Профиль высвобождения активного ингредиента из наночастиц является одним из важнейших параметров наносомальной лекарственной формы. Разработаны и оптимизированы методы изучения кинетики высвобождения доксорубицина из наночастиц PLGA в модельные среды in vitro. Оптимальным методом отделения наночастиц является ультрацентрифугирование, а наиболее подходящей модельной средой — 1 % водный раствор полоксамера 188. Профиль высвобождения имеет выраженный двухфазный характер и подчиняется закону диффузии Фика. Изучение кинетики высвобождения доксорубицина в плазме крови ограничено низкой стабильностью в условиях эксперимента (4 ч при 37 °C).

Arylsulfatase A (ASA) deficiency is the cause of metachromatic leucodystrophy (MLD), a lysosomal storage disease associated with severe neurological disorders. Poly(butyl cyanoacrylate) (PBCA) nanoparticles overcoated with polysorbate 80 enabled the delivery of several drugs across the blood-brain barrier to the brain suggesting that these nanoparticles also may transport ASA across this barrier. The objective of this research, therefore, was to evaluate the feasibility of loading ASA onto PBCA nanoparticles. A stable ASA-loaded PBCA nanoparticle formulation was developed that could be easily freeze-dried and stored over a period of more than 8 weeks. The maximum loading capacity for this enzyme was -59 microg per 1 mg of PBCA. In the presence of 3% sucrose as a lyoprotector the activity of freeze-dried ASA was found to be 100% recoverable.

Методом вольтамперометрии на границе раздела двух несмешивающихся растворов электролитов изучен перенос ионов щелочных и щелочноземельных металлов, а также иона аммония, индуцированный каликсаренами 5,11,17,23-тетра(трет-бутил)-26,28-дигидроксикаликс[4]-25,27-краун-5 эфир, 5,11,17,23-тетра(трет-бутил)-26,28-ди(этоксикарбонилметокси)каликс[4]-25,27-краун-5 эфир, 5,11,17,23-тетра(трет-бутил)-25,26,27,28-тетра(этоксикарбонилметокси)-каликс[4]арен. Определены формальные энергии и потенциалы переноса образующихся комплексов, стехиометрия и значения констант устойчивости. На основании данных исследований подобраны оптимальные условия для определения иона аммония методом вольтамперометрии на границе раздела жидкость/жидкость (предел обнаружения составил 3.5 ? 10-6 М). Показана селективность определения иона аммония по отношению к ионам натрия.

The transfer of alkali and alkaline earth metal ions and ammonium ions facilitated by the calixarenes 5,11,17,23-tetra(tert-butyl)-26,28-dihydroxycalix[4]-25,27-crown-5-ether, 5,11,17,23-tetra(tert-butyl)-26,28-di(ethoxycarbonylmethoxy)calix[4]-25,27-crown-5-ether, and 5,11,17,23-tetra(tert-butyl)-25,26,27,28-tetra(ethoxycarbonylmethoxy)-calix[4]arene was studied by voltammetry at the interface between two immiscible electrolyte solutions. The formal energies, transfer potentials, stoichiometry, and stability constants of the complexes were determined. The optimum conditions for determining the ammonium ion by voltammetry at the liquid-liquid interface were selected on the basis of these studies (the detection limit was 3.5 × 10−6 M). The ammonium ion determination showed selectivity relative to the sodium ion.

Методом вольтамперометрии на границе раздела двух несмешивающихся растворов электролитов (ГРДНРЭ) исследован перенос аминогликозидных антибиотиков (стрептомицина, канамицина и гентамицина), индуцированный дибензо-18-краун-6. Сделано предположение о стехиометрии образующихся комплексов (1 : 1). Предложено использовать данный метод для определения канамицина и стрептомицина в водных растворах. Установлены оптимальные условия определения этих аминогликозидов, пределы обнаружения стрептомицина 8.0 ? 10-5 М, канамицина 2.0 ? 10-4 М. Изучена селективность определения стрептомицина методом вольтамперометрии на ГРДНРЭ в присутствии ионов калия и натрия. Разработан амперометрический ионселективный электрод для определения стрептомицина в лекарственной форме (предел обнаружения: 9.0 ? 10-5 М).

The transfer of aminoglycoside antibiotics streptomycin, kanamycin, and gentamycin induced by dibenzo-18-crown-6 is studied by voltammetry at the interface of two immiscible electrolyte solutions ( ITIES ). An assumption about the 1: 1 stoichiometry of the complexes formed is formulated. The method is proposed for use in the analysis of kanamycin and streptomycin in aqueous solutions. The optimal conditions of analysis of these aminoglycosides are found, the detection limits are 8.0 × 10 −5 M for streptomycin and 2.0 × 10 −4 M for kanamycin. The selectivity of streptomycin analysis by ITIES voltammetry in presence of potassium and sodium is studied. An amperometric ion-selective electrode is developed for the determination of streptomycin in drug formulations with a detection limit of 9.0 × 10 −5 M.

Transfer of complexes of josamycin, spyramycin, and erythromycin with alkali and alkali-earth metals was studied using the method of voltammetry at the interface of two immiscible electrolyte solutions. Standard energies and standard transfer potentials of the formed complexes and also the values of their stability constants were determined. Stoichiometry of the complexes formed was determined. Experimentally obtained detection limits of these macrolide antibiotics in the organic phase are presented.

To establish the composition of the gentamicin complex (GNMC) of copper(II) in the polymer matrix of an ion-selective membrane (ISM), we investigated spectra of the ISM upon both incorporation of the GNMC and its complex with copper(II) by the IR spectrometry method. A number of spectral changes were revealed: the appearance and disappearance of some absorption bands and batho- and hypsochromic shifts accompanied by the substantial rearrangement of the bands’ intensities. The observed effects are indicative of the change of the distribution of the charge within the molecule, the formation of new bonds, and rotational transformation in the formation of a chelate cycle. This confirms not only the presence of a complex in the polymer matrix but also that its structure is identical to the one found in solution before.

