Effect of temperature on the size of biosynthesized silver nanoparticle: Deep insight into microscopic kinetics analysis

Green synthesis of copper oxide nanoparticles using extracts of Solanum macrocarpon fruit and their redox responses on SPAu electrode

In this work, CuO nanoparticles (NPs) were prepared from the aqueous extracts of Solanum macrocarpon fruit by using the conventional heating (CuO(h) NPs) and microwave irradiation (CuO(m) NPs) methods. The synthesized nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The SEM analysis revealed that the CuO NPs from both routes contained essentially smooth surfaces, and displayed some degree of agglomeration. The TEM analysis confirmed some spherical morphology with mean particle sizes of 35.60 ± 6.24 nm and 47.14 ± 6.18 nm for the CuO(h) and CuO(m) NPs respectively. While the CuO(m) NPs possessed a single-phase consistent with the face cantered cubic structure of copper oxide, the CuO(h) NPs showed some extra peaks attributed to Cu₂O NPs as secondary phase. Electrochemical studies were conducted in order to evaluate the electrochemical properties of the NPs. The responses of a gold screen-printed electrode surface treated with both NPs showed that their redox behaviours on (Fe(CN)₆)^3−/4− probe and KCl electrolytes vary significantly. In (Fe(CN)₆)^3−/4− probe, the SPAuE/CuO(h) showed enhanced electrochemical response relative to the bare, while the SPAuE/CuO(m) showed a lower current response than the bare. However, in the KCl electrolye, the SPAuE/CuO(h) and SPAuE/CuO(m) were highly electroactive and demonstrated peak current magnitude that was about 26.5 and 83.38 times higher than that of the bare. In this KCl medium, the magnitude of the oxidation peak current of Cu²⁺ for SPAuE/CuO(m) was about 3 times higher than that of SPAuE/CuO(h). The percentage contraction in redox coordinates between the 1^st and 10^th scans in both electrodes were 3.88 and 19.28% for SPAuE/CuO(h) and SPAuE/CuO(m) respectively. Thus, the choice of green synthesis route could be exploited in different fields where green NPs is desired.

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CuO NPs were prepared using aqueous extracts of Solanum macrocarpon fruit.

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Both the conventional heating and microwave irradiationmethods were employed.

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The microscopic and structural properties of the NPs were studied and compared.

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The electrochemical activities of the CuO modified SPAu electrodes were investigated.

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The synthesis routes played a major role in the growth and applicability of the NPs.

Intra-Organ Delivery of Nanotherapeutics for Organ Transplantation

Targeted delivery of therapeutics through the use of nanoparticles (NPs) has emerged as a promising method that increases their efficacy and reduces their side effects. NPs can be tailored to localize to selective tissues through conjugation to ligands that bind cell-specific receptors. Although the vast majority of nanodelivery platforms have focused on cancer therapy, efforts have begun to introduce nanotherapeutics to the fields of immunology as well as transplantation. In this review, we provide an overview from a clinician's perspective of current nanotherapeutic strategies to treat solid organ transplants with NPs during the time interval between organ harvest from the donor and placement into the recipient, an innovative technology that can provide major benefits to transplant patients. The use of ex vivo normothermic machine perfusion (NMP), which is associated with preserving the function of the organ following transplantation, also provides an ideal opportunity for a localized, sustained, and controlled delivery of nanotherapeutics to the organ during this critical time period. Here, we summarize previous endeavors to improve transplantation outcomes by treating the organ with NPs prior to placement in the recipient. Investigations in this burgeoning field of research are promising, but more extensive studies are needed to overcome the physiological challenges to achieving effective nanotherapeutic delivery to transplanted organs discussed in this review.

