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Gurunathan S.,Konkuk University | Gurunathan S.,GS Institute of Bio and Nanotechnology
Arabian Journal of Chemistry | Year: 2014

Emergence of antibiotic resistance has become an increasingly important public health issue. Although several new antibiotics have been developed in the last few decades, none of them show improved activity against multidrug-resistant bacteria. Silver nanoparticles (AgNPs) have long been known for their broad-spectrum antibacterial effects. The development of a rapid, dependable, simple, cost-effective, biocompatible, and environmentally friendly method to synthesize nanoparticles is an essential aspect of current biomedical research. This paper describes the extracellular biochemical synthesis of AgNPs using supernatants from . Bacillus cereus cultures and characterization of the synthesized AgNPs, using several analytical techniques. The nanoparticles showed a maximum absorbance at 420. nm in ultraviolet-visible spectra. Particle size analysis by dynamic light scattering and transmission electron microscopy revealed the formation of homogeneous and well-dispersed nanoparticles with an average size of 10. nm. We investigated the dose-dependent antibacterial activity of AgNPs against . Escherichia fergusonii and . Streptococcus mutans. In addition, the efficiency of AgNPs with various broad-spectrum antibiotics against these test strains was evaluated. The results show that the combination of antibiotics with AgNPs has significant antimicrobial effects. The greatest enhancement was observed with gentamycin and vancomycin against . E. fergusonii and . S. mutans, respectively. This work supports that AgNPs can be used to enhance the activity of existing antibiotics against Gram-negative and Gram-positive bacteria. © 2014 The Author. Source


Gurunathan S.,Konkuk University | Gurunathan S.,GS Institute of Bio and Nanotechnology
Journal of Industrial and Engineering Chemistry | Year: 2015

This study was aimed at investigating the toxicological effects of GO on beneficial Bacillus soil microbes. Five bacterial isolates screened from the rhizosphere of a common pulse-growing agricultural field were identified as Bacillus marisflavi, Bacillus cereus, Bacillus subtilis, Bacillus megaterium, and Bacillus mycoides. To study the effect of GO under in vitro conditions, GO was prepared and characterized by various analytical techniques. Our results suggest that GO decreases cell viability in a concentration- and time-dependent manner by regulating biochemical changes and demonstrate that GO nanoparticles can negatively impact beneficial bacterial communities in the soil. © 2015 The Korean Society of Industrial and Engineering Chemistry. Source


Gurunathan S.,Konkuk University | Gurunathan S.,GS Institute of Bio and Nanotechnology
Journal of Industrial and Engineering Chemistry | Year: 2015

Here we report a simple, fast, cost-effective, and nonpolluting approach for synthesis of silver nanoparticles (AgNPs) using leaf extract of Typha angustifolia. We demonstrate the dose-dependent antibacterial activity of AgNPs and different antibiotics against Escherichia coli and Klebsiella pneumoniae. Furthermore, we demonstrate the efficacy of AgNPs in combination with various broad-spectrum antibiotics against E. coli and K. pneumoniae. The results show that combinations of antibiotics and AgNPs show significant antimicrobial effects at sub-lethal concentrations of the antibiotics. These data suggest that combinations of antibiotics and AgNPs can be used therapeutically for the treatment of infectious diseases. © 2015 The Korean Society of Industrial and Engineering Chemistry. Source


Gurunathan S.,Konkuk University | Gurunathan S.,GS Institute of Bio and Nanotechnology | Han J.W.,Konkuk University | Park J.H.,Konkuk University | Kim J.H.,Konkuk University
International Journal of Nanomedicine | Year: 2014

