diplomsko delo na univerzitetnem študiju Kemijsko inženirstvo
Tadej Žurič (Author), Aleš Ručigaj (Mentor)

Abstract

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.

Keywords

hidrogeli;zamreževanje;poroznost;nabrekanje;učinkovine;sproščanje;pH;temperatura;diplomska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [T. Žurič]
UDC: 544.773.432:615(043.2)
COBISS: 1538536899 Link will open in a new window
Views: 709
Downloads: 270
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Other data

Secondary language: English
Secondary title: Effect of pH value and temperature on controlled drug release from hydrogels
Secondary abstract: 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.
Secondary keywords: hydrogel;pH;temperature;drug;release;
Type (COBISS): Bachelor thesis/paper
Study programme: 1000372
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo
Pages: 28 str.
ID: 11412831