Controlled release of ranitidine from conductive polypyrrole films

Incorporation and controlled release of active substances from the conductive polypyrrole films by electric stimulation were investigated. Change of the redox state of the conductive polymer was induced by this stimulation, which allowed the incorporation and release of the drug at different rates. Polymerization of pyrrol on a stainless steel substrate was performed by cycling the potential 40 times in predetermined potential window, after which uniform polymeric film was formed and used as a medium for incorporation and release of the active substance. Stability of obtained films, as well as the electrochemical behaviour of ranitidine hydrochloride was investigated by cycling the potential of the film electrode in 0.9 % NaCl in the same potential window used for the polymerization. Uptake and release of the active substance was performed at constant potential and monitored by chronoamperometry. Although incorporation of the ranitidine hydrochloride was not obvious from the measured infrared spectra, incorporation and release was confirmed and quantified by monitoring the concentration of the active substance in the electrolyte. It was determined that maximum reversible uptake was 351 μg cm-2. However, successive potential stimuli did not result in the equal released quantity, as expected for the ideal controlled-release system based on conducting polymers

Controlled release of ranitidine from conductive polypyrrole films

Incorporation and controlled release of active substances from the conductive polypyrrole films by electric stimulation were investigated. Change of the redox state of the conductive polymer was induced by this stimulation, which allowed the incorporation and release of the drug at different rates. Polymerization of pyrrol on a stainless steel substrate was performed by cycling the potential 40 times in predetermined potential window, after which uniform polymeric film was formed and used as a medium for incorporation and release of the active substance. Stability of obtained films, as well as the electrochemical behaviour of ranitidine hydrochloride was investigated by cycling the potential of the film electrode in 0.9 % NaCl in the same potential window used for the polymerization. Uptake and release of the active substance was performed at constant potential and monitored by chronoamperometry. Although incorporation of the ranitidine hydrochloride was not obvious from the measured infrared spectra, incorporation and release was confirmed and quantified by monitoring the concentration of the active substance in the electrolyte. It was determined that maximum reversible uptake was 351 μg cm-2. However, successive potential stimuli did not result in the equal released quantity, as expected for the ideal controlled-release system based on conducting polymers

GALLIC ACID ANALYSIS BY HIGH-RESOLUTION LIQUID CHROMATOGRAPHY ON REVERSE PHASES IN RASPBERRY FLOWER EXTRACT (Rubus idaeus L.)

Gallic acid is a phenolic acid widely spread in various plants, where it is present either in free form or as part of tannins, called gallotannins. It shows several positive effects on human health. It has different biological effects: antibacterial, antiviral, anti-inflammatory. Many scientists are showing great interest in gallic acid precisely because of its antitumor effect. The content of gallic acid was determined in (Rubus idaeus L.) Polka raspberry by applying reverse-phase high-resolution liquid chromatography on reverse phases on Shimadzu Prominence Modular HPLC with UV/Vis detector, mobile phase degasser, pump, autosampler and column oven. The analysis was performed in ethanolic extracts of Polka raspberry flower obtained by the Soxhlet extraction and the ultrasonic methods. Raspberry flowers (Rubus idaeus L.) Polka varieties were collected from two different localities in Bosnia and Herzegovina, namely: Starposle near Kakanj and Moševac near Maglaj. Gallic acid was determined in all analyzed samples of Polka raspberry. The highest gallic acid content was determined in the extract of Polka raspberry flower from the Maglaj-Moševac site, using the ultrasonic method (0.1789%), and the smallest in the Polka raspberry flower from the Kakanj Starposle site, using Soxhlet extraction (0.0995%). The proportion of gallic acid was higher in the extract of Polka raspberry flower from the Maglaj-Moševac site, which suggests that these flowers of Polka variety are recommended as better natural sources of this phenolic acid and that ultrasonic extraction has proven to be a more efficient method for extraction of gallic acid in ethanolic extracts, which is the goal of research.&nbsp

Electrochemical tuning of capacitive response of graphene oxide

Increasing energy demands of modern society requires deep understanding of the properties of energy storage materials as well as their performance tuning. We show that the capacitance of graphene oxide (GO) can be precisely tuned using a simple electrochemical reduction route. In situ resistance measurements, combined with cyclic voltammetry measurement and Raman spectroscopy, have shown that upon the reduction GO is irreversibly deoxygenated which is further accompanied with structural ordering and increasing of electrical conductivity. The capacitance is maximized when the concentration of oxygen functional groups is properly balanced with the conductivity. Any further reduction and de-oxygenation leads to the gradual loss of the capacitance. The observed trend is independent on the preparation route and on the exact chemical and structural properties of GO. It is proposed that an improvement of capacitive properties of any GO can be achieved by optimization of its reduction conditions.Comment: 23 pages, 7 figures, 59 reference