Background: Recently, graphene and graphene-related materials have attracted much attention due their unique properties, such as their physical, chemical, and biocompatibility properties. This study aimed to deter mine the cytotoxic effects of graphene oxide (GO) that is reduced biologically using Ganoderma spp. mushroom extracts in MDA-MB-231 human breast cancer cells. Methods: Herein, we describe a facile and green method for the reduction of GO using extracts of Ganoderma spp. as a reducing agent. GO was reduced without any hazardous chemicals in an aqueous solution, and the reduced GO was characterized using a range of analytical procedures. The Ganoderma extract (GE)-reduced GO (GE-rGO) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, dynamic light scattering, scanning electron microscopy, Raman spectroscopy, and atomic force microscopy. Furthermore, the toxicity of GE-rGO was evaluated using a sequence of assays such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation in human breast cancer cells (MDA-MB-231). Results: The preliminary characterization of reduction of GO was confirmed by the red-shifting of the absorption peak for GE-rGO to 265 nm from 230 nm. The size of GO and GE-rGO was found to be 1,880 and 3,200 nm, respectively. X-ray diffraction results confirmed that reduction processes of GO and the processes of removing intercalated water molecules and the oxide groups. The surface functionalities and chemical natures of GO and GE-rGO were confirmed using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface morphologies of the synthesized graphene were analyzed using high-resolution scanning electron microscopy. Raman spectroscopy revealed single- and multilayer properties of GE-rGO. Atomic force microscopy images provided evidence for the formation of graphene. Furthermore, the effect of GO and GE-rGO was examined using a series of assays, such as cell viability, membrane integrity, and reactive oxygen species generation, which are key molecules involved in apoptosis. The results obtained from cell viability and lactate dehydrogenase assay suggest that GO and GE-rGO cause dose-dependent toxicity in the cells. Interestingly, it was found that biologically derived GE-rGO is more toxic to cancer cells than GO. Conclusion: We describe a simple, green, nontoxic, and cost-effective approach to producing graphene using mushroom extract as a reducing and stabilizing agent. The proposed method could enable synthesis of graphene with potential biological and biomedical applications such as in cancer and angiogenic disorders. To our knowledge, this is the frst report using mushroom extract as a reducing agent for the synthesis of graphene. Mushroom extract can be used as a biocatalyst for the production of graphene. © 2014 Gurunathan et al. Source


Gurunathan S.,Konkuk University | Gurunathan S.,GS Institute of Bio and Nanotechnology | Han J.W.,Konkuk University | Park J.H.,Konkuk University | Kim J.-H.,Konkuk University
Nanoscale Research Letters | Year: 2014

Gold nanoparticles (AuNPs) are a fascinating class of nanomaterial that can be used for a wide range of biomedical applications, including bio-imaging, lateral flow assays, environmental detection and purification, data storage, drug delivery, biomarkers, catalysis, chemical sensors, and DNA detection. Biological synthesis of nanoparticles appears to be simple, cost-effective, non-toxic, and easy to use for controlling size, shape, and stability, which is unlike the chemically synthesized nanoparticles. The aim of this study was to synthesize homogeneous AuNPs using pharmaceutically important Ganoderma spp. We developed a simple, non-toxic, and green method for water-soluble AuNP synthesis by treating gold (III) chloride trihydrate (HAuCl4) with a hot aqueous extract of the Ganoderma spp. mycelia. The formation of biologically synthesized AuNPs (bio-AuNPs) was characterized by ultraviolet (UV)-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the biocompatibility of as-prepared AuNPs was evaluated using a series of assays, such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation (ROS) in human breast cancer cells (MDA-MB-231). The color change of the solution from yellow to reddish pink and strong surface plasmon resonance were observed at 520 nm using UV-visible spectroscopy, and that indicated the formation of AuNPs. DLS analysis revealed the size distribution of AuNPs in liquid solution, and the average size of AuNPs was 20 nm. The size and morphology of AuNPs were investigated using TEM. The biocompatibility effect of as-prepared AuNPs was investigated in MDA-MB-231 breast cancer cells by using various concentrations of AuNPs (10 to 100 μM) for 24 h. Our findings suggest that AuNPs are non-cytotoxic and biocompatible. To the best of our knowledge, this is the first report to describe the synthesis of monodispersed, biocompatible, and soluble AuNPs with an average size of 20 nm using Ganoderma spp. This study opens up new possibilities of using an inexpensive and non-toxic mushroom extract as a reducing and stabilizing agent for the synthesis of size-controlled, large-scale, biocompatible, and monodispersed AuNPs, which may have future diagnostic and therapeutic applications. © 2014 Gurunathan et al.; licensee Springer. Source

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