A Simple Colorimetric Analytical Assay for the Determination of Tetracyclines Based on In-situ Generation of Gold Nanoparticles Coupling with a Gold Staining Technique

The development of simple and sensitive detection methods for tetracyclines (TCs) is crucial for their routine detection. The present study developed a colorimetric method for the detection of TCs based on the in-situ generation of AuNPs, which were subsequently coupled with a gold staining reaction. Briefly, TCs containing phenolic groups reduce HAuCl₄ to form gold nanoparticles (AuNPs) as gold seeds. In the gold staining process, the gold seeds catalyze the reduction of HAuCl₄ by NH₂OH to form gold atoms that deposit on the surface of AuNPs, resulting in the enlargement of AuNPs. Sensitive detection of TCs was achieved by employing the gold staining technique. As low as 14, 18.9, and 1.98 nM of oxytetracycline (OTC), tetracycline (TC), and doxycycline (DC), respectively, could be sensitively detected. The proposed method also exhibited good repeatability and specificity, and then was applied to the determination of OTC in milk samples.

Synthesis of Sodium Alginate-Silver Nanocomposites Using Plasma Activated Water and Cold Atmospheric Plasma Treatment

In this study, sodium alginate (SA)-based, eco-friendly nanocomposites films were synthesized for potential food packaging applications using silver nitrate (AgNO₃) as the metal precursor, reactive nitrogen and oxygen species (RNOS) created within plasma activated water (PAW), or through cold plasma treatment (CP) as reducing agent and SA as stabilizing agent. The formation of silver nanoparticles (AgNPs) was confirmed via the absorption peaks observed between 440 and 450 nm in UV-vis spectroscopy. The tensile strength (TS) and tensile modulus (TM) of the nanocomposite films were significantly higher than those of the SA films. An increase in the TS was also observed as the AgNP concentration was increased from 1 to 5 mM. The storage modulus (G’) of the nanocomposite solution was higher than that of the SA solution. The synthesis of AgNPs resulted both in a higher solution viscosity and a more marked shear-thinning effect. The synthesized AgNPs showed antimicrobial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The AgNPs were spherical in shape with an average size of 22 nm.

GC-MS based lemon grass metabolite analysis involved in the synthesis of silver nanoparticles and evaluation of photo-catalytic degradation of methylene blue

Silver nanoparticles (AgNPs) is of great importance to scientific community due to their plethora of applications. Several plant extracts have been reported for synthesis of AgNPs. In this study, lemon grass was used as a reducing and capping agent to prepare AgNPs. The formation of AgNPs was confirmed by using UV-Vis spectra as AgNPs show a characteristic peak around 400 nm. Effect of pH, temperature and lemon grass extract to silver nitrate ratio was optimized using response surface methodology (RSM). Characterization of AgNPs was done using X-Ray Diffraction (XRD), Energy Dispersive X-Ray spectroscopy (EDX), Trasmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). Gas Chromatography-Mass spectrometry (GC-MS), Energy Dispersive X-Ray spectroscopy and Fourier Transform-Infrared (FT-IR) spectroscopic analysis showed involvement of metabolites of lemon grass in the formation of AgNPs. Photo-catalytic activity of synthesized AgNPs was evaluated through degradation of organic pollutant methylene blue dye.

Biosynthesis of Silver Nanoparticles Mediated by Entomopathogenic Fungi: Antimicrobial Resistance, Nanopesticides, and Toxicity

Silver nanoparticles are widely used in the biomedical and agri-food fields due to their versatility. The use of biological methods for the synthesis of silver nanoparticles has increased considerably due to their feasibility and high biocompatibility. In general, microorganisms have been widely explored for the production of silver nanoparticles for several applications. The objective of this work was to evaluate the use of entomopathogenic fungi for the biological synthesis of silver nanoparticles, in comparison to the use of other filamentous fungi, and the possibility of using these nanoparticles as antimicrobial agents and for the control of insect pests. In addition, the in vitro methods commonly used to assess the toxicity of these materials are discussed. Several species of filamentous fungi are known to have the ability to form silver nanoparticles, but few studies have been conducted on the potential of entomopathogenic fungi to produce these materials. The investigation of the toxicity of silver nanoparticles is usually carried out in vitro through cytotoxicity/genotoxicity analyses, using well-established methodologies, such as MTT and comet assays, respectively. The use of silver nanoparticles obtained through entomopathogenic fungi against insects is mainly focused on mosquitoes that transmit diseases to humans, with satisfactory results regarding mortality estimates. Entomopathogenic fungi can be employed in the synthesis of silver nanoparticles for potential use in insect control, but there is a need to expand studies on toxicity so to enable their use also in insect control in agriculture.

