A fluorescent nanoprobe for single bacterium tracking: functionalization of silver nanoparticles with tryptophan to probe the nanoparticle accumulation with single cell resolution

The investigation of the interaction of silver nanoparticles and live bacteria cells is of particular importance for understanding and controlling their bactericidal properties. In this study, the process of internalization of silver nanoparticles in Escherichia coli cells was followed by means of synchrotron excitation deep ultraviolet (DUV) fluorescence imaging. Antimicrobial nanostructures that can absorb and emit light in the UV region were prepared by functionalization of silver nanoparticles with tryptophan amino acid and used as environmentally sensitive fluorescent probes. The nanostructures were characterized by morphological (TEM) and spectroscopic methods (UV-vis, FTIR, XPS, and photoluminescence). The TEM images and the analyses of the UV-vis spectra suggested that the addition of tryptophan led to the formation of hybrid nanostructures with pronounced eccentricity and larger sizes with respect to that of the initial silver nanoparticles. The DUV imaging showed that it was possible to distinguish the fluorescent signal pertaining to silver-tryptophan nanostructures from the autofluorescence of the bacteria. The spatial resolution of the fluorescence images was 154 nm which was sufficient to perform analyses of the accumulation of the nanostructures within a single bacterium. The DUV imaging results imply that the tryptophan-functionalized silver nanoparticles interact with cell membranes via insertion of the amino acid into the phospholipid bilayer and enter the cells

Drying of biological materials in a spout-fluid bed with a draft tube

The possibility of applying a spout-fluid bed with a draft tube and conical bottom was investigated for drying fluid media with a certain content of suspended material was investigated. The major goal who to study the drying of biological materials and products of food the industry. Experimental results concerning the fluidmechanical characteristics of a spout-fluid bed with a centrally situated draft tube and the drying characteristics were obtained on a pilot scale unit, 0.250 m in diameter, with a toed consisting of polyethylene particles 3.6 mm mean diameter and 940 kg/m3 density. Within the regime of the fluid mechanical stability, the system could be used for drying biological suspensions with satisfactory results

Processing and properties of scaffolds based on calcium phosphate doped with magnesium, copper and zinc-ions coated with gelatin

The main goal of this study was to examine the possibility for obtaining macroporous scaffolds with defined properties based on calcium phosphate doped with magnesium, copper and zinc ions, coated with gelatin, which would potentially provide controlled conditions for the formation of new bone tissue after implantation. As a first, multi-doped nanoparticles of hydroxyapatite (HAp), which represents the main component of the inorganic part of bone tissue, was synthesized by autoclaving the precursor solution obtained at a Ca/P molar ratio of 1.52. Calcium in the initial solution was partially replaced by ions of magnesium (5 mol.%), copper (0.4 mol.%) and zinc (0.4 mol.%). Obtained powder was further calcinated, the changes in the morphology of the powders during calcination at 1000 ̊ C were reflected in the transition of spherically agglomerated needle-like nanoparticles of the multi-doped hydroxy-apatite powder to a spherical grained morphology. Macroporous bioceramic structures were obtained using the sponge replica method, green macroporous samples made of calcinated multi-doped powder, polyvinyl alcohol and water were sintered at 1.370°Ϲ and 1.430°Ϲ. X-ray diffraction analysis deter-mined that the presence of magnesium in the structure of hydroxyapatite favors the phase transformation of HAp into b-tricalcium-phosphate (b-TCP), which contributed to the formation of the biphasic HAp/b-TCP system during the calcination of the powders, but also during the sintering of macroporous beads. Examination of the antimicrobial activity of the obtained macroporous supports against E. coli showed a more effective degree of inhibition compared to S. aureus. A significant increase in the compressive strength of sintered macroporous scaffolds was obtained after the formation of coating based on 7.5% gelatin solution

The production of cellulase from the waste tobacco residues remaining after polyphenols and nicotine extraction and bacterial pre-treatment

