Jedním z problémů při kloubních náhradách jsou komplikace spojené s pooperačními infekcemi. Infekce způsobené bakteri-emi, které tvoří biofilmy na površích, se nazývají infekce související s biofilmem (biofilm related infections, BRI). V důsledku následné biologické odezvy organismu dochází k silným patofyziologickým změnám vmikroklimatu kolem takto postiženého povrchu (pokles pH, tvorba různých reaktivních forem kyslíku (ROS), vyčerpání iontů železa a zvýšení koncentrace vápenatých iontů). Vytvořili jsme robustní selektivní polymerní potenciometrický senzor ROS a pH senzor pro detekci změn způsobených sterilním zánětem a bakteriálními a plísňovými infekcemi. Senzor ROS se skládá z vodivé polymerní vrstvy na bázi polythiofenu se zabudovaným komplexem porfyrin-kov, který potenciometricky deteguje přítomnost ROS, jak bylo demonstrováno na peroxi-du vodíku. Tento senzor je kovalentně potažen vrstvou odolnou biopasivaci (non-biofouling layer, NBL) tvořenou poly(2-methyl--2-oxazolin)em, která funguje jako biokompatibilizátor.Bylo prokázáno, že potenciometrický senzor vykazuje rychlou odezvu naperoxid vodíku, nezaznamenává interferenci s hovězím sérovým albuminem jako modelovým sérovým proteinem a je schopenplně reverzibilně detegovat ROS s lineární odezvou v širokém rozsahu biologicky relevantních koncentrací (od 0,05μM do10μM). Polymerní pH senzor na bázi polyanilinu a poly(2-methyl-2-oxazolinu) na nosiči z titanové slitiny byl vyvinut pro po-tenciometrickou detekci změn pHv okolí implantátu, aby bylo možné včas detegovat výše uvedené záněty. Vyvinuté elektrody měří změnu pH v rozsahu pH5 až 8, tedy vrozmezí relevantním pro jednotlivé infekce baktériemi a kvasinkami.
One of the problems occurring after the joint replace-ment is connected with the post-surgery infections which are caused by bacteria that form biofilms on surfaces and are referred to as biofilm-related infections (BRI). It is also worth noting that due to the bioresponse, strong path-ophysiologicalchangesinthemicroclimateofanaffectedsurface occur (decrease in pH, formation of various reac-tive oxygen species (ROS), depletion of Fe ions, and in-crease in the concentration of Ca ions). In this work we have prepared a robust selective potentiometric sensorof ROS and pH sensor for the detection of pH changes caused by sterile inflammation and bacterial and fungal infections. The ROS sensor consists of a conductive poly-mer layer based on polythiophene with an incorporated porphyrin-metal complex that potentiometrically detects the presence of ROS (H2O2and ClO–ions). This sensor is connected by the covalent bonds with a non-biofouling layer of poly(2-methyl-2-oxazoline), which works as abio-compa-tibilizer. It was shown that the potentiometric sen-sor shows a rapid response to hydrogen peroxide, does not record any interference with bovine serum albumin as amodel serum protein, and is able to fully reversibly de-tect ROS with a linear response within a wide range of biological relevant concentrations (from 0.05 μM to 10μM). The sensing electrode based on polyaniline and poly(2-methyl-2-oxazoline) on a titanium alloy support was developed for the potentiometric detection of peri-implant pH changes to enable early detection of the afore-mentioned pathologies. The developed electrodes show the changing of pH in the range between 5 and 8 for the individual pathogenic bacteria or pathogenic yeast, with aNernstian slope of −59.6/pH.
- Klíčová slova
- potenciometrický senzor,
- MeSH
- biofilmy MeSH
- klouby chirurgie mikrobiologie MeSH
- koncentrace vodíkových iontů MeSH
- lidé MeSH
- potenciometrie * metody přístrojové vybavení MeSH
- protézy kloubů mikrobiologie MeSH
- reaktivní formy kyslíku analýza MeSH
- výzkum MeSH
- zánět diagnóza etiologie prevence a kontrola MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
Na základě údajů v Ph. Eur., v některých dalších nověj- ších lékopisech a v publikovaných experimentálních pracích je navrženo revidovat text Ph. Eur. 2.5.8. V první řadě je třeba specifikovat, která z elektrometrických metod má být k instrumentální indikaci konečného bodu diazotačních titrací v Ph. Eur. použita (nejlépe potenciometrie s platinovou indikační elektrodou). Množství bromidu draselného v roztoku k titraci lze snížit na 1 g, chlazení roztoku před titrací z rámcového postupu vypustit a uvést až v jednotlivých monografiích, pokud bude u některých léčiv k získání přesných a správných výsledků potřebné. Diazotační titraci lze v Ph. Eur. využít ke stanovení obsahu i u některých dalších léčiv.
