Nm For AuNPs Research Articles

Synthesis and Characterization of Gold Nanoparticles and Gold Nanoparticles Loaded with Bromelain

The production and use of nanometallic elements, such as gold, have received a lot of attention lately due to their distinctive features and wide range of uses. Most of these studies have employed the Turkevich approach. This research employed the Turkevich technique to produce gold nanoparticles (AuNPs). AuNPs and bromelain-loaded AuNPs were characterised using a variety of methods, including ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and zeta potential (ZP) measurements. The UV-Vis spectra of Bromelain, AuNPs, and AuNPs-Bromelain each had a peak at 276, 534, and 550 nm wavelengths, respectively. The FE-SEM and TEM studies revealed the presence of spherical particles with a smooth surface. The diameters of the AuNPs ranged from 49.32 to 77.29 nm; the diameters of the Bromelain-AuNPs ranged from 46.39 to 75.66 nm, as determined by the FE-SEM analysis. The TEM analysis indicated that the particles' sizes ranged from 7.40 to 15 nm for AuNPs and 14.51 nm for AuNPs-Bromelain. The XRD patterns revealed numerous diffraction peaks, indicating the crystal structure of the synthesised nanoparticles. FTIR spectrometry was employed to identify the functional groups in the synthesised nanoparticles. Zeta potential (ZP) measurements revealed that AuNPs had a zeta potential value of +0.1±0.4, and the zeta potential value for AuNPs-Bromelain was +1.2±3.0 mV.

Green synthesis of silver and gold nanoparticles in Callistemon viminalis extracts and their antimicrobial activities.

In the current study, the bottlebrush [Callistemon viminalis (Sol. ex Gaertn.) G. Don] plant was selected for the green synthesis of silver (Ag) and gold (Au) nanoparticles and to evaluate its antibacterial and antifungal activities. Phytochemical screening of C. viminalis confirmed the presence of alkaloids, anthraquinones, saponins, tannins, betacyanins, phlobatanins, coumarins, terpenoids, steroids, glycosides, and proteins. To characterize the synthesized Ag and Au NPs, UV-Visible spectroscopy, FTIR spectroscopy for functional group identification, field emission scanning electron microscopy (FE-SEM) for particle size, and elemental analysis were performed using EDX. The UV-Visible absorption spectra of the green-synthesized Ag and Au nanoparticles were found to have a maximum absorption band at 420 nm for Ag NPs and 525 nm for Au NPs. FE-SEM analysis of the synthesized NPs revealed a circular shape with a size of 100 nm. Elemental analysis was performed for the synthesis of Ag and Au NPs, which confirmed the purity of the nanoparticles. The greenly synthesized Ag and Au NPs were also evaluated for their anti-bacterial and anti-fungal activities, which exhibited prominent inhibition activities against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans, C. krusei, Aspergillus sp., and Trichoderma species. The highest zone of inhibition 15.5±0.75 and 15±0.85mm was observed for Ag NPs against E. coli and P. aeruginosa. Similarly, Trichoderma sp. and Aspergillus sp. were inhibited by Ag NPs up to 13.5±0.95 and 13±0.70mm. This work will open doors for the development of new antimicrobial agents using green chemistry.

Biogenic synthesis of silver, gold, and palladium nanoparticles using moringa oleifera seeds: exploring photocatalytic, catalytic, and antimicrobial activities