Agricultural by-products are generated in large amounts in various industries, creating a serious disposal problem. Valorisation of tobacco waste for the extraction of value-added compounds and the production of enzymes could reduce both the problems of its disposal and the costs of cellulase production. Hitherto, there have been no reported studies concerning the utilization of tobacco residues (after extraction of polyphenols and nicotine, and fermentation pre-treatment by Streptomyces fulvissimus CKS7) for the production of cellulase (CMCase and.vicelase) by Paenibacillus chitinolyticus CKS1. The optimal conditions for the polyphenols and nicotine extraction process were obtained using the response surface methodology: 60 s extraction time in water and 30 mL g(-1) liquid/solid ratio. After the applied bacterial fermentation as a pre-treatment of tobacco residues, using Paenibacillus species, the extraction of polyphenols decreased by up to 10 %, while the extraction of nicotine increased by up to 35 %. Afterward, the maximum of cellulase activities (CMCase of 0.878 U g(-1) and avicelase of 1.417 U g(-1)) were achieved using of the strain CKS1

Fabrication and antibacterial properties of ZnO-alginate nanocomposites

Alginate was used as a controlled environment for the growth of ZnO nanoparticles. The formation of nanostructured particles was confirmed by a blue shift in the onset of the optical absorption with respect to bulk ZnO. From the XRD measurements it was found that the obtained ZnO nanoparticles have a hexagonal crystal structure. The emission spectrum of the nanocomposite is dominated by a strong band-to-band recombination, while the emission from the ZnO defect states depended on the preparation conditions. Besides showing the presence of Zn 2p, O is, Na 1s and C 1s core levels, the XPS analysis also showed that the O is spectra can be resolved into two lines that are attributed to the presence of OH groups on the surface of the particles and ZnO, respectively. Antimicrobial tests revealed that the ZnO-alginate nanocomposite exhibits a strong activity against the common pathogens Staphylococcus aureus and Escherichia coli. (C) 2011 Elsevier Ltd. All rights reserved

Silver nanoparticles encapsulated in glycogen biopolymer Morphology, optical and antimicrobial properties

The glycogen biopolymer from the bovine liver has been used as stabilization agent for the growth of silver nanoparticles The samples with various contents of silver were prepared by two different procedures that include fast (using microwave radiation) and slow (conventional) heating of the reaction mixtures The TEM images of the two nanocomposites showed the presence of nanoparticles with average diameter of 9 7 and 10 4 nm respectively The results also revealed that the optical properties of the obtained nanocomposite samples strongly depend on the method of preparation The samples prepared using microwave radiation exhibited narrower surface plasmon resonance peaks while the silver nanoparticles induced quenching of the photoluminescence of glycogen in all of the tested samples Antimicrobial activity tests were carried out against Staphylococcus aureus Escherichia coli and Candida albicans pathogens and showed that the microbial growth was gradually reduced as the concentration of the silver increased Also after 2 h of exposure to the nanocomposites the number of cells was significantly reduced ( GT 99%) for all the strains tested (C) 2010 Elsevier Ltd All rights reserve

Structure and optical properties of noble metal and oxide nanoparticles dispersed in various polysaccharide biopolymers

We present the results on the structure and the optical properties of noble metal (Ag, Au) and oxide (ZnO) nanoparticles synthesized by various methods in different polysaccharide matrices such as chitosan, glycogen, alginate and starch. The structure of the obtained nanoparticles was studied in detail with microscopic techniques (TEM, SEM), while the XPS spectroscopy was used to investigate the effects at the nanoparticle-biomolecule interfaces. The antimicrobial activity of the nanocomposite films with Ag nanoparticles was tested against the Staphylococcus aureus, Escherichia coli and Candida albicans pathogens. In addition, we will present the results on the structure and optical properties of the tryptophan amino acid functionalized silver nanoparticles dispersed in water soluble polymer matrices.Proceedings of SPIE, Conference on Physical Chemistry of Interfaces and Nanomaterials X, Aug 21-23, 2011, San Diego, C