Based on the data in the Ph. Eur., some other newer pharmacopoeias and published experimental papers propose to revise the text of Ph. Eur. 2.5.8. First, it is necessary to specify which of the electrometric methods should be used to indicate the endpoint of diazotization titrations in Ph. Eur. (preferable potentiometry with a platinum indicating electrode). The amount of potassium bromide in the titration solution may be reduced to 1 g, the cooling of the solution before titration may be omitted from the framework procedure, and it may be specified in individual monographs if necessary to obtain accurate and correct results for some medicines. Diazotization titration can be performed in Ph. Eur. and can also be used to determine the content of some other medicines.
- MeSH
- dusitan sodný MeSH
- farmakopea jako téma MeSH
- léčivé přípravky * analýza MeSH
- lidé MeSH
- potenciometrie metody MeSH
- řízení kvality MeSH
- titrace * MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Evropa MeSH
Three 1,4,7,10-tetraazacyclododecane-based ligands disubstituted in 1,4-positions with phosphonic acid, phosphonate monoethyl-ester, and H-phosphinic acid pendant arms, 1,4-H4do2p, 1,4-H2do2pOEt, and 1,4-H2Bn2do2pH, were synthesized and their coordination to selected metal ions, Mg(II), Ca(II), Mn(II), Zn(II), Cu(II), Eu(III), Gd(III), and Tb(III), was investigated. The solid-state structure of the phosphonate ligand, 1,4-H4do2p, was determined by single-crystal X-ray diffraction. Protonation constants of the ligands and stability constants of their complexes were obtained by potentiometry, and their values are comparable to those of previously studied analogous 1,7-disubstitued cyclen derivatives. The Gd(III) complex of 1,4-H4do2p is ~1 order of magnitude more stable than the Gd(III) complex of the 1,7-analogue, probably due to the disubstituted ethylenediamine-like structural motif in 1,4-H4do2p enabling more efficient wrapping of the metal ion. Stability of Gd(III)-1,4-H2do2pOEt and Gd(III)-H2Bn2do2pH complexes is low and the constants cannot be determined due to precipitation of the metal hydroxide. Protonations of the Cu(II), Zn(II), and Gd(III) complexes probably takes place on the coordinated phosphonate groups. Complexes of Mn(II) and alkali-earth metal ions are significantly less stable and are not formed in acidic solutions. Potential presence of water molecule(s) in the coordination spheres of the Mn(II) and Ln(III) complexes was studied by variable-temperature NMR experiments. The Mn(II) complexes of the ligands are not hydrated. The Gd(III)-1,4-H4do2p complex undergoes hydration equilibrium between mono- and bis-hydrated species. Presence of two-species equilibrium was confirmed by UV-Vis spectroscopy of the Eu(III)-1,4-H4do2p complex and hydration states were also determined by luminescence measurements of the Eu(III)/Tb(III)-1,4-H4do2p complexes.