In this study, we explored the green synthesis of metal nanoparticles (Ag-NPs, Au-NPs, and Pd-NPs) using Moringa oleifera seed (MOS) extract, which is known for its nutrient density, antioxidant properties, anti-inflammatory effects, and potential benefits in managing cholesterol, blood sugar levels, as well as promoting digestion, skin, and hair health. The nanoparticles’ size was controlled by varying the concentration of MOS extract. The successful formation of Au-NPs and Ag-NPs was confirmed through surface plasmon resonance (SPR), while the absence of absorption at 420 nm indicated the reduction of Pd2+ ions to Pd0, affirming the synthesis of Pd-NPs. The nanoparticles exhibited mono-dispersed, spherical shapes with confirmed crystallinity. Sizes were determined as 28 nm for Pd-NPs, 5 nm for Au-NPs, and 19 nm for Ag-NPs. The MOS extract’s phenols and proteins played a crucial role in reducing and stabilising Ag-NPs, Au-NPs, and Pd-NPs. Notably, the synthesised nanoparticles demonstrated strong antimicrobial activity, particularly against Salmonella typhi, making them potential antibacterial agents. The catalytic efficiency of Au-NPs, Ag-NPs and Pd-NPs was studied using the reduction of 4-Nitrophenol (4-NP) by NaBH4 to 4-Aminophenol. Additionally, Au-NPs showed enhanced photocatalytic degradation rate constant and catalytic reaction rate constant of 0.0038/min and 0.261/min respectively, due to their small size and increased surface area. By combining a green synthesis approach with an in-depth analysis of properties and diverse applications, this study provides valuable insights into the immense potential of MOS-assisted metal nanoparticles for various technological and environmental advancements.

Dumbbell-like Au–Fe3O4 nanoparticles for magnetic hyperthermia

Dumbbell-shaped hybrid nanoparticles, consisting of gold and iron oxide (Au-Fe3O4 NPs), show promise for magnetic hyperthermia cancer therapy. However, conventional synthesis methods using toxic iron pentacarbonyl (Fe(CO)5) raise safety concerns. We propose a safer approach using triiron dodecacarbonyl (Fe3(CO)12) as a precursor. We synthesize these NPs by initially reducing gold (III) chloride trihydrate with a tert-butylamine-borane complex at room temperature, yielding Au NPs. These Au NPs are combined with a Fe3(CO)12 solution and heated to 300 °C for 1 hour, resulting in the desired dumbbell-shaped Au-Fe3O4 NPs. Characterization confirms their morphology, with average sizes of 5 nm for Au NPs and 15 nm for Fe3O4 NPs. Our systematic evaluation of hydrophilic-treated Au-Fe3O4 NPs (Ms=49.5 emu/g at 3T, 300K) demonstrates temperature increases beyond the therapeutic threshold of 45 °C (ΔT=8 °C) at higher field strengths (8.6–30.0 kA/m), highlighting their cancer treatment potential. Quantitative analysis reveals superb performance, with a specific absorption rate (SAR) of 60.0 W/g and intrinsic loss power (ILP) of 0.25 nHm2kg−1 at the maximum field strength. These findings emphasize the significant potential of our dumbbell-shaped Au–Fe3O4 NPs for magnetic hyperthermia.

Green Synthesis of Gold and Silver Nanoparticles Using Invasive Alien Plant Parthenium hysterophorus and Their Antimicrobial and Antioxidant Activities

Due to the high energy demands and environmental hazards of physical and chemical methods, it is now essential to produce nanoparticles using plant sources as reducing and stabilizing agents. In this study, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were biosynthesized using an aqueous extract of Parthenium hysterophorus aerials as a reducing and stabilizing agent. The synthesized nanoparticles were characterized using UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and transmission electron Microscopy (TEM). UV–Vis spectroscopy indicates that the peaks of AgNPs and AuNPs are at 422 and 538 nm, respectively. The results of the DLS analysis showed that both Au and AgNPs are monodispersed and stable and have mean hydrodynamic sizes of 53.55 nm and 68.12 nm, respectively. According to an XRD analysis, the generated AgNPs and AuNPs are face-centered cubic crystals with average crystalline diameters of 33.4 nm and 30.5 nm, respectively. TEM image depicted that the synthesized NPs mainly have spherical shapes with particle size in the range of 3.41–14.5 nm for AuNPs and 5.57–26.3 nm for AgNPs. These biologically produced AuNPs and AgNPs were investigated for their antibacterial, antifungal, and antioxidant effects. Both AuNPs and AgNPs were found to strongly influence the growth of bacterial pathogens, with a maximum zone of 22.3 and 19.7 mm in Escherichia coli and a minimum zone of 11.7 and 10.3 mm in Salmonella enterica, respectively. The synthesized AuNPs and AgNPs reduce the numbers of viable fungi by 51.06% and 47.87%, respectively. The DPPH (2,2-diphenyl-1-picrylhydrazyl) assay revealed that the synthesized AuNPs and AgNPs have significant radical scavenging ability with 88.75% and 86.25% inhibition and 33.62 μg/mL and 42.86 μg/mL of IC50, respectively. Therefore, an aqueous extract of aerial parts of P. hysterophorus can be a suitable precursor for synthesizing AuNPs and AgNPs, with numerous applications. Due to their smaller size, AuNPs have better antimicrobial and antioxidant activities than AgNPs. This study supports the conservation by a utilization strategy of invasive alien plant species control and management (such as P. hysterophorus) for biodiversity conservation and environmental sustainability.

