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BIOSYNTHESIS OF GOLD NANOPARTICLES BY FOOD ORIGIN CITROBACTER FREUNDII
Abstract
Gold nanoparticles (AuNPs) biosynthesized for first time worldwide using food origin isolates of Citrobacter freundii. The biosynthesis of AuNPs was firstly observed by visual remark and then characterized with the help of different characterization techniques such as atomic force microscopy (AFM) analysis, Uv-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR) analysis and scanning Electron Microscope (SEM), which revealed that the biosynthesized AuNPs were roughly spherical and poly-dispersed within size range of 30-60 nm. Optimization of AuNPs biosynthesis by C. freundii was performed for several parameters (concentration of cell filtrate, temperature, pH and concentration gold salt) and the results revealed that undiluted cell filtrate, temperature 60°C, pH range from 5 to 9 and 2mM gold salt concentration were the optimum conditions for AuNPs biosynthesis by C. freundii.
... Food origin Citrobacter freundii isolate (C2) was isolated from chicken meat samples by pour plate method and identified using cultural characteristics, biochemical tests and the identification to the species level was completed by Vitek-2 system and this identification was confirmed by sequencing of the 16 s r RNA in a previous study (8). Gold nanoparticles were biosynthesized using C. freundii isolate (C2) in an optimized condition in order to achieve the finest AuNps with a diameter range (30-60) nm. and the biosynthesized gold nanoparticles were characterized by visual observation and then characterized using various characterization techniques: Uv-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR) analysis, atomic force microscopy (AFM) analysis and scanning Electron Microscope (SEM) previously to this research (9). ...
Background: Antibiotic resistance is a life threating problem and the need for an alternative is increasing worldwide. Objective of this study is: Detecting the combination effect of AuNps with Amoxicillin/clavulanate (AMC) antibiotic against antibiotic resistant clinical bacterial isolates. Materials and methods: Gold nanoparticles were biosynthesized using food origin Citrobacter freundii isolate (C2) which was isolated from chicken meat samples by pour plate method and identified using cultural characteristics, biochemical tests and the identification to the species level was completed by Vitek-2 system and this identification was confirmed by sequencing of the 16 s r RNA. The biosynthesis of gold nanoparticles was optimized in order to achieve the finest AuNps with a diameter range (30-60) nm. and the biosynthesized gold nanoparticles were characterized by visual observation and then characterized using various characterization techniques: Uv-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR) analysis, atomic force microscopy (AFM) analysis and scanning Electron Microscope (SEM). The combination effect of AuNps with AMC antibiotic was detected against clinical bacterial isolates. Results: The results revealed the biosynthesized AuNPs were roughly spherical and poly-dispersed, and they were highly effective with concentration (62.5 µg/ml) that inhibit the bacterial growth, MIC values of AMC antibiotic against clinical isolates were determined as 500 µg/ml, while the combination of gold nanoparticles and AMC had wide spectrum of antibacterial activity against different isolates of the bacteria that used in this study. Conclusion: There was a significant synergistic effect between the biosynthesized gold nanoparticles when used in combination with antibiotic where the minimum inhibitory concentrations of the combination (AuNps/AMC) were less than its concentration when each of them (AuNps) or (AMC) used separately.
... Food origin Citrobacter freundii isolate (C2) was isolated from chicken meat samples by pour plate method and identified using cultural characteristics, biochemical tests and the identification to the species level was completed by Vitek-2 system and this identification was confirmed by sequencing of the 16 s r RNA in a previous study (8). Gold nanoparticles were biosynthesized using C. freundii isolate (C2) in an optimized condition in order to achieve the finest AuNps with a diameter range (30-60) nm. and the biosynthesized gold nanoparticles were characterized by visual observation and then characterized using various characterization techniques: Uv-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR) analysis, atomic force microscopy (AFM) analysis and scanning Electron Microscope (SEM) previously to this research (9). ...