Smartphone enabled miniaturized temperature controller platform to synthesize nio/cuo nanoparticles for electrochemical sensing and nanomicelles for ocular drug delivery applications

Undoubtedly, various kinds of nanomaterials are of great significance due to their enormous applications in diverse areas. The structure and productivity of nanomaterials are heavily dependent on the process used for their synthesis. The synthesizing process plays a vital role in shaping nanomaterials effectively for better productivity. The conventional method requires expensive and massive thermal instruments, a huge volume of reagents. This paper aims to develop an Automatic Miniaturized Temperature Controller (AMTC) device for the synthesis of nickel oxide (NiO), copper oxide (CuO) nanoparticles, and nanomicelles. The device features a low-cost, miniaturized, easy-to-operate with plug-and-play power source, precise temperature control, and geotagged real-time data logging facility for the producing nanoparticles. With a temperature accuracy of ± 2 °C, NiO and CuO nanoparticles, and nanomicelles are synthesized on AMTC device, and are subjected to different characterizations to analyze their morphological structure. The obtained mean size of NiO and CuO is 27.14 nm and 85.13 nm respectively. As a proof-of-principle, the synthesized NiO and CuO nanomaterials are validated for electrochemical sensing of dopamine, hydrazine, and uric acid. Furthermore, the study is conducted, wherein, Dexamethasone (Dex) loaded nanomicelles are developed using AMTC device and compared to the conventional thin-film hydration method. Subsequently, as a proof-of-application, the developed nanomicelles are evaluated for transcorneal penetration using exvivo goat cornea model. Ultimately, the proposed device can be utilized for performing a variety of controlled thermal reactions on a minuscule platform with an integrated and miniaturized approach for various applications.

Green Synthesis of Transition-Metal Nanoparticles and Their Oxides: A Review

In recent years, many researchers have begun to shift their focus onto the synthesis of nanomaterials as this field possesses an immense potential that may provide incredible technological advances in the near future. The downside of conventional synthesis techniques, such as co-precipitation, sol-gel and hydrothermal methods, is that they necessitate toxic chemicals, produce harmful by-products and require a considerable amount of energy; therefore, more sustainable fabrication routes are sought-after. Biological molecules have been previously utilized as precursors for nanoparticle synthesis, thus eliminating the negative factors involved in traditional methods. In addition, transition-metal nanoparticles possess a broad scope of applications due to their multiple oxidation states and large surface areas, thereby allowing for a higher reactivity when compared to their bulk counterpart and rendering them an interesting research topic. However, this field is still relatively unknown and unpredictable as the biosynthesis of these nanostructures from fungi, bacteria and plants yield undesired diameters and morphologies, rendering them redundant compared to their chemically synthesized counterparts. Therefore, this review aims to obtain a better understanding on the plant-mediated synthesis process of the major transition-metal and transition-metal oxide nanoparticles, and how process parameters—concentration, temperature, contact time, pH level, and calcination temperature affect their unique properties such as particle size, morphologies, and crystallinity.