Local anesthetic, anti-inflammatory and analgesic activities of nanoparticles green-formulated by plant extract

• The results revealed a spherical morphology in the range size of 10–50 nm for AuNPs. • The IC50 of AuNPs and BHT against DPPH were 18 and 12 µg/mL, respectively. • It seems the recent nanoparticle may be use as a novel therapeutic drug in future. In the current research, we decided to formulate gold nanoparticles in aqueous medium using plant leaf aqueous extract as a new therapeutic drug for determining the local anesthetic, anti-inflammatory and analgesic activities in the in vivo condition. The common chemical tests i.e., UV–Visible Spectroscopy (UV–Vis), Transmission Electron Microscopy (TEM), and Fourier Transformed Infrared Spectroscopy (FT‐IR) were used for characterizing of nanoparticles. To survey the cytotoxicity properties of nanoparticles, MTT assay was used on the human normal cell lines. Analgesic activity was tested in mice using various doses orally. Acetic acid-induced writhing episodes were significantly and dose-dependently reduced. The local anesthetic activity were tested in frog and guinea pig models, and it was seen that in both animals, the nanoparticle produces significant local anesthetic activity. At the same dose, its anti-inflammatory activity was also tested. Carrageenin-induced paw edema in mice was significantly reduced after oral administration. It seems the recent nanoparticle may be use as a novel therapeutic drug with local anesthetic, anti-inflammatory and analgesic activities in future.

Controlled synthesis of gemini surfactant-capped gold nanoparticles. Gemini structure-nanoparticle properties relationship study

Gold nanoparticles were prepared by the method of chemical reduction utilising sodium borohydride as reducing agent and stabilised with bisammonium gemini surfactants with variable length of polymethylene spacer. Physico-chemical investigations indicated the presence of plasmon resonance peaks in the wavelength range 507–544 nm for all investigated Au nanodispersions. The nanoparticle size analysis shows the relationship between the size of gold nanoparticles and the spacer length of stabilising gemini molecules. The strong aggregation tendency of gemini surfactants with short polymethylene spacer composed of 2–4 methylene units in aqueous solutions may be responsible for the formation of clusters of gold nanoparticles which results in the observed large hydrodynamic size of nanoparticle clusters at the surfactants concentrations below the CMC. At higher surfactant-to-gold molar ratio values, clusters disintegration occurs and the decrease in size of the nanoparticles is observed. The shape of gold nanoparticles was found to be spherical and polyhedral, as evidenced by the SEM images. The size values varied between 30–60 nm and 10–15 nm for AuNPs capped with gemini molecules with short and medium/long spacer, respectively. Gold nanoparticles are strongly positively charged, with positive zeta potential values being in the interval +44 to +90 mV in the whole analysed region of molar ratio values and surfactant spacer length. The biological experiments indicate a dependence of biological activity of gold nanoparticles on the structural parameter (spacer length) of stabilising gemini molecules. Both cytotoxicity and anti-inflammatory activity of gold nanoparticles were found to increase with the increasing gemini spacer length up to 12 methylene groups in the spacer.

