Diffusion of curcumin and other small molecules into alginate hydrogels

Omladič, Lucija (author), Osojnik Črnivec, Ilja Gasan (mentor), Andre Vicente, Filipa Aleksandra (comentor)

Hydrogels are widely applied for the entrapment and controlled diffusion of small molecules due to their tunable structure and responsiveness to environmental conditions. This study investigated the diffusion behavior of curcumin and selected low-molecular weight compounds – ethanol, lactic acid, glucose and vanillin in alginate hydrogels, with particular emphasis on the effects of hydrogel composition, ethanol exposure and cyclodextrin incorporation. Diffusion experiments were performed using different varying hydrogel compositions exposed to different environmental conditions. Curcumin was monitored by ultraviolet–visible spectrometry and evaluated using similarity factor analysis, while diffusion of ethanol, lactic acid, glucose and vanillin was determined using high-performance liquid chromatography and ion chromatography. The results showed that increasing alginate concentrations reduced diffusion efficiency due to higher network density. Exposure to ethanol caused hydrogel shrinkage. Incorporation of cyclodextrins generally increased curcumin diffusion, which was attributed to the formation of inclusion complexes that improved apparent solubility. The extent of this effect depended on cyclodextrin type and concentration, with β-cyclodextrin exhibiting the most pronounced concentration-dependent influence. In contrast, glucose and ethanol diffusion were largely unaffected by cyclodextrins, while vanillin and lactic acid showed reduced diffusion in their presence. These findings demonstrate the potential of alginate hydrogels with cyclodextrin inclusion for controlled diffusion and selective retention of bioactive compounds in food bioprocessing application.

• Language: English
• Keywords: hydrogels, alginate, curcumin, cyclodextrins, food metabolites, diffusion
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [L. Omladič]
• Year: 2026
• PID: 20.500.12556/RUL-181496
• UDC: 664.0:544.773.432
• COBISS.SI-ID: 274928643
• Publication date in RUL: 09.04.2026

Secondary language

• Language: Slovenian
• Title: Difuzija kurkumina in drugih malih molekul v alginatne hidrogele

Abstract

Hidrogeli se zaradi svoje prilagodljive strukture in sposobnosti odzivanja na okoljske dejavnike pogosto uporabljajo za zamreženje in nadzorovano sproščanje malih molekul. V raziskavi smo preučevali difuzivnost kurkumina ter izbranih nizkomolekularnih spojin – etanola, mlečne kisline, glukoze in vanilina v alginatne hidrogele, pri čemer smo se osredotočili na vpliv sestave hidrogela, prisotnosti etanola in dodatka ciklodekstrinov. Difuzijske poskuse smo izvedli pri različnih sestavah hidrogelov in pod različnimi okoljskimi pogoji. Difuzivnost kurkumina smo spremljali z ultravijolično-vidno spektrometrijo in ovrednotili z dejavnikom podobnosti, medtem ko smo difuzivnost ostalih spojin določili z visokozmogljivo tekočinsko in ionsko kromatografijo. Ugotovili smo, da večja koncentracija alginata zmanjša difuzijsko učinkovitost zaradi večje gostote polimerne mreže. Izpostavljenost etanolu je povzročila krčenje hidrogela. Dodatek ciklodekstrinov je na splošno povečal difuzivnost kurkumina, kar je povezano s tvorbo inkluzijskih kompleksov, ki izboljšajo njegovo navidezno topnost. Učinek je bil odvisen od vrste in koncentracije ciklodekstrina, pri čemer je β-ciklodekstrin izkazal najizrazitejši vpliv. Nasprotno difuzivnost glukoze in etanola v prisotnosti ciklodekstrinov ni bila bistveno spremenjena, medtem ko sta imela vanilin in mlečna kislina zmanjšano difuzivnost. Rezultati potrjujejo potencial alginatnih hidrogelov z vključitvijo ciklodekstrinov za nadzorovano difuzijo in selektivno zadrževanje bioaktivnih spojin v živilsko-bioprocesnih aplikacijah.

• Keywords: hidrogeli, alginat, kurkumin, ciklodekstrini, živilski metaboliti, difuzija