The complexation of aminoglycoside antibiotics with metal cations was proposed as a derivatization method for the further determination of the complex obtained by potentiometry with ion-selective electrodes ( ISE ), voltammetry at the interface between two immiscible electrolyte solutions ( ITIES ), and spectrophotometry. It was shown by the spectrophotometric method that gentamicin formed a 1: 1 complex with copper(II). For the potentiometric determination of gentamicin, we obtained ionophores that were ion associates formed by the gentamicin complex of copper(II) and tetraphenylborate derivatives as counterions. The transfer of the gentamicin complex of copper(II) was studied voltammetrically at the ITIES. The results obtained indicate that l antibiotic gentamicin can be directly determined as a complex with copper(II) by potentiometric, voltammetric, and spectrophotometric methods.

On the basis of existent data we have carried out a comparative analysis of equilibriums of formation and distribution of metal complexes in extraction and ionometry with liquid and plasticized ion-selective electrodes. We have shown that electrode-active compounds are practically identical to compounds formed via extraction, and hence common behavioural patterns and clas-sification of ionometric systems correspond to the patterns found in extraction systems. Distribution processes, which take place in the ion-sensitive membrane, may be considered as being common for bi-phase systems, primarily extrationary, whereby reactions of formation and distribution take place. This approach provides well-grounded explanation for an array of experimentally de-termined facts: for instance association between sensitivity and selectivity of ion-selective electrodes and resistance of complexes, utilized as electrode-active compounds; hydrophobicity of complex and ligands; as well as the nature of the membrane dissolving agent.

Molecularly selective field-effect transistors are developed for determining oxidized and reduced forms of nicotinamide adenine dinucleotides (NAD + and NADH) and their phosphates (NAD(P) + and NAD(P)H). Copolymers of acrylamide and acrylamidophenylboric acid imprinted with corresponding nucleotides are used as sensing elements of sensors. After washing out a nucleotide, a cavity corresponding to the surface of the imprinted nucleotide is retained and ensures the selectivity of the sensor. At the same time, sensors containing any of the nucleotides of interest in solutions demonstrate almost equal sensitivities of 10 −7 M. The properties of the sensors are explained by the structure of the nucleotides and the composition of the membranes.

Macrophages in the lungs are the most important cell type supporting replication of Mycobacterium tuberculosis in humans. The objective of this study was to investigate whether the effect of moxifloxacin against M. tuberculosis residing in macrophages could be improved by encapsulation of the drug in the biodegradable nanoparticles, which are known to accumulate in macrophages upon intravenous administration. To accomplish this, moxifloxacin was encapsulated in poly(butyl cyanoacrylate) (PBCA) nanoparticles. Encapsulated moxifloxacin accumulated in macrophages approximately three-fold times more efficiently than the free drug, and was detected in the cells for at least six times longer than free moxifloxacin at the same extracellular concentration. Inhibition of intracellular M. tuberculosis growth with encapsulated moxifloxacin was achieved at the concentration of 0.1μg/ml, whereas the same effect with free MX required a concentration of 1μg/ml. Nanoparticles observed within the macrophage cytoplasm were distributed throughout the cytoplasm, sometimes in the vicinity of intracellular bacteria.

The selectivity and sensitivity of ion-selective electrodes (ISEs) based on membranes with phosphoryl-containing ionophores and lipophilic anion exchangers were studied. The analytical properties of the ISEs can be significantly modified and their selectivity for alkali and alkaline-earth metals can be even reversed by changing the membrane composition.

The induced transfer of ions of alkaline and alkaline-earth metals (AAEM) through the water/nitrobenzene interface with use of dicyclohexyl-18-crown-6 (DCH-18-C-6) is studied by the voltammetry technique at the interface between two immiscible electrolyte solutions (ITIES). The standard potentials and standard energies of the transfer of the complexes, their stoichiometry and stability constants in nitrobenzene are determined. It is found that all ions form with DCH-18-C-6 complexes MLZ+. Two models of the metal ion transfer induced by the ionophore are discussed: the ionophore distribution model and the metal distribution model. It is found that the completeness of a description of the experimental data within one model or another depends on properties of the metal, ionophore, and complex, and on experimental conditions. Essential requirements for the supporting electrolytes of the aqueous and organic phases are formulated. The factors affecting the selectivity and assay limit of the voltammetry at ITIES are discussed. Procedures for the voltammetric assay of the potassium and rubidium ions are developed.

ABSTRACT Predicting the effectiveness of liquid-liquid extraction of metal chelates and choosing optimal extraction reagents requires several characteristics of the components of the extraction system to be taken into consideration. This paper provides an analysis of the factors that affect the value of the partition constant of a chelate and the possibilities to predict the value of the partition constant from the nature of the metal ion, the structure of the chelating reagent, and the organogenic elements, one might have expected these techniques to be capable to predict the partition constants of chelates as well. However, the problem of determining the increments of metals turned out to be very difficult even in the case of relatively simple complexes. An analysis of the partition constants of coordinatively-saturated metal acetylacetonates has shown that the values depend on a large number of parameters, some of which are correlated. The central metal atom modifies the donor properties of the heteroa...

The potential usefulness of ionometry in the analytical control of plating electrolytes, etching solutions, and waste effluents has been considered. Complete ionometric analysis of plating electrolytes and determination of metal cyanide complexes have been presented as examples. Ion-selective field-effect transistors (IEFT), semiconductor electrodes, and ISE pairs have been shown to have potential usefulness for the potentiometric titration of plating electrolytes.