Bio-inspired PtNPs/Graphene nanocomposite based electrocatalytic sensing of metabolites of dipyrone

Noble metal nanoparticles are known to electrocatalyze various redox reactions by improving the electron transfer kinetics. In the present study, we have introduced a facile bioinspired synthesis of PtNPs and their integration for the formation of PtNPs/graphene nanocomposite using Psidium guajava (guava) leaves extract. Graphene used in nanocomposite formulation was synthesized by exfoliation of graphite in water/acetone (25:75 v/v) mixture followed by mechanical shearing using ultrasonication and microwave irradiation. PtNPs/graphene nanocomposite was drop-cast onto a glassy carbon electrode (GCE, 3 mm dia). The electrocatalytic activity of PtNPs/graphene nanocomposite was tested in a three-electrode system for sensing of metabolic products of dipyrone (DIP) formed through 1 e^- and 2 e^- transfer reactions. The modified electrode exhibited almost 50% reduction in electrode resistance. The limit of detection was found to be 0.142 μM with sensitivities of 0.820 and 0.445 μA․μM^-1cm^-2 for DIP concentration below and above 100 μM, respectively, using square wave voltammetry. The signal of sensing of metabolites of DIP was almost invariant in the presence of glucose, dopamine, uric acid, and ciprofloxacin; however, the response current was decayed by 20% within the 10th cycle. The sensing of DIP spiked in treated sewage-water and running tap-water samples was ∼100% recoverable and comparable with HPLC.

Lichens-A Potential Source for Nanoparticles Fabrication: A Review on Nanoparticles Biosynthesis and Their Prospective Applications

Green synthesis of nanoparticles (NPs) is a safe, eco-friendly, and relatively inexpensive alternative to conventional routes of NPs production. These methods require natural resources such as cyanobacteria, algae, plants, fungi, lichens, and naturally extracted biomolecules such as pigments, vitamins, polysaccharides, proteins, and enzymes to reduce bulk materials (the target metal salts) into a nanoscale product. Synthesis of nanomaterials (NMs) using lichen extracts is a promising eco-friendly, simple, low-cost biological synthesis process. Lichens are groups of organisms including multiple types of fungi and algae that live in symbiosis. Until now, the fabrication of NPs using lichens has remained largely unexplored, although the role of lichens as natural factories for synthesizing NPs has been reported. Lichens have a potential reducible activity to fabricate different types of NMs, including metal and metal oxide NPs and bimetallic alloys and nanocomposites. These NPs exhibit promising catalytic and antidiabetic, antioxidant, and antimicrobial activities. To the best of our knowledge, this review provides, for the first time, an overview of the main published studies concerning the use of lichen for nanofabrication and the applications of these NMs in different sectors. Moreover, the possible mechanisms of biosynthesis are discussed, together with the various optimization factors influencing the biological synthesis and toxicity of NPs.

A review on the green and sustainable synthesis of silver nanoparticles and one-dimensional silver nanostructures

The significance of silver nanostructures has been growing considerably, thanks to their ubiquitous presence in numerous applications, including but not limited to renewable energy, electronics, biosensors, wastewater treatment, medicine, and clinical equipment. The properties of silver nanostructures, such as size, size distribution, and morphology, are strongly dependent on synthesis process conditions such as the process type, equipment type, reagent type, precursor concentration, temperature, process duration, and pH. Physical and chemical methods have been among the most common methods to synthesize silver nanostructures; however, they possess substantial disadvantages and short-comings, especially compared to green synthesis methods. On the contrary, the number of green synthesis techniques has been increasing during the last decade and they have emerged as alternative routes towards facile and effective synthesis of silver nanostructures with different morphologies. In this review, we have initially outlined the most common and popular chemical and physical methodologies and reviewed their advantages and disadvantages. Green synthesis methodologies are then discussed in detail and their advantages over chemical and physical methods have been noted. Recent studies are then reviewed in detail and the effects of essential reaction parameters, such as temperature, pH, precursor, and reagent concentration, on silver nanostructure size and morphology are discussed. Also, green synthesis techniques used for the synthesis of one-dimensional (1D) silver nanostructures have been reviewed, and the potential of alternative green reagents for their synthesis has been discussed. Furthermore, current challenges regarding the green synthesis of 1D silver nanostructures and future direction are outlined. To sum up, we aim to show the real potential of green nanotechnology towards the synthesis of silver nanostructures with various morphologies (especially 1D ones) and the possibility of altering current techniques towards more environmentally friendly, more energy-efficient, less hazardous, simpler, and cheaper procedures.