Background: Antibiotic resistance is a life threating problem and the need for an alternative is increasing worldwide. Objective of this study is: Detecting the combination effect of AuNps with Amoxicillin/clavulanate (AMC) antibiotic against antibiotic resistant clinical bacterial isolates. Materials and methods: Gold nanoparticles were biosynthesized using food origin Citrobacter freundii isolate (C2) which was isolated from chicken meat samples by pour plate method and identified using cultural characteristics, biochemical tests and the identification to the species level was completed by Vitek-2 system and this identification was confirmed by sequencing of the 16 s r RNA. The biosynthesis of gold nanoparticles was optimized in order to achieve the finest AuNps with a diameter range (30-60) nm. and the biosynthesized gold nanoparticles were characterized by visual observation and then characterized using various characterization techniques: Uv-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR) analysis, atomic force microscopy (AFM) analysis and scanning Electron Microscope (SEM). The combination effect of AuNps with AMC antibiotic was detected against clinical bacterial isolates. Results: The results revealed the biosynthesized AuNPs were roughly spherical and poly-dispersed, and they were highly effective with concentration (62.5 µg/ml) that inhibit the bacterial growth, MIC values of AMC antibiotic against clinical isolates were determined as 500 µg/ml, while the combination of gold nanoparticles and AMC had wide spectrum of antibacterial activity against different isolates of the bacteria that used in this study. Conclusion: There was a significant synergistic effect between the biosynthesized gold nanoparticles when used in combination with antibiotic where the minimum inhibitory concentrations of the combination (AuNps/AMC) were less than its concentration when each of them (AuNps) or (AMC) used separately.
Metal nanoparticles have gained considerable attention as versatile nanomaterials due to their size- and shape- dependent electrical, electronic, optical, and catalytic properties. Various physical and chemical approaches have been investigated for synthesizing metal nanoparticles, specifically gold nanoparticles due to their biocompatibility, antioxidant potentials, catalytic activity, and other promising characteristics. As the chemical based approaches have led to questions on toxicity, plant-based sources and microorganisms like bacteria, fungi and algae have been evaluated for synthesizing metal nanoparticles. Gold nanoparticles derived from biological sources are expected to have different properties than those derived from chemical sources, allowing for a wider range of applications. This review provides an overview of the myriad of sources explored for the synthesis of gold nanoparticles which have found useful applications in several fields. The general approach for synthesizing gold nanoparticles is provided followed by the major applications in specific fields namely medicine, biology, electrochemistry and catalysis. Additionally, the possible challenges and future prospects of biosynthesis of nanoparticles have been highlighted. This work could provide an update on the recent advances in the applications of biogenic nanoparticles for future developments.
Salmonella is one of the most common causes of gastroenteritis. In this study, a PCR assay was developed for the rapid detection of microbial cultures of Salmonella enterica sub species of enterica serovar Typhi in samples of patients suspected typhoid. The assay was based on duplicate the STY4669-hypothetical protein gene. The gene primers were designed and blast. Then the bacteria strains were employed for the green synthesis of gold nanoparticles (AuNPs), and one of the strains represented ability to extracellular synthesis of gold nanoparticles. The nanoparticles were characterized using UV–visible spectrophotometer, X-ray powder diffraction, Transmission electron microscopy. The synthesized nanoparticles had a maximum absorption in UV–vis spectra at 556 nm, a crystalline structure, and an average size of 42 nm.
Nanoparticles (NPs) are increasingly used to target bacteria as an alternative to antibiotics. Nanotechnology may be particularly advantageous in treating bacterial infections. Examples include the utilization of NPs in antibacterial coatings for implantable devices and medicinal materials to prevent infection and promote wound healing, in antibiotic delivery systems to treat disease, in bacterial detection systems to generate microbial diagnostics, and in antibacterial vaccines to control bacterial infections. The antibacterial mechanisms of NPs are poorly understood, but the currently accepted mechanisms include oxidative stress induction, metal ion release, and non-oxidative mechanisms. The multiple simultaneous mechanisms of action against microbes would require multiple simultaneous gene mutations in the same bacterial cell for antibacterial resistance to develop; therefore, it is difficult for bacterial cells to become resistant to NPs. In this review, we discuss the antibacterial mechanisms of NPs against bacteria and the factors that are involved. The limitations of current research are also discussed.
