Preparation of biopolymer structures based on FucoPol

• Autor(a) principal: Fialho, Letícia Maria Rui
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/25833
• topic: FucoPol; gelling capacity; FucoPol gel beads; viability assays; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

FucoPol is a high molecular weight exopolysaccharide (EPS) secreted by the bacterium Enterobacter A47 that is composed of the neutral sugars fucose, galactose and glucose, and the acidic sugar glucuronic acid. It also has substituent acyl groups (acetyl, succinyl and pyruvyl). The presence of glucuronic acid, together with succinyl and pyruvyl, confer the polymer an ani-onic character. The main goal of this thesis was to develop polymeric structures based on FucoPol. First-ly, FucoPol was produced using glycerol as the sole carbon source for the cultivation of Entero-bacter A47. A production of 7.74 g L-1 was reached at the end of 96 h of cultivation. The overall volumetric productivity was 1.97 g L−1 day−1 and the net yield of FucoPol on glycerol was 0.085 g g-1. The produced polymer was extracted from the broth and used to test different gelling pro-cedures. Based on the anionic character of the polymer, different salts of mono-, di- and triva-lent cations were tested (KCl, KNO3, NaCl, NaH2PO4, CaCl2, CaSO4, MgCl2, MgSO4, CuSO4, CuCl2, ZnSO4, ZnCl2, FeSO4, FeCl2, FeCl3) to evaluate the gelling capacity of FucoPol. The gelation of FucoPol occurred in the presence of divalent cations tested excepting calcium salts, at room temperature (25 ºC) in alkaline media (NaOH 2M), while for FeCl3, gels formed only by mixing FucoPol solution with salt aqueous solution at room temperature (25 ºC), with a low pH. Release of copper and/or iron from FucoPol gel beads (FeCl3, CuSO4,) was evaluated in different biological solutions (NaCl (0.9%), SGF, SIF, PBS and DMEM). FucoPol beads tested maintained their shape in NaCl and disintegrated in SGF. CuSO4/FucoPol beads maintained their shape during the assay in PBS, and disintegrated in DMEM and SIF. FeCl3/FucoPol beads became more faint and translucent in DMEM, SIF and PBS while CuSO4/FeCl3/FucoPol beads maintained their shape in these media. The cytotoxicity of FucoPol in different human cell lines (fibroblasts, A2780, A549, HCT116, MCF7) was assessed by MTS assay and results shown that FucoPol was not cytotoxic. Cytotoxicity of FucoPol beads was assessed by Trypan Blue method for K562 cells and results suggest that Fe/FucoPol beads were not cytotoxic, and FucoPol beads prepared with copper af-fect the viability of K562 cells.