- MeSH
- europium chemie MeSH
- gadolinium chemie MeSH
- heterocyklické sloučeniny chemie MeSH
- komplexní sloučeniny chemická syntéza chemie MeSH
- kontrastní látky MeSH
- krystalografie rentgenová MeSH
- kyseliny fosfinové chemie MeSH
- ligandy MeSH
- magnetická rezonanční spektroskopie MeSH
- mangan chemie MeSH
- organofosfonáty chemie MeSH
- potenciometrie MeSH
- spektrofotometrie ultrafialová MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
Potentiometric and spectrophotometric pH-titrations of the lesinurad for three consecutive dissociation constants determination were compared. Lesinurad is a selective inhibitor of uric acid reabsorption as part of a combination of medicines to treat high levels of uric acid in blood, also called hyperuricemia. Nonlinear regression of the pH-spectra with REACTLAB and SQUAD84 and of the pH-titration curve with ESAB determined three multiple close dissociation constants. The protonation scheme of lesinurad was suggested. A sparingly soluble anion L- of lesinurad was protonated to the still soluble species LH, LH2+ and LH32+ in pure water. Three consecutive thermodynamic dissociation constants were estimated pKTa1 = 2.09, pKTa2 = 4.25, pKTa3 = 6.58 at 25 °C and pKTa1 = 1.96, pKTa2 = 4.16, pKTa3 = 6.32 at 37 °C by UV-metric spectra analysis. The graph of molar absorption coefficients shows that the spectrum of species LH2+ and LH vary in colour, while protonation of chromophore LH2+ to LH32+ has less influence on chromophores in the lesinurad molecule. Three multiple thermodynamic dissociation constants of 1 × 10-4 M lesinurad were determined by the pH-metric analysis pKTa1 = 2.39, pKTa2 = 3.47, pKTa3 = 6.17 at 25 °C and pKTa1 = 2.08, pKTa2 = 3.29, pKTa3 = 6.03 at 37 °C. The values of enthalpy ΔH0(pKa1) = 19.19 kJ mol-1, ΔH0(pKa2) = 13.29 kJ mol-1, ΔH0(pKa3) = 38.39 kJ mol-1, show the dissociation process is endothermic. The positive values of ΔG0(pKa1) = 11.93 kJ mol-1, ΔG0(pKa2) = 24.26 kJ mol-1, ΔG0(pKa3) = 37.56 kJ mol-1 at 25 °C indicate that the dissociation process of pKa2 is not spontaneous, which was confirmed by its value of entropy ΔS0(pKa1) = 24.37 J mol-1, ΔS0(pKa2) = -36.79 J mol-1, ΔS0(pKa3) = 2.79 J mol-1. Three macro-dissociation constants of lesinurad and protonation locations were predicted by MARVIN and ACD/Percepta.
- MeSH
- chemie farmaceutická MeSH
- koncentrace vodíkových iontů MeSH
- potenciometrie přístrojové vybavení metody MeSH
- spektrofotometrie ultrafialová přístrojové vybavení metody MeSH
- termodynamika * MeSH
- thioglykoláty chemie MeSH
- triazoly chemie MeSH
- urikosurika chemie MeSH
- Publikační typ
- časopisecké články MeSH
Potentiometric and spectrophotometric pH-titration of the multiprotic cytostatics bosutinib for dissociation constants determination were compared. Bosutinib treats patients with positive chronic myeloid leukemia. Bosutinib exhibits four protonatable sites in a pH range from 2 to 11, where two pK are well separated (ΔpK>3), while the other two are near dissociation constants. In the neutral medium, bosutinib occurs in the slightly water soluble form LH that can be protonated to the soluble cation LH4(3+). The molecule LH can be dissociated to still difficultly soluble anion L(-). The set of spectra upon pH from 2 to 11 in the 239.3-375.0nm was divided into two absorption bands: the first one from 239.3 to 290.5nm and the second from 312.3 to 375.0nm, which differ in sensitivity of chromophores to a pH change. Estimates of pK of the entire set of spectra were compared with those of both absorption bands. Due to limited solubility of bosutinib the protonation in a mixed aqueous-methanolic medium was studied. In low methanol content of 3-6% three dissociation constants can be reliably determined with SPECFIT/32 and SQUAD(84) and after extrapolation to zero content of methanol they lead to pKc1=3.43(12), pKc2=4.54(10), pKc3=7.56(07) and pKc4=11.04(05) at 25°C and pKc1=3.44(06), pKc2=5.03(08) pKc3=7.33(05) and pKc4=10.92(06) at 37°C. With an increasing content of methanol in solvent the dissociation of bosutinib is suppressed and the percentage of LH3(2+) decreases and LH prevails. From the potentiometric pH-titration at 25°C the concentration dissociation constants were estimated with ESAB pKc1=3.51(02), pKc2=4.37(02), pKc3=7.97(02) and pKc4=11.05(03) and with HYPERQUAD: pKc1=3.29(12), pKc2=4.24(10), pKc3=7.95(07) and pKc4=11.29(05).
