Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em BiotecnologiaThe aims of this work were the functionalization of magnetic nanoparticles (MNPs)with Gum Arabic (GA) and the study of the effect of these modified particles on the
growth and survival of mammalian cell cultures. MNPs consisting of Fe3O4 were
synthesized by the Massart Method and further functionalized with GA by adsorption
and covalent coupling via GA amino or carboxylic acid groups. The GA adsorption and
binding isotherms displayed a Langmuir type. The maximum of GA coated on MNPs followed the order MNP_GAAPTS < MNP_GA_GAADS < MNP_GAADS < MNP_GAEDC,where MNPs coated with GA via EDC activation gave the best result for coupling (2,80g GA bound/g MNP for 2,62 mg/ml GA (eq.)). The particles were characterized by FTIR, BET, TEM and DLS, showing the greater dispersion and colloidal stability of particles in aqueous solution when GA is present. Cultures of mammalian cell lines(HEK293, CHO and TE671) were grown in the presence of uncoated and GA coated
MNPs. Cellular viability was assessed for different incubation periods by means of the
Trypan Blue exclusion test and by comparing cellular density with that of cells grown in
the absence of particles. Different MNPs need different incubation periods to deposit at cellular surface, and the results vary with the cell type tested. With HEK293 cells,
MNP_GAAPTS attach to the cell surface after only 30 minutes, while bare magnetite and
MNP_GAEDC have a greater effect on compromising cellular viability. On the other
hand, MNP_GAADS needed longer incubation periods to attach to the cell surface and
caused less cellular damage for identical incubation times with the other particles tested