Phytofabrication of gold and bimetallic gold-silver nanoparticles using water extract of wheatgrass (Triticum aestivum), their characterization and comparative assessment of antibacterial potential

In the present study, gold (AuNPs) and gold-silver bimetallic nanoparticles (Au-Ag BMNPs) were fabricated by using water extract of leaves of Triticum aestivum - a crop plant, and their bactericidal potency was checked against selected pathogenic bacterial strains. The phytofabricated AuNPs and BMNPs were analyzed for their physical attributes using UV–Visible and Fourier transformed infrared spectroscopy, Dynamic light scattering, High-resolution transmission electron microscopy, Energy-dispersive X-ray spectroscopy. HRTEM analysis revealed that both kinds of NPs were highly crystalline in nature and of spherical and oval-shaped. AuNPs size was found in the range of 5-40 nm, whereas BMNPs showed their size in the range of 5-30 nm. HRTEM results were corroborated by DLS results which revealed the average hydrodynamic diameter of AuNPs and BMNPs in the range of 29.08 and 26.56 nm, respectively. UV-visible spectroscopy showed high-intensity single spectral peaks at 540 and 480 nm for AuNPs and BMNPs, respectively. FTIR analysis demonstrated that protein, flavanones, hydroxyl, carboxylate groups, and reducing sugars were responsible for reducing and capping of both NPs. Bactericidal efficiency of synthesized NPs was evaluated using agar-well diffusion and XTT-colorimetric assays against K. pneumoniae, S. typhimurium, E. aerogenes, E. coli, M. luteus, S. aureus, S. mutans and S. epidermidis. K. pneumonia and S. typhimurium were found to be the most sensitive bacteria towards BMNPs-mediated (MIC: 400 µg/ml) and AuNPs-mediated toxicity (MIC: 800 µg/ml). It was observed that BMNPs generally possessed more powerful bactericidal effect against all bacterial strains in comparison to AuNPs. MIC and MBC values were observed in the concentration range of 400 µg/ml-1.5 mg /ml for different bacterial strains. Furthermore, it was demonstrated that phytosynthesized AuNPs have their own bactericidal effect, but at higher concentrations (>100 µg/ml), and bactericidal effect of BMNPs was due to the synergistic effect of both Ag and Au ions, which was also observed to be concentration-dependent.

Rapid formation methods of arrays of randomly distributed Au and Ag nanoparticles, their morphologies and optical characteristics

By the method of rapid radiation heating (at a speed of 20-25 K/s) of Au and Ag films with a thickness of 4-35 nm to temperatures of 573-693 K in air and in the process of vacuum deposition of silver on heated (up to 700 K at a heating rate of 10 K/s ) glass substrates formed Au and Ag NPs arrays with nanoparticle sizes from several tens to hundreds of nanometers, the position λSPR of which is in the range of 520-597 nm for Au NPs and 424-509 nm for Ag NPs. It is established that the average size of nanoparticles depends on the thickness of gold and silver films and the annealing temperature. The results testify that glass substrates with arrays of randomly distributed gold NPs can be used as effective SERS-substrates for the investigation of Raman spectra of nanosized (50-100 nm) chalcogenide films.

Green Synthesis of Gold and Silver Nanoparticles by Using Amorphophallus paeoniifolius Tuber Extract and Evaluation of Their Antibacterial Activity.

In this report, we discussed rapid, facile one-pot green synthesis of gold and silver nanoparticles (AuNPs and AgNPs) by using tuber extract of Amorphophallus paeoniifolius, and evaluated their antibacterial activity. AuNPs and AgNPs were synthesized by mixing their respective precursors (AgNO3 and HAuCl4) with tuber extract of Amorphophallus paeoniifolius as the bio-reducing agent. Characterization of AuNPs and AgNPs were confirmed by applying UV-vis spectroscopy, field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDS). From UV-vis characterization, surface plasmon resonance spectra were found at 530 nm for AuNPs and 446 nm for AgNPs. XRD data confirmed that both synthesized nanoparticles were face-centered cubic in crystalline nature, and the average crystallite sizes for the assign peaks were 13.3 nm for AuNPs and 22.48 nm for AgNPs. FTIR data evaluated the characteristic peaks of different phytochemical components of tuber extract, which acted as the reducing agent, and possibly as stabilizing agents. The antibacterial activity of synthesized AuNPs and AgNPs were examined in Muller Hinton agar, against two Gram-positive and four Gram-negative bacteria through the disc diffusion method. AuNPs did not show any inhibitory effect, while AgNPs showed good inhibitory effect against both Gram-positive and Gram-negative bacteria.

