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EN
Biocatalysts with microorganisms immobilized on solid carriers could provide the solution for development of continuous industrial processes for ethanol obtaining by fermentation of sugars. In this study, modified polyacrylamide hydrogels and marrow stem sunflower are used as supports for Saccharomyces cerevisiae yeast immobilization. The obtained structures are used for fermentation of molasses in batch systems. The free yeast cells are used as reference. The modification of polyacrilamide matrix with (2-hydroxyethyl)methacrylate has a positive effect on structure pore uniformity and fermentation performance. The mechanical properties of the obtained biocatalysts are compared. The novel natural matrix has net superior compression strength.
EN
Standardized analytical methods for testing pharmaceutical preparations are not readily available in the literature for calcium dobesilate hydrogels. The aim of the study was to develop and validate analytical method for methylcellulose gel containing calcium dobesilate as an active ingredient. Samples from dissolution experiments were assessed via HPLC with UV-VIS detector. The optimal composition of mobile phase included acetonitrile with water 1:1, acidified to 2.5 pH value. The applied column was Standard Purospher Star 18e 250 x 4.6 (5µm), and the maximum wavelength was set on 240 nm, at 25 °C. The total run time of analysis was set at 5 min and acquired retention time was 2.7 and 3.1 min for calcium dobesilate depending on the hydrogel formulation. Validity study of the method revealed that all obtained calibration curves showed good linearity (r2 > 0.9927). Linearity (100% level) was found to be 99.42, 100.12, 99.48, 99.89, 100.70, 100.08, 99.82, 100.23 for A, B, C, D, E, F, G and H formulation, respectively. Accuracy was in the range of 98-102% on three different spike levels for all eight formulations. Precision results was around 100% with RSD lower than 1% in all cases indicating that the method can be used as a validated method. Limit of quantitation (LOQ) was found to be 13.25 μg∙ml-1 for all eight formulations. The method is feasible for evaluation of hydrophilic gels with calcium dobesilate.
Open Chemistry
|
2012
|
vol. 10
|
issue 4
1349-1359
EN
An acrylic acid/poly(ethylene glycol) (AAc/PEG) hydrogel was synthesized in aqueous solution by a simple one-step method using glow-discharge electrolysis plasma (GDEP) technique. The structure of AAc/PEG hydrogel was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Factors influencing the adsorption of heavy-metal ions such as solution pH, contact time, initial heavy-metal ion concentration were examined systematically by batch experiments. Results showed that both chemical complexation and ion exchange played an important role for heavy-metal ion adsorption onto AAc/PEG hydrogel. The adsorption isothermals followed the Langmuir isotherm and the adsorption kinetics fitted the pseudo-second-order model at 25°C with a pH 6. In addition, AAc/PEG hydrogel can be also regenerated and re-used. [...]
EN
Xanthan gum-based hydrogel formulation FXG3 was prepared by a free radical polymerization technique. To assess safety of FXG3 hydrogel for potential application as new drug delivery system, a single oral dose toxicity study was conducted according to OECD guidelines. Female adult rats of Wistar strain were divided into group A and group B. Group A served as the control and was given 1mL/100 g body weight 0.9% saline. Group B received a dose of 5g/kg body weight of FXG3 hydrogel. Rats were observed continuously for 14 days for clinical signs, and prior to terminal sacrifice, blood samples were taken to assess for haematology and biochemical parameters. Selected organs (heart, liver, lung, kidneys, spleen, and stomach) were removed and examined macroscopically, washed, sliced and stained with haematoxylin-eosin for histopathological investigation. No mortality or any signs of acute toxicity was observed during the observation period. No macroscopic alteration was found in the selected organs. Histopathological examination did not show any pathological changes. Thus, the maximal tolerated dose of FXG3 was calculated to be higher than 5g/kg body weight. It can be concluded that FXG3, a xanthan gum-based hydrogel formulation, was non-toxic after acute oral administration at 5g/kg body weight, and thus may be a promising candidate in controlled drug delivery system.
EN
Hydrogels are a physicochemical system in which an aqueous phase is gelled with a certain gelling polymer. They can make a good alternative to conventional lipophilic or absorption ointment bases, especially if the medicine should be administered to mucosa, because the gelling polymers interact with a mucose what results in mucoadhesion. The use of a hydrogel is preferred to lipophilic ointments in severe inflammations, exudative wounds, acne, oily skin or when the application area on the skin is hairy. Hydrogels also provide a cooling sensation on the skin, when water evaporates and this process is endothermic. Hydrogels are relatively popular also in a compounding practice in other countries, such as USA, where various types of commercially-made hydrogel bases are available. Despite the fact that hydrogels are accepted by law as compounded dosage forms, in Poland they have not been prepared in pharmacies because neither such bases nor suitable polymers are formally registered excipients for drug compounding, and the registration procedure is similar to the one for drug products authorization. The article describes hydrogels as there are first such materials available for pharmacists who are involved in compounding practice. Three gel-forming polymers: methylcellulose, hypromellose and hydroxyethylcellulose and hydrogel bases dedicated for drug compounding are characterized. Several examples of preparations with various active substances are presented and methods of their preparations are proposed. A dermatological base, Celugel, composed of hydroxyethylcellulose and recently registered in Poland for pharmacy compounding is also presented. Special attention is given to methods of hydrogel preparation, depending on the solubility profile of a certain type of polymer. Stability of the compounded hydrogels is discussed, especially regarding microbiological quality and the presence of preservatives. The benefits of these formulations are indicated including a relatively low cost of the hydrogel bases resulting from a low content of the polymers.
PL
Hydrożele dermatologiczne stanowią atrakcyjną alternatywę dla maści na podłożach lipofilowych oraz absorpcyjnych, szczególnie, gdy lek ma być podany na błony śluzowe. Łatwość sporządzenia hydrożelu oraz relatywnie niski koszt to dodatkowe zalety, jednak skomplikowany proces rejestracji polimerów żelujących jako substancji do receptury w Polsce skutkuje brakiem surowców do sporządzania nowoczesnych hydrożeli. Niniejszy artykuł ma na celu przybliżenie postaci hydrożelu w kontekście preparatyki recepturowej w sytuacji, gdy zaczęły być dostępne pierwsze takie surowce.
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