Optimization studies were studied using pH value, metal salt concentration, and time parameters for extracellular synthesis and using only time parameter for intrasellular synthesis. Since more controlled and optimum conditions can be achieved in the production of AuNPs by extracellular synthesis, these nanoparticles (NPs) were used for characterization and antifungal activity studies. Optical, physical, and chemical properties of synthesized NPs were characterized by UV visible spectrophotometer (UV-Vis), dynamic light scattering (DLS), Zetasizer, X-Ray diffraction (XRD), Fourier transform ınfrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), ınductively coupled plasma mass spectrometer (ICP-MS) and transmission electron microscope (TEM) analysis. The optimum conditions for AuNPs synthesis were determined as 1 mM for HauCl4 concentration, 6 for pH value, and 60th min for time. AuNPs obtained from extracellular synthesis from C. sorokiniana extract are 5-15 nm in size and spherical shape. TEM images of extracellular synthesis show noticeable cell wall and membrane damages, cytoplasma dissolutions, and irregularities. AuNPs obtained by intracellular synthesis are in 20-40 nm size and localized in the cell wall and cytoplasm. These NPs exhibited significant antifungal activity against C. tropicalis, C. glabrata, and C. albicans isolates. AuNPs obtained by algae-mediated green synthesis have a significant potential for medical and industrial use, and this eco-friendly synthesis method can be easily scaled for future studies.

Green Synthesis of Copper Oxide Nanoparticles Using Protein Fractions from an Aqueous Extract of Brown Algae Macrocystis pyrifera

Amongst different living organisms studied as potential candidates for the green synthesis of copper nanoparticles, algal biomass is presented as a novel and easy-to-handle method. However, the role of specific biomolecules and their contribution as reductant and capping agents has not yet been described. This contribution reports a green synthesis method to obtain copper oxide nanoparticles (CuO-NPs) using separated protein fractions from an aqueous extract of brown algae Macrocystis pyrifera through size exclusion chromatography (HPLC-SEC). Proteins were detected by a UV/VIS diode array, time-based fraction collection was carried out, and each collected fraction was used to evaluate the synthesis of CuO-NPs. The characterization of CuO-NPs was evaluated by Dynamic Light Scattering (DLS), Z-potential, Fourier Transform Infrared (FTIR), Transmission Electron Microscope (TEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) detector. Low Molecular Weight (LMW) and High Molecular Weight (HMW) protein fractions were able to synthesize spherical CuO-NPs. TEM images showed that the metallic core present in the observed samples ranged from 2 to 50 nm in diameter, with spherical nanostructures present in all containing protein samples. FTIR measurements showed functional groups from proteins having a pivotal role in the reduction and stabilization of the nanoparticles. The highly negative zeta potential average values from obtained nanoparticles suggest high stability, expanding the range of possible applications. This facile and novel protein-assisted method for the green synthesis of CuO-NPs may also provide a suitable tool to synthesize other nanoparticles that have different application areas.

An Overview of the Algae-Mediated Biosynthesis of Nanoparticles and Their Biomedical Applications

Algae have long been exploited commercially and industrially as food, feed, additives, cosmetics, pharmaceuticals, and fertilizer, but now the trend is shifting towards the algae-mediated green synthesis of nanoparticles (NPs). This trend is increasing day by day, as algae are a rich source of secondary metabolites, easy to cultivate, have fast growth, and are scalable. In recent era, green synthesis of NPs has gained widespread attention as a safe, simple, sustainable, cost-effective, and eco-friendly protocol. The secondary metabolites from algae reduce, cap, and stabilize the metal precursors to form metal, metal oxide, or bimetallic NPs. The NPs synthesis could either be intracellular or extracellular depending on the location of NPs synthesis and reducing agents. Among the diverse range of algae, the most widely investigated algae for the biosynthesis of NPs documented are brown, red, blue-green, micro and macro green algae. Due to the biocompatibility, safety and unique physico-chemical properties of NPs, the algal biosynthesized NPs have also been studied for their biomedical applications, which include anti-bacterial, anti-fungal, anti-cancerous, anti-fouling, bioremediation, and biosensing activities. In this review, the rationale behind the algal-mediated biosynthesis of metallic, metallic oxide, and bimetallic NPs from various algae have been reviewed. Furthermore, an insight into the mechanism of biosynthesis of NPs from algae and their biomedical applications has been reviewed critically.