Ultrastructural Features of Gold Nanoparticles Interaction with HepG2 and HEK293 Cells in Monolayer and Spheroids.

Use of multicellular spheroids in studies of nanoparticles (NPs) has increased in the last decade, however details of NPs interaction with spheroids are poorly known. We synthesized AuNPs (12.0 ± 0.1 nm in diameter, transmission electron microscopy (TEM data) and covered them with bovine serum albumin (BSA) and polyethyleneimine (PEI). Values of hydrodynamic diameter were 17.4 ± 0.4; 35.9 ± 0.5 and ±125.9 ± 2.8 nm for AuNPs, AuBSA-NPs and AuPEI-NPs, and Z-potential (net charge) values were −33.6 ± 2.0; −35.7 ± 1.8 and 39.9 ± 1.3 mV, respectively. Spheroids of human hepatocarcinoma (HepG2) and human embryo kidney (HEK293) cells (Corning ® spheroid microplates CLS4515-5EA), and monolayers of these cell lines were incubated with all NPs for 15 min–4 h, and fixed in 4% paraformaldehyde solution. Samples were examined using transmission and scanning electron microscopy. HepG2 and HEK2893 spheroids showed tissue-specific features and contacted with culture medium by basal plasma membrane of the cells. HepG2 cells both in monolayer and spheroids did not uptake of the AuNPs, while AuBSA-NPs and AuPEI-NPs readily penetrated these cells. All studied NPs penetrated HEK293 cells in both monolayer and spheroids. Thus, two different cell cultures maintained a type of the interaction with NPs in monolayer and spheroid forms, which not depended on NPs Z-potential and size.

Fabrication of Nanostructured Polyamic Acid Membranes for Antimicrobially Enhanced Water Purification

Water scarcity and quality challenges facing the world can be alleviated by Point-of-Use filtration devices (POU). The use of filtration membranes in POU devices has been limited largely because of membrane fouling, which occurs when suspended solids, microbes, and organic materials are deposited on the surface of filtration membranes significantly decreasing the membrane lifespan, thereby increasing operation costs. There is need therefore to develop filtration membranes that are devoid of these challenges. In this work, nanotechnology was used to fabricate nanostructured polyamic acid (nPAA) membranes, which can be used for microbial decontamination of water. The PAA was used as support and reducing agent to introduce silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) with antimicrobial properties. The nPAA membranes were fabricated via thermal and wet phase inversion technique and then tested against Escherichia coli and Staphylococcus aureus following standard tests. The resulting nanoparticles exhibited excellent dispersibility and stability as indicated by the color change of the solution and increments of optical density at 415 nm for AgNPs and 520 nm for AuNPs. The wet phase inversion process used produced highly porous, strong, and flexible nPAA membranes, which showed well-dispersed spherical AuNPs and AgNPs whose rough average size was found to be 35 nm and 25 nm, respectively. The AgNPs demonstrated inhibition for both gram positive E. coli and gram negative S. aureus, with a better inhibitory activity against S. aureus. A synergistic enhancement of AgNPs antimicrobial activity upon AuNPs addition was demonstrated. The nPAA membranes can thus be used to remove microbials from water and can hence be used in water purification.

