Physicochemical and Quantitative Cell Viability Assays of Quercetin-Encapsulated Alginate Beads

In this thesis, quercetin-encapsulated alginate beads were prepared in two different version; normal ionic cross-linked gel beads and cryogel beads. FT-IR was used to characterize the beads and to check the basic chemical moieties from beads. It was found that quercetin molecules could be trapped into and outside the “egg box” between polymer chains and they would make weak interactions such as polar-polar interactions with the functional groups of alginate. Swelling and drying profiles were studied. Based on release studies, it was found that Mueller Hinton Broth (MHB) was not a suitable release medium for the beads due to the reaction between the ester moiety of casein hydrolysate in MHB and carboxylate groups of alginate would limit the release of quercetin. Therefore, 0.9% saline should be preferred for antimicrobial assays. In addition, sodium ions in RPMI-1640 caused the swelling of beads, which lead to the maximum release of drug. Release kinetic models showed that release of quercetin from cryogel beads fit to the first order release model in DMSO and this meant that release of quercetin is based on the concentration of quercetin. Release of quercetin from gel beads fit to the higuchi release model in DMSO and this meant that quercetin concentration was lower in polymer than its solubility and release occurs through the pores in the matrix. Release of quercetin from gel beads and cryogel beads fit to the first order release model in 0.9% saline with 40% DMSO of total solution. Thus, release of quercetin is based on the concentration of quercetin. Cryogel beads and gel beads fit to zero order release model in RPMI-1640 between 12 and 48 hours. Cell viability, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay showed that as the concentration of quercetin released from the beads increases, the percent viability of (B-CPAP) papillary thyroid cancer cells decreases. In addition, DPPH (2,2-diphenyl-1-picrylhydrazyl) assay showed that as the concentration of quercetin release from beads increases the inhibition of free radical increases. However, in time-kill assay to have signıficant effect on bacteria, the concentration of quercetin in the beads should be increased. Keywords: Quercetin, papillary thyroid cancer cells (B-CPAP) , 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2,2-diphenyl-1- picrylhydrazyl (DPPH)