A novel green synthesis of silver nanoparticles by the residues of Chinese herbal medicine and their biological activities

Green synthesis of silver nanoparticles (AgNPs) by using the extracts of Chinese herbal medicines (CHMs) has attracted tremendous attention due to the potential synergistic effect between metal nanoparticles and capping agents. However, since CHMs are precious and expensive, finding other cheap and eco-friendly resources for biosynthesizing AgNPs with superior medicinal activites is necessary. Herbal medicine residues (HMRs) are the by-products of traditional Chinese herbal medicine after decoction and were identified to contain approximately 30-50% of medicinally active ingredients, which may be advantageous for green synthesis of medicinal AgNPs. Inspired by this, we present herein the preparation of AgNPs by reusing Bazheng Mixture residues and evaluate both biosynthesis parameters and bioactivities, where Bazheng Mixture is a famous Chinese patent medicine for relieving inflammation and pain, and allaying fever. The UV-visible spectrum and DLS analysis showed that the as-prepared AgNPs were sensitive to pH, material proportion and incubation time, but the yield was impervious to material proportion. TEM, HRTEM, SAED and DLS characterization found that AgNPs (pH 10.0; material proportion 1 : 1; 6 h) had a face-centered cubic (fcc) structure and spherical shape with an average size of 22.2 ± 0.5 nm covered by anions, and existed in monodispersed form with long term stability. The AgNPs displayed potent toxic effects against both cancer cell lines and pathogens, and superior antioxidant activity. The IC50 for HCT116, HepG2 and HeLa cell lines were 13.07, 19.67, and 26.18 μg mL-1, respectively. The MICs of AgNPs for E. coli and S. aureus were both 50.0 μg mL-1. The uptake analysis of AgNPs for both pathogens and cancer cell lines was performed to preliminarily illustrate the mechanism of toxic effects. These results confirm that HMRs could be a low-cost, nontoxic and eco-friendly resource for green synthesis of medicinal AgNPs, and also provide an alternative method for general recycling strategies of HMRs.

Green Synthesis, Characterization and Antimicrobial Evaluation of Silver Nanoparticles for an Intracanal Dressing

Green chemistry has been applied in different areas due to the growing demands for renewable processes and one of them is nanotechnology. The aim of this study was to characterize a formulation containing silver nanoparticles (AgNPs) produced by a green synthesis and to evaluate its antimicrobial activity. The formulation will be used as an intracanal dressing exploiting the AgNPs' antimicrobial properties, which are crucial to prevent infections and bacterial reinfections that can compromise endodontic treatments. In the green synthesis, silver nitrate was employed as the precursor salt, maltose as a reducing agent, and gelatin as a stabilizing agent. The formulation was prepared mixing 50 % of a liquid containing the AgNPs and 50 % of hydroxyethylcellulose gel at 1.5 % with proper evaluation of the process inherent parameters. Techniques such as molecular absorption spectrometry and dynamic light scattering were used in characterization step. The antimicrobial activity of the AgNPs against Escherichia coli ATCC 25922, Enterococcus faecalis NCTC 775, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and Streptococcus mutans ATCC 25175 was verified according to National Comittee for Clinical Laboratory Standards (NCCLS) by determining minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The obtained results indicated the formulation containing AgNPs produced by a green synthesis was properly characterized by the selected techniques. Furthermore, the formulation assessment proved that it is suitable for the proposal as well as it has potential to be used as an intracanal dressing since presented antimicrobial activity against all bacterial strains evaluated.