- MeSH
- aniliny analýza chemie MeSH
- chinoliny analýza chemie MeSH
- cytostatické látky analýza chemie MeSH
- koncentrace vodíkových iontů MeSH
- metoda nejmenších čtverců MeSH
- nelineární dynamika * MeSH
- nitrily analýza chemie MeSH
- potenciometrie MeSH
- spektrofotometrie metody MeSH
- Publikační typ
- časopisecké články MeSH
Electrochemistry of nucleic acid is at present a booming field producing about 800 papers published per year. First papers in this field were published in 1958–1961 in Brno (Czech Republic) showing that purine and pyrimidine base residues in single-stranded DNA and RNA were reduced at Hg electrodes and the guanine residue produced an anodic signal when cyclic modes were used. The reduction sites of the base residues in native double-stranded (ds) DNA are hidden in the interior of the dsDNA molecule, which made their reduction difficult. At that time oscillographic polarography (ac chronopotentiometry) showed excellent sensitivity to changes in DNA structure and allowed to investigate DNA denaturation and hybridization. Later on also other electrochemical methods and electrodes were applied. In the following three decades basic principles were found which are at present used in the development of DNA hybridization sensors.
- MeSH
- chromozomy chemie MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- DNA * analýza chemie MeSH
- elektrochemické techniky dějiny metody MeSH
- elektrochemie * dějiny metody MeSH
- plazmidy analýza chemie MeSH
- polarografie dějiny metody MeSH
- potenciometrie dějiny metody MeSH
- RNA transferová analýza chemie MeSH
- RNA virová analýza chemie MeSH
- Check Tag
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- Publikační typ
- historické články MeSH
- práce podpořená grantem MeSH
- MeSH
- biosenzitivní techniky * dějiny metody přístrojové vybavení trendy využití MeSH
- diabetes mellitus diagnóza krev MeSH
- enzymy biosyntéza MeSH
- glukosa analýza chemie MeSH
- krevní glukóza MeSH
- lidé MeSH
- nanočástice využití MeSH
- potenciometrie přístrojové vybavení MeSH
- selfmonitoring glykemie * přístrojové vybavení trendy MeSH
- Check Tag
- lidé MeSH
As-cast Mg-Sn, Mg-Ga and Mg-In alloys containing 1-7 wt.% of alloying elements were studied in this work. Structural and chemical analysis of the alloys was performed by using light and scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction, x-ray photoelectron spectroscopy and glow discharge spectrometry. Mechanical properties were determined by Vickers hardness measurements and tensile testing. Corrosion behavior in a simulated physiological solution (9 g/l NaCl) was studied by immersion tests and potentiodynamic measurements. The cytotoxicity effect of the alloys on human osteosarcoma cells (U-2 OS) was determined by an indirect contact assay. Structural investigation revealed the dendritic morphology of the as-cast alloys with the presence of secondary eutectic phases in the Mg-Sn and Mg-Ga alloys. All the alloying elements showed hardening and strengthening effects on magnesium. This effect was the most pronounced in the case of Ga. All the alloying elements at low concentrations of approximately 1 wt.% were also shown to positively affect the corrosion resistance of Mg. But at higher concentrations of Ga and Sn the corrosion resistance worsened due to galvanic effects of secondary phases. Cytotoxicity tests indicated that Ga had the lowest toxicity, followed by Sn. The most severe toxicity was observed in the case of In.
- MeSH
- biokompatibilní materiály chemie farmakologie MeSH
- buněčná smrt účinky léků MeSH
- fotoelektronová spektroskopie MeSH
- koroze MeSH
- kovy farmakologie MeSH
- lidé MeSH
- mechanické jevy účinky léků MeSH
- mikroskopie elektronová rastrovací MeSH
- nádorové buněčné linie MeSH
- pevnost v tahu účinky léků MeSH
- potenciometrie MeSH
- slitiny chemie farmakologie MeSH
- testování materiálů * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Boli vypracované modifikované postupy stanovenia obsahu vybratých solí dusík obsahujúcich organických zásad alkalimetrickou titráciou v prostredí etanolu 70 % a kyseliny chlorovodíkovej 0,01 mol/l, v prostredí samotného etanolu 70 %, resp. etanolu 96 % s potenciometrickou indikáciou konca titrácie. Výsledky stanovenia obsahu vybratých substancií liečiv porovnávame s výsledkami stanovenia obsahu týchto liečiv v Ph. Eur. 7 Ed. V skupine 11 nami analyzovaných liečiv predpisuje Ph. Eur. 7th Ed. uvedenú alkalimetrickú titráciu pre 8 liečiv: Cinchocaine hydrochloride, Codeine hydrochloride dihydrate, Ethylmorphine hydrochloride, Lidocaine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride, Quinine hydrochloride, Tetracaine hydrochloride. Pri 5 liečivách z tejto skupiny: Cinchocaine hydrochloride, Ethylmorphine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride a Tetracaine hydrochloride metóda neposkytuje výsledky zhodné s deklarovaným obsahom liečiv v príslušných liekopisných článkoch. Do súboru 11 analyzovaných liečiv sme zaradili aj liečivá charakteru slabých organických zásad, pre ktoré liekopis predpisuje iné postupy stanovenia obsahu: pre Thiamine hydrochloride a Pyridoxine hydrochloride je v liekopise predpísaná acidimetrická titrácia odmerným roztokom kyseliny chloristej v nevodnom prostredí a pre liečivo Procaine hydrochloride je to nitritometria, t.j. stanovenie dusíka v primárnych aromatických amínoch.