Design, Synthesis, Computational and Biological Evaluation of 4-Amino-3,5-dimercapto-1,2,4-triazole Surface Functionalized Gold Nanoparticles

Gold nanoparticles (AuNPs) are an obvious choice for rapid advance in nanotechnology due to their amenability of synthesis, functionalization and less toxicity. Functionalization of AuNP surface with 4-amino-3,5-dimercapto-1,2,4-triazole (ADMT) ligand as ADMT-AuNPs was investigated with the aim to probe the suitability of innovative product to develop new antibacterial and anticancer strategies. Various characterization studies like UV-spectra, Zeta size, Zeta potential, XRD, SEM, TEM and FTIR results of AuNPs and ADMT-AuNPs have been performed to study the structural and electronic properties. The studies revealed that the functionalized nanoparticles are highly crystalline in nature with the sizes ranging between 20-22 and 50-55 nm for AuNPs and ADMT-AuNPs, respectively with FCC structures. The characterization data reveals that the synthesized nanoparticles are stable and presence of strong interactions between the metallic surface and the organic ligand. Further, ADMT-AuNPs showed good antibacterial activity against Gram-positive and Gram-negative bacteria. MTT assay exhibited the cell viability with an IC50 value of 45.32 % v/v for ADMT-AuNPs against breast adenocarcinoma (MCF-7) cell lines. Molecular characterization i.e., in silico docking analysis helped in identifying and organizing the structural similarity/diversity at the molecular level. The in silico study indicated that the structure S1a has good glide score and glide energy for H-bonding among the possible conformations against bacterial and breast cancer protein. Molecular docking studies confirmed the introduction of conformational changes that are essential to surpass the potential energy barriers of ADMT-AuNPs for biocompatibility and proved that they hold a promising future in the medical field.

تحضیرمتراكبات Au/Ag النانویة بواسطة التبخر الانفجاري للیزرالنبضي في الماء واستخدامها في السيطرة على فعالية انزيم AIP في دم الانسان

تم الحصول على محاليل مائيه غرويه عالقه لمتراكبات الفضة والذهب النانوية بأستخدام طريقة التبخر الانفجاري لقطع معدنية فائقة النقاوة من الذهب والفضة المغموره في ماء لاأيوني ثنائي التقطير وبأستخدام طولين موجيين 1064nm,532nmمن ليزر الياك النبضي بطاقة 100-900mj)). طيف الامتصاص لرنين البلازموني تم الحصول علية بأستخدام مطياف الاشعة المرئية-فوق البنفسجية دعمت النتائج باستخدام تقنية الاشعة السينية والمجهر الالكتروني النافذ. اظهرت اطياف الامتصاص الاشعة المرئية-فوق البنفسجية قمة حادة لكل معدن (400nm)للفضة (525nm) للذهب واظهرت الفحوصات تولد جسيمات نانوية تراوحت قياسها من (5-45nm) للفضة و(8-55nm)للذهب و(10-170nm)للمتراكب فضة- ذهب وبشكل عام بينت الفحوصات بأن الجسيمات النانوية اخذت الشكل الكروي وهيئة بلورية تدعى المكعب مركزي الوجة يعرف ب .(fcc). ان هذا العمل يمثل دراسة تأثير عدد نبضات الليزرعلى خواص سبائك الذهب والفضة النانوية وكذلك دراسة التأثير البايولوجي لهذه السبائك على فعالية انزيم الالكالاين فوسفاتيزفي دم الانسان.

Synthesis and UV−Visible spectroscopy study of core−shell gold−palladium nanoparticles by iterative seeding of citrate

In this study, gold and palladium nanoparticles (Au NPs and Pd NPs) were successfully synthesized by the iterative seeding of citrate and ascorbate, respectively. UV− visible spectroscopy results revealed that Au NPs exhibit plasmonic resonance peaks at 540−560 nm, while Pd NPs exhibit peaks at 220 nm. Transmission electron microscopy images revealed particle size distributions of 19.3 ± 4.2 nm and 31.9 ± 6.1 nm for Au NPs and Pd NPs, respectively. Larger sizes were observed for palladium nanoparticles because of their aggregation caused by the deficiency of the capping agent, while gold particles exhibited size stability. Furthermore, gold-palladium (AuPd) nanoflower particles were synthesized by the iterative citrate seeding of Pd on the Au NP surface.

