20.500.12556/RUL-114246 Vpliv pH vrednosti in temperature na kontrolirano sproščanje učinkovin iz hidrogelov Effect of pH value and temperature on controlled drug release from hydrogels Hidrogeli imajo v primerjavi z ostalimi biomateriali boljšo biokompatibilnost in mehanske lastnosti, nastavljivo biorazgradljivost ter večjo poroznost. Ker so v veliki meri tudi nestrupeni, nekatere njihove fizikalne lastnosti pa so na las podobne lastnostim zunajceličnega matriksa živih tkiv, se hidrogeli uporabljajo v biomedicinskih in farmacevtskih aplikacijah. Pametni hidrogeli so posebna vrsta hidrogelov, ki se odzivajo na različne dražljaje iz okolja, med drugim tudi na pH vrednost in temperaturo. Omenjena dražljaja sta v telesu prisotna naravno, zato je možno pH odzivne in temperaturno odzivne hidrogele uporabiti za sproščanje oziroma dostavo učinkovin. pH občutljivi hidrogeli izrabljajo dejstvo, da se pH vrednost na mnogih mestih v telesu razlikuje. Prav tako so za biomedicinske aplikacije primerni temperaturno odzivni hidrogeli, saj pri velikem deležu takšnih hidrogelov opazimo oblikovanje gela pri fiziološki temperaturi 37 °C. Hidrogeli se na dražljaje odzovejo bodisi s spremembo v stopnji nabrekanja, strukturi polimerne mreže, permeabilnosti ali trdnosti. Sproščanje učinkovin poteka v neposredni povezavi z nabrekanjem hidrogela. Ko voda prodre v hidrogel, polimer nabrekne, sočasno pa raztopljena učinkovina prehaja skozi nabreknjeno strukturo hidrogela v zunanji medij. Difuzija v hidrogelu lahko poteka bodisi preko koncentracijskega gradienta ali polimerne relaksacije. Če difuzija poteka zaradi koncentracijskih razlik, je prehajanje snovi opisljivo s Fickovim zakonom. V kolikor pa je vzrok relaksacija polimerov, potem pride do anomalne difuzije. Case-II transport je ekstremni primer takšne difuzije in je definiran glede na mejo med elastičnim in steklastim področjem v hidrogelu. Zanimiv je predvsem, ker je zanj značilen ničti red kinetike sprostitve. In comparison to other biomaterials, hydrogels have better biocompatibility and mechanical properties, tuneable biodegradability and higher porosity. In most cases hydrogels are also non-toxic, and since some of their physical properties resemble the properties of the extracellular matrix of living tissues hydrogels are used in biomedical and pharmaceutical applications. Smart hydrogels are a special type of hydrogels that are able to respond to stimuli from the environment, such as pH value and temperature. Both of these stimuli are naturally present in the human body, hence pH-responsive and thermoresponsive hydrogels make a good case for drug delivery. There are many variations of pH value in the body, which makes pH-sensitive hydrogels good candidates for drug release. Since a great deal of thermosensitive hydrogels exhibit gelation at the physiological temperature of 37 °C, they are very suitable for biomedical applications as well. Hydrogels respond to stimuli via change of degree of swelling, polymer network structure, permeability or mechanical strength. Drug release is directly connected to hydrogel swelling. When water penetrates into the hydrogel, polymer swells. Simultaneously the dissolved drug diffuses through the swollen hydrogel structure into the exterior medium. Diffusion in hydrogel is either driven by concentration gradient or polymer relaxation. Former can be expressed by Fick's law, whereas in the latter case anomalous diffusion takes place. Case-II transport is an extreme case of anomalous diffusion and it's defined by the boundary between rubbery and glassy state in the hydrogel. Case-II transport is especially interesting since it exhibits zero order release kinetics. hidrogel pH temperatura učinkovina sproščanje hydrogel pH temperature drug release true false false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2020-02-20 15:05:02 2020-02-20 15:05:13 2022-08-26 03:49:57 0000-00-00 00:00:00 2020 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 6141 1538536899 Zuric_Tadej_-_Vpliv_pH_vrednosti_in_temperature_na_kontrolirano_sproscanje_ucinkovin_iz_hidrogel.pdf Zuric_Tadej_-_Vpliv_pH_vrednosti_in_temperature_na_kontrolirano_sproscanje_ucinkovin_iz_hidrogel.pdf 1 A88EE6258B4ECD344D2E6B5B6BAA6DD2 5db6ee8ceb7c189c8087ada34f2d0916cbe6ca6cbb50474f484e5570b07c8b76 322aacb4-a1b8-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=126398 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0