Modified methods – alkalimetry in ethanol 70% with a defined small volume of hydrochloric acid 0.01 mol/l added to the solution of the sample before the titration and alkalimetry in ethanol 70% or ethanol 96% alone with potentiometric end-point detection for the assay of halide salts of 11 organic N-bases has been investigated. The results were compared to those obtained by the method of the European Pharmacopoeia 7th Ed. (Ph. Eur. 7th Ed.). The Ph. Eur. 7th Ed. use for 8 investigated substances alkalimetry in alcohol 96 % with a defined small volume of hydrochloric acid 0.01 mol/l (5 ml) with potentiometric end-point detection: Cinchocaine hydrochloride, Codeine hydrochloride dihydrate, Ethylmorphine hydrochloride, Lidocaine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride, Quinine hydrochloride, Tetracaine hydrochloride. Our results revealed that the Ph. Eur. 7th Ed. method did not work for 5 drugs from this group: Cinchocaine hydrochloride, Ethylmorphine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride and Tetracaine hydrochloride. In the group of investigated substances we included also drugs with the character of weak organic bases for which Ph. Eur. 7th Ed. prescribed different methods for their assay: Thiamine hydrochloride and Pyridoxine hydrochloride – acidimetric titration in non-aqueous solvents with perchloric acid and Procaine hydrochloride – determination of primary aromatic amino-nitrogen (Ph. Eur. 7th Ed., chapter 2.5.8).
- MeSH
- chemické techniky analytické * MeSH
- chemie analytická MeSH
- chemie farmaceutická MeSH
- farmakopea jako téma MeSH
- léčivé přípravky * analýza chemie MeSH
- lidé MeSH
- metody pro přípravu analytických vzorků * MeSH
- organické látky analýza chemie MeSH
- potenciometrie MeSH
- titrace MeSH
- Check Tag
- lidé MeSH
In this research, binary Mg-Zn (up to 3 wt% Zn) and ternary Mg-Zn-Gd (up to 3 wt% Gd, 3 wt% Zn) alloys were prepared by induction melting in an argon atmosphere. The structures of these alloys were characterized using light and scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and X-ray fluorescence. In addition, Brinell hardness measurements were taken to supplement these studies. Corrosion behavior was evaluated by immersion tests and potentiodynamic measurements in a physiological solution (9 g/l NaCl). Depending on the composition, structures of the as-cast alloys contained α-Mg dendrites, MgZn, Mg5Gd and Mg3Gd2Zn3 phases. Compared to pure Mg, zinc improved the corrosion resistance of binary Mg-Zn. Gadolinium also improved the corrosion resistance in the case of Mg-1Zn-3Gd alloy. The highest corrosion rate was observed for Mg-3Zn-3Gd alloy. Our results improve the understanding of the relationships between the structure and corrosion behavior of our studied alloy systems.
- MeSH
- difrakce rentgenového záření MeSH
- gadolinium chemie MeSH
- hořčík chemie MeSH
- koroze MeSH
- mikroskopie elektronová rastrovací MeSH
- osmolární koncentrace MeSH
- potenciometrie MeSH
- slitiny chemie MeSH
- testování materiálů MeSH
- tvrdost MeSH
- vstřebatelné implantáty MeSH
- zinek chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