A simple and efficient eco-friendly approach for the biosynthesis of stable, monodisperse silver nanoparticles (AgNPs) using Rhododendron dauricum flower extract is described. Different reaction parameters (concentration of plant extract, substrate concentration, pH, temperature and reaction time) were optimized to synthesize AgNPs with controlled properties. AgNPs were characterized in terms of synthesis, size distribution (PDI of 0.25), capping functionalities (phenolic compounds) and microscopic evaluation by UV-Visible spectroscopy, dynamic light scattering, Fourier Transform Infrared (FTIR) spectroscopy and Transmission Electron Microscope (TEM). The specific characteristics and loss of organic content (1.81 mg) of the synthesized nanoparticles was measured by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA). The results showed the simplistic and feasible approach for obtaining stable aqueous monodispersive AgNPs. Further, the antioxidant activity of AgNPs imparted by plant phenolic components was evaluated using DPPH assay and found to be comparable to standard TROLOX.
Silver nanoparticles 1-7 nm in size were synthesized within 2 h in water by challenging an electrochemically active biofilm (EAB) with a solution containing AgNO3 as precursor and sodium acetate as an electron donor. The electrochemically active bacteria present on the anaerobic biofilm act as a catalyst to oxidise the sodium acetate by producing electrons for the reduction of Ag+ ions. The high monodispersity, rapidity, and extracellular nature of this synthesis, together with the production of smaller nanoparticles that are easily separated, make this protocol highly significant in the area of nanoparticle synthesis.
The use of nanotechnology in medicine and more specifically drug delivery is set to spread rapidly. Currently many substances are under investigation for drug delivery and more specifically for cancer therapy. Interestingly pharmaceutical sciences are using nanoparticles to reduce toxicity and side effects of drugs and up to recently did not realize that carrier systems themselves may impose risks to the patient. The kind of hazards that are introduced by using nanoparticles for drug delivery are beyond that posed by conventional hazards imposed by chemicals in classical delivery matrices. For nanoparticles the knowledge on particle toxicity as obtained in inhalation toxicity shows the way how to investigate the potential hazards of nanoparticles. The toxicology of particulate matter differs from toxicology of substances as the composing chemical(s) may or may not be soluble in biological matrices, thus influencing greatly the potential exposure of various internal organs. This may vary from a rather high local exposure in the lungs and a low or neglectable exposure for other organ systems after inhalation. However, absorbed species may also influence the potential toxicity of the inhaled particles. For nanoparticles the situation is different as their size opens the potential for crossing the various biological barriers within the body. From a positive viewpoint, especially the potential to cross the blood brain barrier may open new ways for drug delivery into the brain. In addition, the nanosize also allows for access into the cell and various cellular compartments including the nucleus. A multitude of substances are currently under investigation for the preparation of nanoparticles for drug delivery, varying from biological substances like albumin, gelatine and phospholipids for liposomes, and more substances of a chemical nature like various polymers and solid metal containing nanoparticles. It is obvious that the potential interaction with tissues and cells, and the potential toxicity, greatly depends on the actual composition of the nanoparticle formulation. This paper provides an overview on some of the currently used systems for drug delivery. Besides the potential beneficial use also attention is drawn to the questions how we should proceed with the safety evaluation of the nanoparticle formulations for drug delivery. For such testing the lessons learned from particle toxicity as applied in inhalation toxicology may be of use. Although for pharmaceutical use the current requirements seem to be adequate to detect most of the adverse effects of nanoparticle formulations, it can not be expected that all aspects of nanoparticle toxicology will be detected. So, probably additional more specific testing would be needed.
Biosorption has been shown to be an eco-friendly approach to remove heavy metal ions. In this study, the photosynthetic bacteria Rhodobacter capsulatus was screened and found to have strong ability to adsorb Au(III). The maximum specific uptake of living cells was over 92.43 mg HAuCl(4)/g dry weight of cell in the logarithmic phase. Biosorpion ability would be enhanced by an acidic environment. As the main cations, during biosorption the quantity of Mg(2+) exchanged was more than Na(+). Biosorbed Au(III) could be reduced by carotenoid and enzymes embedded and/or excreted by R. capsulatus, which might be the mechanism of photosynthtic bacteria metal tolerance.
The programmability of Watson-Crick base pairing, combined with a decrease in the cost of synthesis, has made DNA a widely used material for the assembly of molecular structures and dynamic molecular devices. Working in cell-free settings, researchers in DNA nanotechnology have been able to scale up system complexity and quantitatively characterize reaction mechanisms to an extent that is infeasible for engineered gene circuits or other cell-based technologies. However, the most intriguing applications of DNA nanotechnology - applications that best take advantage of the small size, biocompatibility and programmability of DNA-based systems - lie at the interface with biology. Here, we review recent progress in the transition of DNA nanotechnology from the test tube to the cell. We highlight key successes in the development of DNA-based imaging probes, prototypes of smart therapeutics and drug delivery systems, and explore the future challenges and opportunities for cellular DNA nanotechnology.