Starch-mediated synthesis of mono- and bimetallic silver/gold nanoparticles as antimicrobial and anticancer agents.

Background and aimBimetallic silver/gold nanosystems are expected to significantly improve therapeutic efficacy compared to their monometallic counterparts by maintaining the general biocompatibility of gold nanoparticles (AuNPs) while, at the same time, decreasing the relatively high toxicity of silver nanoparticles (AgNPs) toward healthy human cells. Thus, the aim of this research was to establish a highly reproducible one-pot green synthesis of colloidal AuNPs and bimetallic Ag/Au alloy nanoparticles (NPs; Ag/AuNPs) using starch as reducing and capping agent.MethodsThe optical properties, high reproducibility, stability and particle size distribution of the colloidal NPs were analyzed by ultraviolet (UV)–visible spectroscopy, dynamic light scattering (DLS) and ζ-potential. The presence of starch as capping agent was determined by Fourier transform infrared (FT-IR) spectroscopy. The structural properties were studied by X-ray diffraction (XRD). Transmission electron microscopy (TEM) imaging was done to determine the morphology and size of the nanostructures. The chemical composition of the nanomaterials was determined by energy-dispersive X-ray spectroscopy (EDS) and inductively coupled plasma mass spectrometry (ICP-MS) analysis. To further study the biomedical applications of the synthesized nanostructures, antibacterial studies against multidrug-resistant (MDR) Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) were conducted. In addition, the NPs were added to the growth media of human dermal fibroblast (HDF) and human melanoma cells to show their cytocompatibility and cytotoxicity, respectively, over a 3-day experiment.ResultsUV–visible spectroscopy confirmed the highly reproducible green synthesis of colloidal AuNPs and Ag/AuNPs. The NPs showed a face-centered cubic crystal structure and an icosahedral shape with mean particle sizes of 28.5 and 9.7 nm for AuNPs and Ag/AuNPs, respectively. The antibacterial studies of the NPs against antibiotic-resistant bacterial strains presented a dose-dependent antimicrobial behavior. Furthermore, the NPs showed cytocompat-ibility towards HDF, but a dose-dependent anticancer effect was found when human melanoma cells were grown in presence of different NP concentrations for 72 hours.ConclusionIn this study, mono- and bimetallic NPs were synthesized for the first time using a highly reproducible, environmentally friendly, cost-effective and quick method and were successfully characterized and tested for several anti-infection and anticancer biomedical applications.

Phytosynthesis of gold and silver nanoparticles enhance in vitro antioxidant and mitostimulatory activity of Aconitum toxicum Reichenb. rhizomes alcoholic extracts

Extracts obtained from different plant species proved to be a valuable tool in various biomedical applications. In the same time, the phytosynthesis of noble metal nanoparticles represents an already well-established route for obtaining nanoparticles with biological activity. The present paper studies the antioxidant activity and the cytogenetic effects of the alcoholic extracts from rhizomes of Aconitum toxicum Rchb., before and after the phytosynthesis of gold and silver nanoparticles, on the meristematic root cells of Allium cepa L., and on the general mitotic index and the progression rate through the mitotic phases, respectively, as well as on the genetic material organized in chromosomes. The extracts were characterized in terms of total polyphenolics content (1.49% and, respectively, 2.29%) and aconitine content (by HPLC – 4.891 mg/L and, respectively, 18.211 mg/L), while the phytosynthesis of metallic nanoparticles was monitored by UV–Vis spectrometry, X-ray diffraction, X-ray fluorescence and electron microscopy. Both the extracts and the obtained nanoparticles were evaluated for antioxidant potential (the antioxidant activity ranging between 78% and 84.32%) and cytogenetic effects. The obtained results prove the phytosynthesis of AgNPs and AuNPs with dimensions ranging from 9 nm to 15 nm for AuNPs, respectively from 53 nm to 67 nm for AgNPs. The extracts obtained from rhizomes of A. toxicum Rchb. induced mitotic stress, as well as a series of nuclear and mitotic aberrations. The biosynthesis of AgNPs and AuNPs intensified the antioxidant and mitostimulatory activity of the extracts.