THE CADMIUM, MERCURY AND IRON CONTENT IN LIVER AND KIDNEYS OF LAMBS IN THE MUNICIPAL AREA KAKANJ AND ZENICA

U radu su prikazani rezultati istraživanja opterećenosti teškim metalima na relaciji tlo-biljka-životinja područja Srednje-bosanskog kantona. Istraživanja su obuhvatila analizu sadržaja kadmija (Cd), žive (Hg) i željeza (Fe) u jetrenom i bubrežnom tkivu domaće janjadi. S područja općine Kakanj žrtvovano je 8 janjadi, od kojih su uzeti uzorci tkiva jetre i bubrega, a Zenice 7 janjadi, od kojih su također uzeti uzorci tkiva jetre i bubrega. Sadržaj teških metala (Cd, Hg i Fe) u uzetim uzorcima, utvrđen je na ICP-MS (masena spektrometrija s induktivno spregnutom plazmom), u skladu s evropskim standardima (EN 13805 : 2002, IDT) i (EN 15763, 2009, IDT). Utvrđena srednja količina Cd u uzorcima tkiva jetre s područja općine Kakanj iznosila je 0,115, a Zenice 0,261 mg/kg. Srednja vrijednost količine Cd u uzorcima tkiva bubrega sa područja općine Kakanj iznosila je 0,197, a Zenice 0,476 mg/kg. Sadržaj kadmija je veoma varijabilan na oba lokaliteta. Nije utvrđena statistički značajna razlika između lokaliteta. Općenito, sadržaj kadmija je ispod gornje granice dozvoljene količine prema Direktivi Europske Komisije. Utvrđene količine Fe na oba istraživana lokaliteta su znatno ispod gornje granice dozvoljenih vrijednosti. Na oba lokaliteta u uzetim uzorcima istraživanih tkiva nije utvrđena prisutnost žive.This paper presents the results of research on heavy metal load on the relation soil-plant-animal in the Central Bosnia Canton. This research included analysis of cadmium (Cd), mercury (Hg) and iron (Fe) content in liver and kidney tissue of domestic lambs. From the areas of Kakanj nad Zenica eight and seven lambs were sacrificed from which liver and kidney samples were taken. Heavy metals concentration in samples was determined using the ICP-MS (Inductively coupled plasma mass spectrometry), in accordance with European standards (EN 13805:2002, IDT) and (EN 15763,2009, IDT). Mean Cd content in samples of liver tissue was 0.115 ppm in Kakanj municipality, and 0.261 ppm in Zenica municipality. Mean Cd content in samples of kidney tissue was 0.197 ppm in Kakanj municipality and 0.476 in Zenica municipality. Cadmium content was very variable in both regions. Cd content was below the upper limit of allowable quantity according to EU regulations. Determined amounts of iron in both regions were well below the upper limit of allowed quantities. In both regions mercury was not found

Electrochemical tuning of capacitive response of graphene oxide

The increasing energy demands of modern society require a deep understanding of the properties of energy storage materials, as well as the tuning of their performance. We show that the capacitance of graphene oxide (GO) can be precisely tuned using a simple electrochemical reduction route. In situ resistance measurements, in combination with cyclic voltammetry measurements and Raman spectroscopy, have shown that upon reduction GO is irreversibly deoxygenated, which is further accompanied by structural ordering and an increase in electrical conductivity. The capacitance is maximized when the concentration of oxygen functional groups is properly balanced with the conductivity. Any further reduction and deoxygenation leads to a gradual loss of capacitance. The observed trend is independent of the preparation route and the exact chemical and structural properties of GO. It is proposed that an improvement in the capacitive properties of any GO can be achieved by optimization of its reduction conditions.This is the peer-reviewed version of the following article: Gutić, Sanjin J., Dževad Kozlica, Fehim Korać, Danica Bajuk-Bogdanović, Miodrag Mitrić, Vladimir M. Mirsky, Slavko V. Mentus, and Igor A. Pašti. "Electrochemical tuning of capacitive response of graphene oxide." (2018). [https://doi.org/10.1039/C8CP03631D]Published version available at: [http://vinar.vin.bg.ac.rs/handle/123456789/7877

In vitro fluoride release from a different kind of conventional and resin modified glass-ionomer cements

Fluoride release is important characteristic of glass-ionomer cements. Quantity of fluoride ions released from the glass-ionomer cements has major importance in definition of their biological activity. The objectives of this study were to define the quantity of fluoride ions released from the experimental glass-ionomer cements and to define the effect of fluoride ions released from the experimental glass-ionomer cements on their cytotoxicity. Concentrations of the fluoride ions released in the evaluated glass-ionomer cements were measured indirectly, by the fluoride-selective WTW, F500 electrode potential, combined with reference R503/D electrode. Statistical analyses of F-ion concentrations released by all glass-ionomers evaluated at two time points, after 8 and after 24 hours, show statistically higher fluoride releases from RMGICs: Vitrebond, Fuji II LC and Fuji Plus, when compared to conventional glass-ionomer cements: Fuji Triage, Fuji IX GP Fast and Ketac Silver, both after 8 and after 24 hours. Correlation coefficient between concentrations of fluoride ion released by evaluated glass-ionomer cements and cytotoxic response of UMR-106 osteoblast cell-line are relatively high, but do not reach levels of biological significance. Correlation between concentrations of fluoride ion released and cytotoxic response of NIH3T3 mouse fibroblast cell line after 8 hours is high, positive and statistically significant for conventional GICs, Fuji Triage and Fuji IX GP Fast, and RMGIC, Fuji II LC. Statistically significant Correlation coefficient between concentrations of fluoride ion released and cytotoxic response of NIH3T3 cell line after 24 hours is defined for RMGIC Fuji II LC only