In the transmission electron microscope, as shown in figure 1 (Nixon 1962), the electron gun at the top illuminates the specimen with the beam angle controlled by the condenser lens. The lenses below the specimen are used to magnify the image of the specimen which is viewed on the final screen at many thousand times magnification. If a second electron gun is placed below the fluorescent screen at the bottom of the column and the electron beam is projected upwards through the same lenses this second electron source will be reduced in size by the same amount that the specimen image is magnified. This effect can be observed with both electron guns on at the same time and demonstrates the reversibility of rays through electron lens systems. In this way the resolved point in the specimen image on the fluorescent screen or on the photographic plate is equal to the focused electron probe in the plane of the specimen.
Gold and silver particles prepared in Laponite suspensions by addition of reductant were studied. The particles obtained were characterized by ultraviolet-vis spectrophotometry and transmission electron microscopy. It was observed that the bimetallic gold/silver particles were alloy particles rather than core-shell particles. The Laponite does not operate as a hard template for the preparation of the particles. Instead Laponite acts a protective colloid to obtain nanometallic particles.
Aqueous gold sols with a mean diameter of 16 nm have been transferred into various mixtures of organic solvents with different refractive indices using a polymeric comb stabilizer to prevent colloid coagulation. The sols change color from red to purple depending on the refractive index of the solvent. The optical properties of the sols in the different media are in excellent agreement with the predictions of Mie theory.
Gold nanoparticles have been used as a probe for the detection of various aminoglycosidic antibiotics like streptomycin, gentamycin and neomycin. The nature of interaction between these drugs and gold nanoparticles has been probed by various analytical techniques like UV–vis, FT-IR, TEM, etc. Such studies can be used for the determination of drugs in drug formulations. Further in vitro antibacterial activities of drugs capped Au nanoparticles (Au@drugs) were investigated against various strains of Gram positive and Gram negative organisms viz. Staphylococcus aureus, Micrococcus luteus, E. Coli and Pseudomonas aeruginosa. Our results suggest that gold nanoparticles could act as an effective drug carrier in drug delivery system.
In recent years, the development of efficient green chemistry methods for synthesis of metal nanoparticles has become a major focus of researchers. They have investigated in order to find an eco-friendly technique for production of well-characterized nanoparticles. One of the most considered methods is production of metal nanoparticles using organisms. Among these organisms plants seem to be the best candidates and they are suitable for large-scale biosynthesis of nanoparticles. Nanoparticles produced by plants are more stable and the rate of synthesis is faster than in the case of microorganisms. Moreover, the nanoparticles are more various in shape and size in comparison with those produced by other organisms. The advantages of using plant and plant-derived materials for biosynthesis of metal nanoparticles have interested researchers to investigate mechanisms of metal ions uptake and bioreduction by plants, and to understand the
possible mechanism of metal nanoparticle formation in plants. In this review, most of the plants used in metal nanoparticle synthesis are shown.
In this work, in vitro biosynthesis of silver nanoparticles was achieved using AgNO(3) as a substrate by Penicillium fellutanum isolated from coastal mangrove sediment. The biosynthesis was faster within minutes of silver ion coming in contact with the cell filtrate. Presence of silver nanoparticles in the culture filtrate was confirmed by absorption peak at 430 nm, as well under transmission electron microscope. The biosynthesis of nanoparticles was the maximum when the culture filtrate was treated with 1.0 mM AgNO(3), maintained at 0.3% NaCl and pH 6.0, incubated at 5 degrees C for 24h. The culture filtrate, precipitated with ammonium sulphate, was proved to have a single protein band with a molecular weight of 70 kDa using polyacrylamide gel electrophoresis. The present work highlighted the possibility of using the marine fungal strain of P. fellutanum to achieve a fast rate of nanoparticles synthesis.