Biogenic synthesis of silver nanoparticles using cyanobacterium Leptolyngbya sp. WUC 59 cell-free extract and their effects on bacterial growth and seed germination

The biogenic synthesis of metal nanoparticles (NPs) is of great significance, as it renders clean, biocompatible, innocuous and worthwhile production. Here, we present a clean and sustainable route for the synthesis of silver nanoparticles (Ag NPs) using the cell-free aqueous extract of the cyanobacterium Leptolyngbya sp. WUC 59, isolated from polluted water and identified using a polyphasic approach. The conformation and characterisation of the as-synthesized biogenic Ag NPs was carried out using various sophisticated techniques like UV-visible (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HRTEM). The sharp colour change and emergence of a characteristic peak at 430 nm in the UV-Vis spectrum confirm the formation of the Ag NPs. The morphological and physical appearance indicated that the synthesized Ag NPs are crystalline with a typical size of 20-35 nm. Furthermore, the bio-reduced nanoparticles were explored for their antibacterial activity against Bacillus subtilis and Escherichia coli bacteria, seed germination effects and early seedling growth of wheat (Triticum aestivum L.). The Ag NPs significantly suppressed the growth of both Bacillus subtilis and Escherichia coli bacteria with the treatment of 10 mg L-1 concentration within the initial 3 hours. The lower concentration (25 mg L-1) of the synthesized Ag NPs significantly enhanced the seed germination and early seedling growth of wheat in comparison to the control on the 4th and 8th day. The present investigations show that the use of the cyanobacterium Leptolyngbya sp. WUC 59 provides a simple, cost-effective and eco-friendly tool for the synthesis of Ag NPs. Moreover, it could have great potential for use as an alternative to chemical-based bactericides not only in pharmaceutical industries, but also to control bacterial diseases in agricultural crops.

π-π stacking-directed self-assembly of nanoplatelets into diversified three-dimensional superparticles for high surface-enhanced Raman scattering

Ordered, hierarchical structures formed from nanoparticle (NP) self-assembly are of interest as they display the synergistic properties of the individual NP. Herein we report a one-pot approach to form and self-assemble gold (Au) nanoplatelets into brick-wall like (BWL) Au superparticles (AuSPs). We employ an aniline (ANI) derivative, N-(3-amidino)-aniline (NAAN) to reduce the Au precursor into Au nanoplatelets in the presence of Br^-1. The corresponding oxidation product, poly (N-(3-amidino)-aniline) (PNAAN) functions as the capping agent and enables the face-to-face self-assembly of Au nanoplatelets into BWL AuSPs via the π-π stacking interaction. Systematically tuning the reaction conditions leads to spherical, mushroom- or cauliflower-like AuSPs. The significant electromagnetic enhancement of AuSPs via the formation of the nanogaps produces high-density hotspots for excellent surface-enhanced Raman scattering (SERS) enhancement, enabling the ultrasensitive SERS assay with detection limit of pM. Moreover, the as-prepared AuSPs exhibited the intense SERS signals under laser excitation with different wavelength and the excellent reproducibility after long-duration exposure in different media. The developed SERS sensor has a great potential for a wide application of bioanalysis, clinic assays and environmental monitoring.

