Fototermičke bioanalitičke metode za testiranje toksičnosti pesticida

This paper describes bioanalytical methods and biosensors which rely on cholinesterase (ChE) inhibition and can be used to detect and test the toxicity of organophosphate (OP) and carbamate pesticides. Particular attention is given to the combined use of these methods and photothermal detection that has recently led to improved sensitivity and increased sample throughput of ChE bioanalytical assay. Following a rapid and simple sample preparation procedure, this assay can detect organophosphate pesticides such as paraoxon in the sub ng/mL concentration range. The AChE bioanalytical method demonstrated different sensitivity to various pesticides, which correlated well with pesticide toxicity expressed as LD50 for rats. Similarly, the same pesticide yielded different ChE inhibition in different organisms. This opens the possibility of applying these bioanalytical methods to evaluate the acute toxicity of OP compounds or of environmental samples to particular organisms.U ovom se radu razrađuje koncepcija bioanalitičkih metoda i biosenzora na primjeru inhibicije kolinesteraza. Ovi bi se postupci mogli primijeniti za testiranje toksičnosti organofosfornih i karbamatnih pesticida. Kombiniranom primjenom ove koncepcije i fototermalne detekcije postiglo se povećanje osjetljivosti detekcije i broja analiziranih uzoraka. Autori su analizirali uzorke povrća na prisutnost organofosfornih spojeva paraoksona, diazinona i klorpirifosa te monometilnih karbamata karbarila i karbofurana. Autori su utvrdili da i nakon primijenjene jednostavne i brze pripreme mogu detektirati koncentracije npr. paraoksona ispod 1 ng/ml. Pokazalo se da je detekcija pesticida u povrću (luk, salata) s pomoću fototermalnog biosenzora moguća i bez ekstrakcijskih i prekoncentracijskih postupaka, što znatno ubrzava i olakšava analize. Bioanalitička metoda s acetilkolinesterazom pokazala je različitu osjetljivost prema pojedinim pesticidima i to je bilo u skladu s poznatim podacima o akutnoj toksičnosti izra.enoj oralnim LD50 vrijednostima za štakore. Stoga autori smatraju da bi primjena ove metode mogla nadopuniti ili nadomjestiti upotrebu laboratorijskih .ivotinja u testiranju toksičnosti antikolinesteraznih pesticida. Autori su također utvrdili različitosti u interakciji istog insekticida i acetilkolinesteraze različitih organizama

Novel laser-based photothermal methods of chemical analysis

University of Nova Gorica (UNG) provides access to knowledge, high quality education and incorporates nine different main research areas. One of them is covered by the Laboratory for Environmental Research which conducts basic and applied research in different areas of environmental sciences such as the investigation of photochemical and microbial degradation, and transport of pollutants in the environment; the development of laser-based methods, bioanalytical methods, and ecotoxicological tests for the identification and determination of toxic compounds and their effects on the environment; the development of new materials for applications in environmentally friendly technologies as well as the research in molecular biology and neurobiology. All in all, the main stream of our scientific work in TRANS2CARE project will be related to novel laser-based photothermal methods of chemical analysis coupled to bioanalytical assays and flow injection analysis

Chitosan-cellulose Composite Materials: Preparation, Characterization and Application for Removal of Microcystin

We developed a simple and one-step method to prepare biocompatible composites from cellulose (CEL) and chitosan (CS). [BMIm+Cl−], an ionic liquid (IL), was used as a green solvent to dissolve and prepare the [CEL + CS] composites. Since majority (\u3e88%) of IL used was recovered for reuse by distilling the aqueous washings of [CEL + CS], the method is recyclable. XRD, FTIR, NIR, 13C CP-MAS-NMR and SEM were used to monitor the dissolution and to characterize the composites. The composite was found to have combined advantages of their components: superior mechanical strength (from CEL) and excellent adsorption capability for microcystin-LR, a deadly toxin produced by cyanobacteria (from CS). Specifically, the mechanical strength of the composites increased with CEL loading; e.g., up to 5× increase in tensile strength was achieved by adding 80% of CEL into CS. Kinetic results of adsorption confirm that unique properties of CS remain intact in the composite, i.e., it is not only a very good adsorbent for microcystin but also is better than all other available adsorbents. For example, it can adsorb 4× times more microcystin than the best reported adsorbent. Importantly, the microcystin adsorbed can be quantitatively desorbed to enable the composite to be reused with similar adsorption efficiency