The genus Citrobacter is a distinct group of human pathogens comprising three species: Citrobacter freundii (biotypes a and b), Citrobacter amalonaticus, and Citrobacter diversus. In this review the clinical and microbiologic experience during 1972–1978 at the Seattle Veterans Administration Medical
Center (Seattle, Wash.) with 298 isolates of Citrobacter is analyzed in relation to a survey of the literature. The most common sources of citrobacter isolates were urine, sputum,
and soft tissue exudates. Members of this genus can cause neonatal meningitis and, perhaps, gastroenteritis in both children
and adults. Although deep tissue infections due to Citrobacter have been reported only occasionally, in this study a large number of cultures of peritoneal fluid and bone contained Citrobacter. Most isolates of Citrobacter were from elderly, debilitated patients and either represented secondary infections or were of indeterminate clinical significance.
Efficient conversion of strongly absorbed light by plasmonic gold nanoparticles to heat energy and their easy bioconjugation suggest their use as selective photothermal agents in molecular cancer cell targeting. Two oral squamous carcinoma cell lines (HSC 313 and HOC 3 Clone 8) and one benign epithelial cell line (HaCaT) were incubated with anti-epithelial growth factor receptor (EGFR) antibody conjugated gold nanoparticles and then exposed to continuous visible argon ion laser at 514nm. It is found that the malignant cells require less than half the laser energy to be killed than the benign cells after incubation with anti-EGFR antibody conjugated Au nanoparticles. No photothermal destruction is observed for all types of cells in the absence of nanoparticles at four times energy required to kill the malignant cells with anti-EGFR/Au conjugates bonded. Au nanoparticles thus offer a novel class of selective photothermal agents using a CW laser at low powers. The potential of using this selective technique in molecularly targeted photothermal therapy in vivo is discussed.
The dependence of the optical properties of spherical gold nanoparticles on particle size and wavelength were analyzed theoretically using multipole scattering theory, where the complex refractive index of gold was corrected for the effect of a reduced mean free path of the conduction electrons in small particles. To compare these theoretical results to experimental data, gold nanoparticles in the size range of 5 to 100 nm were synthesized and characterized with TEM and UV-vis. Excellent agreement was found between theory and experiment. It is shown that the data produced here can be used to determine both size and concentration of gold nanoparticles directly from UV-vis spectra. Equations for this purpose are derived, and the precision of various methods is discussed. The major aim of this work is to provide a simple and fast method to determine size and concentration of nanoparticles.
Infection and antimicrobial resistance are important issues in severe burn. The aims of this prospective study were to investigate the profile of microorganisms and resistance to antimicrobial agents in a tertiary referral burn centre; 113 people aged >10 years, with partial- or full-thickness burns, were included in the study. A total of 733 samples including 275 swabs, 164 tissue biopsies, 258 urine samples, 26 blood samples and 10 sputum samples were collected, from which 124 microorganisms were isolated. Pseudomonas aeruginosa and Citrobacter spp were the most prevalent isolates (57.3% and 35.5%, respectively); 95.5% of Citrobacter. isolates were Citrobacter freundii. Antibiogram results obtained from 15 antimicrobial agents demonstrated that imipenem was the most effective agent against P. aeruginosa, followed by ciprofloxacin and piperacillin/tazobactam (67.9%, 43% and 37.5% sensitive, respectively). At least 60% of all Citrobacter isolates were sensitive to various antimicrobial agents, the highest sensitivity being obtained by ceftazidime and cefepime (81.6% and 78.4%, respectively). Sensitivity of P. aeruginosa isolates to the agents of each antimicrobial class was significantly different (p<0.001). The incidence of C. freundii and the resistance of P. aeruginosa to anti-pseudomonas agents were exceptionally high.
A major aim of medicine has long been the early and accurate diagnosis of clinical conditions, providing an efficient treatment without secondary effects. With the emergence of nanotechnology, the achievement of this goal seems closer than ever. To this end, the development of novel materials and devices operating at the nanoscale range, such as nanoparticles, provides new and powerful tools for imaging, diagnosis and therapy. This review focuses on the significant improvements in performance that nanoparticles offer compared with existing technologies relevant to medicine. Specifically, we address the design of multifunctional nanoparticles as an alternative system for drug and gene delivery, which has great potential for therapy in areas, such as cancer and neuropathologies. Moreover, we discuss the controversy generated by the possible toxic health effects of nanoparticles.
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