Saturday, December 24, 2011

fungi in the synthesis of nanoparticle

The use of fungi in the synthesis of nanoparticle is a relatively recent addition to the list of microorganisms. The shift from bacteria to fungi as a means of developing natural “nanofactories” has the added advantage that downstream processing and handling of the biomass would be much simpler. The use of eukaryotes is potentially exiting since they secrete large amount of proteins, thus increasing productivity, and their easy usage in laboratory works is a suitable option in production of metallic nanoparticles among other microorganisms. More over the process can be easily scaled up, economically viable with the possibility of easily covering large surface areas by suitable growth of mycelia. Therefore, the present study has reported the biological process for the synthesis of silver nanoparticles extracellularly using R.stolonifer.
Rhizopus stolonifer showed maximum absorbance at 422nm. Parametric optimization study showed maximum absorbance at 40C and pH 7.0. Further characterization was made by UV-Visible
absorption spectroscopy which shows maximum absorption at 422 nm, Transmission Electron Microscope (TEM) revealed the formation of spherical nanoparticles with size ranging between 5 to 50 nm. Energy Dispersive Spectroscope (EDS) shows the optical absorption peak at 3kev, Fourier Transform Infrared (FT-IR) shows the bands at 1645(1), 1537(2) and 1454(3) cm-1. The biosynthesized silver nanoparticles have broad range of applications such as fluorescent biological labels, drug and gene delivery, bio detection of pathogens, detection of proteins, probing of DNA structure, tissue engineering, tumor destruction via heating, separation and purification of biological molecules and cells, and phagokinetic studies. Majority of the silver nanoparticle applications in medicine are geared towards drug delivery. Therefore, further work will be on antibacterial activity of silver nanoparticles.
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Bioelectronic DNA detection involves forming an electronic circuit mediated by nucleic acid hybridization and it serves as the basis for a DNA detection system called eSensor™ [1-4]. This system uses low-density DNA chips containing electrodes coated with DNA capture probes. Target DNA present in the sample hybridizes specifically both to capture probes and ferrocene labeled signal probes in solution thereby generating an electric current. Currente Sensor DNA chips contain as many as 36 electrodes for simultaneous detection of multiple pathogens from a single sample.

Many pathogens cause both acute and chronic disease at relatively low copy number and may be difficult or impossible to propagate in culture. Thus, most pathogen detection systems rely on nucleic acid amplification by using polymerase chain reaction (PCR). One highly effective amplification strategy targets conserved sequences among the family of organisms of interest. Such broad-range PCR strategies have been used to identify and characterize several known and previously uncharacterized bacteria [5,6] and viruses [7,8]. In order to maximize the utility of these effective pathogen nucleic acid amplification systems, amplification needs to be coupled with rapid, sensitive, and specific detection. Bioelectronic DNA detection by use of the eSensor chip might fulfill this need.

Human papillomaviruses (HPV) serve as an ideal model system for determining the efficiency and feasibility of eSensor DNA detection technology since there are at least 30 distinct genital HPV types that can be effectively amplified with broad-range consensus PCR primers. We designed two eSensor chips, each containing 14 probes specific for the conserved L1 region of the HPV genome. We evaluated clinical cervical cytology samples known to contain one or more HPV types. The eSensor DNA detection platform successfully detected the correct HPV type in most of these clinical samples, demonstrating that the system provides a rapid, sensitive, specific, and economical approach for multiple-pathogen detection and identification from a single sample.Background We used human papillomaviruses (HPV) as a model system to evaluate the utility of a nucleic acid, hybridization-based bioelectronic DNA detection platform (eSensor) in identifying multiple pathogens.