Green Synthesis, Characterization, Antimicrobial, Anti-Cancer, and Optimization of Colorimetric Sensing of Hydrogen Peroxide of Algae Extract Capped Silver Nanoparticles

A green and cost-effective technique for the preparation of silver nanoparticles (Algae-AgNPs) as a colorimetric sensor for hydrogen peroxide (H2O2) is described. Silver nanoparticles were capped using the green algae (Noctiluca scintillans) extract at an optimum time of 3 h at 80 °C. The pH of the plant extract (pH = 7.0) yields nanoparticles with a mean size of 4.13 nm and a zeta potential of 0.200 ± 0.02 mV and negative polarity, using dynamic light scattering (DLS). High-resolution transmission electron microscopy (HRTEM) analysis showed regular spherical particles with the average size of 4.5 nm. Selected area electron diffraction (SAED) results revealed the polycrystalline nature of the silver nanoparticles. The obtained patterns were indexed as (111), (200), (220), and (311) reflections of the fcc (face centered cubic) silver crystal based on their d-spacing of 2.47, 2.13, 1.49, and 1.27 Å, respectively. The apparent color change from brown to colorless was observed when nanoparticles reacted with H2O2. Linear responses were obtained in three different ranges (nM, µM, and mM). Limits of detection (LOD) of 1.33 ± 0.02 and 1.77 ± 0.02 nM and quantitation limits (LOQ) of 7.31 ± 0.03 and 9.67 ± 0.03 nM were obtained for Abs and ΔAbs calibration curves, respectively. 10% v/v Algae-AgNPs solution inhibited Staphylococcus aureus over Escherichia coli, while a 50% reduction of tumor cell growth of MDA-MB-231 human breast adenocarcinoma was obtained.

Polyphenols profile of pomegranate leaves and their role in green synthesis of silver nanoparticles

The current study reports on polyphenols profile of pomegranate leaves (PL) Punica granatum grown in Egypt and exhibiting their role in development of an eco-friendly method of green synthesis of silver nanoparticles (AgNPs). PL aqueous alcohol extract was fractionated, the major phenolic compound was isolated from the polyphenols rich fraction (ethyl acetate fraction) and identified by conventional and spectroscopic methods of analysis as ellagic acid. Furthermore, the fraction was standardized and analysed using UPLC-PDA-UV and LC–MS-MS techniques revealing tentative identification of 23 polyphenolic compounds, quantifying ellagic acid as 43.14 ± 0.57 μg/mg of the fraction. AgNPs were successfully synthesized with the aid of polyphenols rich fraction. This is the first report revealing the systematic optimization of the green synthesis process using various independent variables. AgNPs were characterized by adopting UV–Vis spectroscopy, FTIR, XRD, and SEM, which revealed strong SPR band within average of λ _max 425 nm and polygonal shaped nanoparticles of 26.22 nm size, respectively. The antimicrobial efficacies of AgNPs and polyphenols rich fraction were tested against Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, and Sarcina lutea), Gram-negative bacteria (Salmonella paratyphi, Escherichia coli, and Pseudomonas aeruginosa) and fungi (Candida albicans). AgNPs showed a concentration-dependent activity against all the tested microorganisms.

Factors affecting the morphology of some organic and inorganic nanostructures for drug delivery: characterization, modifications, and toxicological perspectives

Introduction: In this review, we aim to highlight the impact of various processes and formulation variables influencing the characteristics of certain surfactant-based nanoconstructs for drug delivery. Areas covered: The review includes the discussion on processing parameters for the preparation of nanoconstructs, especially those made up of surfactants. Articles published in last 15 years (437) were reviewed, 381 articles were selected for data review and most appropriate articles (215) were included in article. Effect of variables such as surfactant concentration and type, membrane additives, temperature, and pH-dependent transitions on morphology has been highlighted along with effect of shape on nanoparticle uptake by cells. Various characterization techniques explored for these nanostructures with respect to size, morphology, lamellarity, distribution, etc., and a separate section on polymeric vesicles and the influence of block copolymers, type of block copolymer, control of block length, interaction of multiple block copolymers on the structure of polymersomes and chimeric nanostructures have been discussed. Finally, applications, modification, degradation, and toxicological aspects of these drug delivery systems have been highlighted. Expert opinion: Parameters influencing the morphology of micelles and vesicles can directly or indirectly affect the efficacy of small molecule cellular internalization as well as uptake in the case of biologicals.[Figure: see text].