Synthesis, Structure and Antimicrobial Property of Green Composites from Cellulose, Wool, Hair and Chicken Feather

Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simple one-step process in which butylmethylimidazolium chloride (BMIm+Cl−), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl−] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of [CEL + KER] composites made from all three different sources, wool, hair and chicken feathers i.e., [CEL + wool], [CEL + hair] and [CEL + feather]. Since mechanical strength is due to CEL, and CEL has only random structure, [CEL + feather] has, expectedly, the strongest mechanical property because feather has the lowest content of α-helix. Conversely, [CEL + wool] composite has the weakest mechanical strength because wool has the highest α-helix content. All three composites exhibit antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA). The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the keratin, namely, the bactericidal effect is strongest for feather and weakest for wool. These results together with our previous finding that [CEL + KER] composites can control release of drug such as ciprofloxacin clearly indicate that these composites can potentially be used as wound dressing

One-Pot Synthesis of Biocompatible Silver Nanoparticle Composites from Cellulose and Keratin: Characterization and Antimicrobial Activity

A novel, simple method was developed to synthesize biocompatible composites containing 50% cellulose (CEL) and 50% keratin (KER) and silver in the form of either ionic (Ag+) or Ag0 nanoparticles (Ag+NPs or Ag0NPs). In this method, butylmethylimmidazolium chloride ([BMIm+Cl–]), a simple ionic liquid, was used as the sole solvent and silver chloride was added to the [BMIm+Cl–] solution of [CEL+KER] during the dissolution process. The silver in the composites can be maintained as ionic silver (Ag+) or completely converted to metallic silver (Ag0) by reducing it with NaBH4. The results of spectroscopy [Fourier transform infrared and X-ray diffraction (XRD)] and imaging [scanning electron microscopy (SEM)] measurements confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. Powder XRD and SEM results show that the silver in the [CEL+KER+Ag+] and [CEL+KER+Ag0] composites is homogeneously distributed throughout the composites in either Ag+ (in the form of AgClNPs) or Ag0NPs form with sizes of 27 ± 2 or 9 ± 1 nm, respectively. Both composites were found to exhibit excellent antibacterial activity against many bacteria including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, methicillin-resistant S. aureus (MRSA), and vancomycin-resistant Enterococus faecalis (VRE). The antibacterial activity of both composites increases with the Ag+ or Ag0 content in the composites. More importantly, for the same bacteria and the same silver content, the [CEL+KER+AgClNPs] composite is relatively more toxic than [CEL+KER+Ag0NPs] composite. Experimental results confirm that there was hardly any Ag0NPs release from the [CEL+KER+Ag0NPs] composite, and hence its antimicrobial activity and biocompatibility is due not to any released Ag0NPs but rather entirely to the Ag0NPs embedded in the composite. Both AgClNPs and Ag0NPs were found to be toxic to human fibroblasts at higher concentration (\u3e0.72 mmol), and for the same silver content, the [CEL+KER+AgClNPs] composite is relatively more toxic than the [CEL+KER+Ag0NPs] composite. As expected, by lowering the Ag0NPs concentration to 0.48 mmol or less, the [CEL+KER+Ag0NPs] composite can be made biocompatible while still retaining its antimicrobial activity against bacteria such as E. coli, S. aureus, P. aeruginosa, MRSA, and VRE. These results, together with our previous finding that [CEL+KER] composites can be used for the controlled delivery of drugs such as ciprofloxacin, clearly indicate that the [CEL+KER+Ag0NPs] composite possesses all of the required properties for it to be successfully used as a high-performance dressing to treat chronic ulcerous infected wounds