Influence of spray drying technique on survival of Bradyrhizobium onto sodium alginate based carriers

Application of microbial inoculants to the soil can improve the nutrient uptake by plants and increase the productivity of the crops. Inoculants should ensure a suitable microenvironment and long survival of bacteria in biological fertilizer and after application to seeds. The immobilization of rhizobia onto a carrier can involve the covering and protecting of the microorganisms. Spray drying is a relatively new immobilization technique for the immobilization of microorganisms onto a carrier and it is rarely used for rhizobia. The survival of bacteria during spray drying immobilization onto alginate based carriers was just 8.1 and 6.8% for Bradyrhizobium spp. strains 542 and 526. The working temperature during drying process was high (outlet 50°C) and it presents more than temperature limit for rhizobia survival. Accordingly, the obtained results were justifiably low in value. The presence of sucrose in liquid inoculant had a positive influence on the survival of rhizobia during immobilization

Effective valorisation of barley bran for simultaneous cellulase and beta-amylase production by Paenibacillus chitinolyticus CKS1: Statistical optimization and enzymes application

The agricultural raw industry generates large amounts of annually by-products that create disposal problems. Hitherto, there have been no reported papers about the simultaneous production of cellulase and beta-amylase from these raw materials using Paenibacillus sp. that would reduce the costs. Thus, in this paper simultaneous cellulase (CMC-ase and avicelase) and beta-amylase production using barley bran and the application of the natural isolate Paenibacillus chitinolyticus CKS1 and potential enzymes in the hydrolysis process was studied. Response surface methodology was used to obtain the maximum enzyme activity (CMC-ase 0.405 U mL(-1), avicelase 0.433 U mL(-1) and beta-amylase 1.594U mL(-1)). Scanning electron microscopy showed degradation of the lignocellulosic-starch structure of barley bran after fermentation. The CKS1 bacterial supernatant, which contains cellulases and beta-amylase, could hydrolyze cotton fibres and barley bran, respectively. The main products after enzymatic hydrolysis of cotton fibres and barley bran, glucose (0.117 (-1)(g gmat)) and maltose (0.347 (-1)(g gmat)), were quantified by high performance liquid chromatography (HPLC). The produced enzymes could be used for hydrolysis of cotton fabric and barley bran to glucose and maltose, respectively. Application of simultaneous enzymes production using an agricultural by-product is economically and environmentally accepted and moreover, valuable biotechnological products, such as glucose and maltose, were obtained in this investigation

Viscoelastic properties and antimicrobial activity of cellulose fiber sheets impregnated with Ag nanoparticles

A silver nanoparticle colloid was prepared by a modified Tollens method using D-glucose as the reduction agent. The obtained nanoparticles were used for the modification of pine, linter and recycled cellulose fibers. Although the silver contents were relatively low (0.05-0.13 wt.%), the cellulose-sheets prepared from the modified fibers show improved mechanical and viscoelastic properties. The tensile index (strength) increased with up to 30% in comparison to the index of the sheets obtained from the untreated fibers. The influence of the nanoparticles on the viscoelastic properties of the cellulose sheets was investigated by dynamic mechanical analysis (DMA) in the temperature range from -120 to 20 degrees C and with a force frequency of 100Hz. A broad relaxation transition positioned at -80 degrees C was observed in the loss modulus spectrum of all the cellulose sheets, while the Ag-modified sheets exhibited higher storage moduli values in the whole temperature range. The antimicrobial activity tests show that the pine, silver and recycled cellulose fiber sheets with silver nanoparticles can be successfully employed to prevent the viability and growth of the common pathogens Staphylococcus aureus, Escherichia coli and Candida albicans. (C) 2012 Elsevier Ltd. All rights reserved