Advances in biogenically synthesized shaped metal- and carbon-based nanoarchitectures and their medicinal applications

Non-spherical metal-based and carbon-based nanostructures have found applications in every facet of scientific endeavors, including engineering and biomedical fields. These nanostructures attract attention because of their biocompatibility and negligible cytotoxicity. Chemical and physical methods have been used for synthesizing earlier generations of metal-based and carbon-based nanostructures with variable architectures, including nanorods, nanowires, nanodots and nanosheets. However, these synthesis strategies utilize organic passivators which are toxic to the environment and the human body. Biogenic synthesis of nanoparticles is becoming increasing popular because of the necessity to develop eco-friendly and non-toxic strategies. Nanoparticles synthesized by natural compounds have immense potential in the biomedical arena. The present review focuses on plant-mediated synthesis of metal-based and carbon-based non-spherical nanoarchitectures and the role of green synthesis in improving their activities for biomedical applications.

Evaluation of biosynthesis parameters, stability and biological activities of silver nanoparticles synthesized by Cornus Officinalis extract under 365 nm UV radiation

Since silver nanoparticles (AgNPs) synthesized by using plant extracts revealed varied biological activities, the green synthesis of AgNPs has attracted considerable attention. Although the green synthesis of AgNPs have been accomplished by using the extracts of Cornus Officinalis, which is a traditional Chinese medicine and exhibits a wide spectrum of phytochemicals. The effects of biosynthesis parameters on reducing reaction, stability and more broad biological activities of so-prepared AgNPs did not been evaluated. In this paper, we firstly assessed the effects of UV radiation, pH, material proportion and radiation times on the green synthesis of AgNPs under 365 nm UV radiation by UV-visible spectrum and dynamic light scattering (DLS) analysis. The results showed that UV radiation could accelerate the formation of AgNPs and influence the average size below pH 7.0, and the size of so-prepared AgNPs were sensitive to the pH and material proportion, but no obvious changes to UV radiation times, offering a size-controlled synthetic method for AgNPs. The further X-ray diffraction (XRD), transmission electron microscopy (TEM) and DLS studies showed AgNPs synthesized at pH 7.0, extract: AgNO₃ = 1 : 1 and after 4 h UV radiation were a face-centered cubic (fcc) structure and both spherical and polygonal in shape with average particle size of 64.5 ± 0.3 nm existed in a monodispersed form. Subsquently, the stability of AgNPs was analyzed by zeta potential (-24.8 mV) and the average size measurement after 30 days storage (63.3 ± 0.4 nm), revealing a high degree of stability. Lastly, the investigation of biological activities showed that the biosynthesized AgNPs had potent antioxidant activity, antimicrobial activity against both S. aureus and E. coli as well as anticancer activity against HCT116 and HepG2 cell lines but negligible cytotoxicity against SW620. And the internalization of biosynthesized AgNPs inside the bacterial cell was evaluated by flow cytometric analysis, where the SSC values have significant increase after treating with nanoparticles. These results confirmed that the biosynthesis parameters on the green synthesis of AgNPs by using Cornus Officinalis extract also played pivotal roles and so-prepared AgNPs would be useful for the development of new alternative antioxidant, antimicrobial and anticancer agents in biomedicine.