Bilirubin is an Endogenous Antioxidant in Human Vascular Endothelial Cells

Bilirubin is a standard serum biomarker of liver function. Inexplicably, it is inversely correlated with cardiovascular disease risk. Given the role of endothelial dysfunction in originating cardiovascular diseases, direct analysis of bilirubin in the vascular endothelium would shed light on these relationships. Hence, we used high-performance liquid chromatography coupled with thermal lens spectrometric detection and diode array detection for the determination of endogenous cellular IX\u3b1-bilirubin. To confirm the isomer IX\u3b1-bilirubin, we used ultra-performance liquid chromatography coupled with a high-resolution mass spectrometer using an electrospray ionization source, as well as tandem mass spectrometric detection. We measured bilirubin in both arterial and venous rat endothelium (0.9\u20131.5 pmol mg 121 protein). In the human endothelial Ea.hy926 cell line, we demonstrated that intracellular bilirubin (3\u20135\u2009pmol mg 121 protein) could be modulated by either extracellular bilirubin uptake, or by up-regulation of heme oxygenase-1, a cellular enzyme related to endogenous bilirubin synthesis. Moreover, we determined intracellular antioxidant activity by bilirubin, with EC50\u2009=\u200911.4\u2009\ub1\u20090.2\u2009nM, in the range of reported values of free serum bilirubin (8.5\u201313.1\u2009nM). Biliverdin showed similar antioxidant properties as bilirubin. We infer from these observations that intra-endothelial bilirubin oscillates, and may thus be a dynamic factor of the endothelial function

Optimisation of FIA system for detection of organophosphorus and carbamate pesticides based on cholinesterase inhibition

Abstract The sensitivity of the bioanalytical FIA system containing different immobilised cholinesterases (AChEs from electric eel, human erythrocytes, bovine erythrocytes and BuChE from horse serum) for determination of organophosphorus and carbamate pesticides was tested. Responses to some frequently used organophosphorus (paraoxon, oxydemeton-methyl, triazophos) and carbamate (carbofuran, propoxur) pesticides were found to be dependent on the origin of cholinesterases. The highest sensitivity was obtained by bioanalytical columns prepared with electric eel AChE while the lowest sensitivity was shown by the bioanalytical columns prepared with horse serum BuChE. The differences in responses for different enzymes were found to be less pronounced when the contact time between the enzyme and the pesticide is long enough (low flow rates). The optimal flow rate was chosen as a compromise between the duration of analysis and reasonably low limits of detection

Photochemical degradation of digoxin tested by Na,K-ATPase activity

The photochemical degradation of digoxin aqueous solution was obtained by Xelamp irradiation. The concentrations of digoxin in irradiated solutions were detected by measurements of Na,K-ATPase activity and by HPLC analysis. The excellent agreement using two independent methods for determination of digoxin concentration in the irradiated samples was achieved.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Projects for Ferme Ornée on the Island of Lokrum by Archduke Ferdinand Maximilian of Habsburg

This research deals with projects for a residence on the island of Lokrum by Archduke Maximilian I of Habsburg (1832-1867). In the short period of owning the island (1859-1867), Maximilian ordered three different designs for Lokrum. The subject of research in this paper is the first phase of the project, dating from 1860 to 1866, when the general plan of the island, Maximilian’s residence, farm building and court chapel were designed. The research is based on an analysis of primary archival sources while the contemporary models for the project have been found through literature review. Twenty archival drafts have been described textually and graphically published. Maximilian actively participated in the planning and design process, but the author of the projects was Thomas Friedrich. After the general plan of the island from 1860 came sixteen preserved plans of Maximilian’s residence, which are with this research dated to the period from 1862 to 1864. The drafts for the farm building, court chapel and altar date back to the period from 1864 to 1866. Although in terms of architecture it was only partially built (only the landscape part of the project was executed), the Lokrum project from 1860 to 1866 shows Maximilian’s original idea of the island before the later grandiose plans of transformation into an imperial residence