Controlled synthesis of iron oxyhydroxide (FeOOH) nanoparticles using secretory compounds from Chlorella vulgaris microalgae

FeOOH nanoparticles are commonly synthesized at very high temperature and pressure that makes the process energy consuming and non-economic. Recently, novel approaches were developed for the fabrication of these particles at room temperature. But, the main problem with these methods is that the prepared structures are aggregates of ultra-small nanoparticles where no intact separate nanoparticles are formed. In this study, for the first time, secretory compounds from Chlorella vulgaris cells were employed for the controlled synthesis of FeOOH nanoparticles at room atmosphere. Obtained particles were found to be goethite (α-FeO(OH)) crystals. Controlled synthesis of FeOOH nanoparticles resulted in uniform spherical nanoparticles ranging from 8 to 17 nm in diameter with 12.8 nm mean particle size. Fourier-transform infrared and elemental analyses were indicated that controlled synthesized nanoparticles have not functionalized with secretory compounds of C. vulgaris, and these compounds just played a controlling role over the synthesis reaction.

Algae-based metallic nanoparticles: Synthesis, characterization and applications

Nanomaterials (NMs) tailored via conventional physicochemical routes play havoc with the environment that has led to the evolution of competent green routes for the actualization of a circular economy on an industrial-scale. Algae belonging to the class Cyanophyceae, Chlorophyceae, Phaeophyceae and Rhodophyceae have been harnessed as nano-machineries through intracellular and extracellular synthesis of gold (Au), silver (Ag) and several other metallic nanoparticles. Algae are an appealing platform for the production of diverse NMs, primarily due to the presence of bioactive compounds such as pigments and antioxidants in their cell extracts that act as biocompatible reductants. Chlorella spp. and Sargassum spp. have been extensively explored for the synthesis of nanoparticles having antimicrobial properties, which can potentially substitute conventional antibiotics. Characterization of nanoparticles (NPs) synthesised from algae has been done using advanced spectroscopic, diffractographic and microscopic techniques such as UV-Vis FT-IR, DLS, XPS, XRD, SEM, TEM, AFM, HR-TEM, and EDAX. The present paper reviews the information available on algae-mediated biosynthesis of various NPs, their characterization and applications in different domains.

Investigating the prospects of bacterial biosurfactants for metal nanoparticle synthesis - a comprehensive review

Establishing biological synthesis of nanoparticles is increasing nowadays in the field of nanotechnology. The search for an optimal source with durability, stability, capacity to withstand higher environmental conditions with excellent characteristics is yet to meet. Consequently, there is need to create an eco-friendly strategy for metal nanoparticle synthesis. One approach investigated in this review is the use of biosurfactants to enhance the synthesis biologically. In comparison with the other technologies, biosurfactants are less toxic and exhibit higher properties. This method is different from the conventional practice like physical and chemical methods. Several research studies represented that the biosurfactant influences the production of nanoparticles about 2-50 nm. In this manner, the research towards the biosurfactant has raised. This review also addressed the feasibility of biosurfactant and their benefits in the synthesis of metallic nanoparticles. The findings from this review can recommend a conceivable use of biosurfactant as a source for metal nanoparticle synthesis.

Photochemical Synthesis and Catalytic Applications of Gold Nanoplates Fabricated Using Quercetin Diphosphate Macromolecules

The demand for safer design and synthesis of gold nanoparticles (AuNPs) is on the increase with the ultimate goal of producing clean nanomaterials for biological applications. We hereby present a rapid, greener, and photochemical synthesis of gold nanoplates with sizes ranging from 10 to 200 nm using water-soluble quercetin diphosphate (QDP) macromolecules. The synthesis was achieved in water without the use of surfactants, reducing agents, or polymers. The edge length of the triangular nanoplates ranged from 50 to 1200 nm. Furthermore, the reduction of methylene blue was used to investigate the catalytic activity of AuNPs. The catalytic activity of triangular AuNPs was three times higher than that of the spherical AuNPs based on kinetic rate constants (k). The rate constants were 3.44 × 10^-2 and 1.11 × 10^-2 s^-1 for triangular and spherical AuNPs, respectively. The X-ray diffraction data of gold nanoplates synthesized by this method exhibited that the nanocrystals were mainly dominated by (111) facets which are in agreement to the nanoplates synthesized by using thermal and chemical approaches. The calculated relative diffraction peak intensity of (200), (220), and (311) in comparison with (111) was found to be 0.35, 0.17, and 0.15, respectively, which were lower than the corresponding standard values (JCPDS 04-0784). For example, (200)/(111) = 0.35 compared to 0.52 obtained from the standard (JCPDS 04-0784), indicating that the gold nanoplates are dominated by (111) facets. The calculated lattice from selected area electron diffraction data of the as-synthesized and after 1 year nanoplates was 4.060 and 4.088 Å, respectively. Our calculations were found to be in agreement with 4.078 Å for face-centered cubic gold (JCPDS 04-0784) and literature values of 4.07 Å. The computed QDP-Au complex demonstrated that the reduction process took place in the B ring of QDP. This approach contributes immensely to promoting the ideals of sustainable nanotechnology by eradicating the use of hazardous and toxic organic solvents.