Pyrimidine Derivative Schiff Base Ligand Stabilized Copper and Nickel Nanoparticles by Two Step Phase Transfer Method; in Vitro Anticancer, Antioxidant, Anti-Microbial and DNA Interactions

Pyrimidine derivative Schiff base ligand (DPMC) stabilized metal nanoparticles of copper (DPMC-CuNPs) and nickel (DPMC-NiNPs) were synthesized by modified Brust-Schiffrin technique, which is a two-step phase transfer assisted synthesis. The prepared metal nanoparticles were confirmed by UV-Visible and Infrared spectroscopy. The size, surface morphology and the quality of the DPMC and its MNPs were analyzed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) methods respectively. Electrochemical behavior of the DPMC-CuNPs and DPMC-NiNPs was analyzed by cyclic voltammetry method. DNA binding studies of the synthesized compounds with CT-DNA were examined by four different techniques such as UV-Visible and emission spectroscopy, cyclic voltametry and viscometric measurments. Thermal denaturation and sono-chemical denaturation studies of DNA with the DPMC, DPMC-CuNPs and DPMC-NiNPs results also suggest the synthesized compounds have good DNA binding ability. Various antioxidant scavenging studies results shows that DPMC and its copper and nickel nanoparticles have significant antioxidant activity. Antimicrobial studies of the DPMC and its MNPs were studied by Agar-Agar well diffusion method. Anticancer studies of the DPMC and its MNPs show that the DPMC-CuNPs and DPMC-NiNPs have significant anticancer activity with least toxicity than the standard drug cis-platin. Graphical Abstract.

Graphene Oxide-Silver Nanoparticle Nanohybrids: Synthesis, Characterization, and Antimicrobial Properties

Drug resistance of pathogenic microorganisms has become a global public health problem, which has prompted the development of new materials with antimicrobial properties. In this context, antimicrobial nanohybrids are an alternative due to their synergistic properties. In this study, we used an environmentally friendly one-step approach to synthesize graphene oxide (GO) decorated with silver nanoparticles (GO-AgNPs). By this process, spherical AgNPs of average size less than 4 nm homogeneously distributed on the surface of the partially reduced GO can be generated in the absence of any stabilizing agent, only with ascorbic acid (L-AA) as a reducing agent and AgNO3 as a metal precursor. The size of the AgNPs can be controlled by the AgNO3 concentration and temperature. Smaller AgNPs are obtained at lower concentrations of the silver precursor and lower temperatures. The antimicrobial properties of nanohybrids against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, Gram-positive Staphylococcus aureus, and the yeast Candida albicans were found to be concentration- and time-dependent. C. albicans and S. aureus showed the highest susceptibility to GO-AgNPs. These nanohybrids can be used as nanofillers in polymer nanocomposites to develop materials with antimicrobial activity for applications in different areas, and another potential application could be cancer therapeutic agents.

Inorganic nanoparticle synthesis in flow reactors – applications and future directions

The use of flow technologies for obtaining nanoparticles can play an important role in the development of ecological and sustainable processes for obtaining inorganic nanomaterials, and the continuous methods are part of the Flow Chemistry trend.

Bactericidal Properties of Plants-Derived Metal and Metal Oxide Nanoparticles (NPs)

Nanoparticles (NPs) are nano-sized particles (generally 1–100 nm) that can be synthesized through various methods. The wide range of physicochemical characteristics of NPs permit them to have diverse biological functions. These particles are versatile and can be adopted into various applications, particularly in biomedical field. In the past five years, NPs’ roles in biomedical applications have drawn considerable attentions, and novel NPs with improved functions and reduced toxicity are continuously increasing. Extensive studies have been carried out in evaluating antibacterial potentials of NPs. The promising antibacterial effects exhibited by NPs highlight the potential of developing them into future generation of antimicrobial agents. There are various methods to synthesize NPs, and each of the method has significant implication on the biological action of NPs. Among all synthetic methods, green technology is the least toxic biological route, which is particularly suitable for biomedical applications. This mini-review provides current update on the antibacterial effects of NPs synthesized by green technology using plants. Underlying challenges in developing NPs into future antibacterials in clinics are also discussed at the present review.