Heavy metals concentration in soils from parks and green areas in Belgrade

The current study included the investigation of several metals and their distribution in urban soils from parks and green areas in the city of Belgrade. The soils were sampled in January and February 2008. The concentrations of Cd, Co, Cu, Pb, Mn and Zn were measured, as well as the pH values and organic matter contents. The obtained results showed that there was a significant level of contamination in some samples, especially with lead, and that it was most probably caused by anthropogenic activities, mostly from traffic. The results were compared with the National legislation and Netherlands standards. Also, the recent results were compared with the data from previous work and it was concluded that there has been a certain increase of the Pb concentration in the past three years. The level of pollution in playground soil was very high and each analyzed sample exceeded the Dutch target value for Cd, Co and Pb

Antimicrobial activity of copper-polyaniline nanocomposite

By combining copper nanoparticles (CuNPs) as a good antimicrobial agent with polyaniline (PANI), which also shows some degree of antimicrobial activity, we were able to synthesize a novel promising antimicrobial material – copper-polyaniline (Cu-PANI) nanocomposite. It was prepared by simple in situ polymerization method, when thepolymer and metal nanoparticles (dav= 6 nm)are produced simultaneously.Quantitative (antimicrobial assay) and qualitative (atomic force microscopy – AFM) analyses showed that synergestic effect of CuNPs and PANI against bacteriaE. coli andS. aureus,and fungusC. albicans, provides its faster andhigher antimicrobial activity than any component acting alone.This makes it a great candidate for fast waste water treatment.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 201

Swelling, Mechanical and Antimicrobial Studies of Ag/P(HEMA/IA)/PVP Semi-IPN Hybrid Hydrogels

A simple and fast approach to the design and production of new hybrid polymeric biomaterials with silver particles is presented in this work. Silver/semi-interpenetrating network hybrid hydrogels (Ag/semi-IPNHHs) were prepared through an optimized solution crosslinking copolymerization of 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA), in the presence of PVP, a silver salt and a reducing green agent (Ag/P(HEMA/IA)/PVP). PVP was chosen due to its protective, reduction, and nucleation properties in the production of metal particles. The structure of the Ag/semi-IPNHH was characterized by Fourier transform infrared spectroscopy (FTIR). The presence of silver and PVP in the network was confirmed by FTIR spectra. The results obtained by dynamic mechanical analysis (DMA) showed good mechanical properties for all samples. The swelling studies of Ag/P(HEMA/IA)/PVP were conducted in the temperature range of 25-55 degrees C, in the buffer of pH 7.40. The Ag/semi-IPNHH showed temperature-sensitive swelling properties, with the lower critical solution temperature (LCST) values in the physiologically interesting interval. The antimicrobial activity of the samples was tested using E. coli, S. aureus and C. albicans pathogens. It was concluded that the antimicrobial potential depends on the hydrogels composition and the type of microbes12th Annual YUCOMAT Conference, Sep 06-10, 2010, Herceg Novi, Montenegr

Antibacterial activity of copper nanoparticles

Copper nanoparticles (CuNPs), with an average particle size of about 5 nm, was prepared by the simple chemical reduction procedure. TEM and UV– Vis spectroscopy contributed to the analysis of size and optical properties of CuNPs, and their antibacterial activity was evaluated toward human pathogenic bacteria Escherichia coli and Staphylococcus aureus, in a concentration dependent manner. The changes in the cell membrane morphology of tested strains were investigated by atomic force microscope (AFM), after 2 h of their contact with CuNPs. It was found that CuNPs cause different types of cell membrane disruptions, as well as that S. aureus bacteria were slightly resistant to the cell membrane damage than E. coli

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

Size‐dependent antibacterial properties of Ag nanoparticles supported by amino‐functionalized poly(GMA‐ co ‐EGDMA) polymer

Size-dependent antimicrobial ability of silver nanoparticles (Ag NPs) supported by amino-functionalized poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EGDMA)) macroporous copolymer was tested against Gram-negative bacteria Escherichia coli. Inorganic/organic hybrids with distinctly different average sizes of Ag NPs (6.6 and 12.1 nm) were prepared by functionalization of poly(GMA-co-EGDMA) with either 1,8-diaminooctane or ammonia, and consequent reduction of silver ions with amino groups. The transmission electron microscopy (TEM), infrared and UV–Vis reflection spectroscopy, elemental analysis, and inductively coupled plasma atomic emission measurements were used to characterize synthesized hybrid materials. Time- and concentration-dependent antimicrobial performances of prepared samples revealed higher reduction rates of E. coli when hybrid with smaller in size Ag NPs was used. The difference between rates of reduction of E. coli for different size Ag NPs is becoming more pronounced by decrease of the concentration of silver. POLYM. COMPOS., 2018. © 2018 Society of Plastics Engineers. © 2018 Society of Plastics Engineer

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

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