Green Synthesis of Metal Nanoparticles and their Applications in Different Fields: A Review

Nanotechnology is an art for application and handling of materials at very small scales i.e. 1–100 nm. The materials at this scale exhibit significantly different properties compared to same materials at larger scales. There are so many physical and chemical methods for the synthesis of nanoscale materials but the most appropriate are the ones that synthesize materials using green chemistry eco-friendly techniques. Recently, the collaboration between nanotechnology and biology has opened up new horizons of nanobiotechnology that integrates the use of biological materials in a number of biochemical and biophysical processes. This approach has significantly boosted up nanoparticles (NPs) production without employing harsh and toxic conditions and chemicals. This review is aimed to provide an outline of latest developments in synthesis of NPs through biotic entities and their potential applications.

Green gold nanoparticles from plant-derived materials: an overview of the reaction synthesis types, conditions, and applications

Many studies have examined metallic nanoparticles (NPs) produced according to the principles of green chemistry. Gold NPs have drawn much more attention than other metallic NPs in recent years. Moreover, among all gold NP synthesis studies, using plant-derived molecules is one of the commonly used reductants in studies on NP synthesis because of its convenience in terms of shape, size control advantage, and nontoxic specifications. The present review focused on studies of the synthesis of gold NP types, including single gold atom NPs, alloyed AU NPs, and core-shell Au NPs as well as their conditions and applications. The effect of those structures on application fields such as catalysis, antifungal action, antibacterial activities, sensors and so on are also summarized. Furthermore, the morphology and synthesis conditions of the primer and secondary NP were discussed. In addition to synthesis methods, characterization methods were analyzed in the context of the considerable diversity of the reducing agents used. As the reducing agents used in most studies, polyphenols and proteins usually play an active role. Finally, the challenges and drawbacks in plant-derived agent usage for the preparation of Au NPs at various industries were also discussed.

Silver nanoparticles fabricated using medicinal plant extracts show enhanced antimicrobial and selective cytotoxic propensities

Nanoparticles fabricated using medicinal plant extract have great potential in the area of nanomedicine. High surface-to-volume ratio of nanoparticle enhances the local active biomolecules concentration, leading to many fold increase in the medicinal potentials. The silver nanoparticles (AgNPs) fabricated using indigenous medicinal plants of India, Azadirachta indica and Syzygium cumini, have shown a significant effect on the viability of prokaryotic and eukaryotic cells. Biofabrication of AgNP was confirmed using different spectroscopic and microscopic techniques. Extraction and purification of AgNP from non-conjugated plant moieties are done using centrifugation and size exclusion chromatography. The cytotoxic propensity of AgNP formulations was screened against Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria, cancerous (HT1080) and non-cancerous (HEK293) cell lines. The nanoparticle formulations showed a relatively higher cytotoxic propensity against Gram-positive bacteria and cancerous cell lines. In addition, the surface roughness and reactive oxygen species (ROS) measurements indicated that AgNP formulations mediate the cell activity predominantly by ROS-mediated disruptive change in membrane morphology upon direct interaction with the membrane. Hence, the nanoparticle formulations show an enhanced selective cytotoxic propensity towards Gram-positive bacteria and cancerous cell lines.