Fabrication of Paper Sensor for Rapid Screening of Nanomaterial Synthesizing Potential of Plants

Numerous reports are available for the use of plant extract in nanoparticles synthesis. The traditional methodologies adopted for analyzing nanosynthesis potential of plant materials is tedious and time-consuming. Rapid, selective, low-cost and easy protocols for on-site detection of nanoparticles synthesizing potential of plant extract have tremendous potential in nanotechnology. In the present study, a simple and selective nanoparticles synthesis screening approach is developed by coating metal salts (precursor for metal nanoparticles) on an inert paper strip and allowing them to react with test plants extract such as plant latex, whose nanosynthesis potential have to be screened. The visual color change of paper strip after reaction of metal salts with latex is the ultimate colorimetric endpoint indicating the formation of nanoparticles. Diverse nanoanalysis techniques qualitatively confirmed the nanoparticles formed on the paper strip. UV–visible spectroscopy exhibit characteristic absorption peaks for AuNPs and AgNPs at around 520 and 430 nm. Scanning electron microscopy confirms the size of 87 and 114 nm for AuNPs and AgNPs. The simplicity, selectivity and rapid response make this approach a promising layman-friendly, on-site useful detection tool. This screening platform can rapidly screen diverse plant species for their capacity to fabricate nanoparticle to select most potent species.

Density-matrix evaluation of the enhancement to resonant Raman scattering and fluorescence of molecules confined in metallic nanoparticle dimers

In the present work we study the surface-enhanced resonant Raman scattering (SERRS) and fluorescence (SEF) spectra of a general model molecule confined in metallic dimers consisting of Ag, Au and hybrid AuAg nanoparticles (NPs). The electromagnetic (EM) enhancement factors were simulated by the generalized Mie scatting method and the scattering cross section of the molecules were obtained by density-matrix calculations. The influence of the size of the NPs and the separation between the dimer on the Raman scattering and fluorescence were systematically studied and analyzed in detail. It was found that the SERRS mainly related to EM enhancement and the SEF depended on the competition between EM enhancement and quantum yield, both of which could be controlled by tuning the radius and separation of the metallic dimers. The optimal radius of the NPs for SERRS were found to be around 30 nm for AgNPs, 40 nm for AuNPs and 50 nm for hybrid AuAgNPs. The strongest Raman enhancement as predicted by the theoretical simulations were 6.2 × 1010, 1.5 × 107 and 5.2 × 108 for the three types of structures, respectively. These results could offer valuable information for the design of metallic substrates for surface enhanced Raman and fluorescence measurements.

Platanus orientalis Leaf Mediated Rapid Synthesis of Catalytic Gold and Silver Nanoparticles

In an attempt to synthesize novel catalytic gold (AuNPs) and silver nanoparticles (AgNPs) we have used Platanus orientalis leaf extract for both reduction and capping. The synthesis was rapid which completed by 5 h as indicated by change in colour and development of prominent peak at 540 nm for AuNPs and 440 nm for AgNPs, as revealed by UV-visible spectroscopy. The phytogenic nanoparticles showed exotic shapes which included triangles, spheres, hexagons and pentagons as analyzed by high resolution transmission electron microscopy. The optimized processing parameters like salt concentration (1 mM concentration of HAuCl4 and 4 mM of AgNO3) and the reaction temperature (50°C) led to faster nanoparticles synthesis. Energy dispersive spectra and X-ray diffraction studies confirmed the elemental gold and silver in AuNPs and AgNPs. Detailed phytochemical characterization using biochemical techniques and gas chromatography mass spectrometry indicated the predominance of ascorbic acid, citric acid, reducing sugars and even starch which may together lead to simultaneous synthesis and capping. Further, AuNPs and AgNPs catalyzed the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using NaBH4 with apparent rate constants of 1.908 × 10-4 min-1 and 3.071 × 10-4 min-1, respectively.