Adhesion and proliferation of HeLa and fibroblast cells on chemically-modified gold surfaces.

The development of materials that allow proper functioning of cells on solid supports is directly relevant to the construction of living-cell biosensors. Both physical and chemical properties of the surfaces have been shown to be critical in this field. Our aim is to report correlations between chemical properties of surfaces and cell behavior by studying adhesion, viability and proliferation of fibroblasts and HeLa cells. Neither fibroblasts nor HeLa cells adhered to a hydrophobic surface. Fibroblasts were able to attach and proliferate well on all other surfaces tested. In contrast, on some surfaces where HeLa cells adhered and were viable, proliferation decreased by half while on others proliferation was not affected. Proliferation was significantly correlated with the level of adsorption of serum proteins on the surface (quantified by surface plasmon resonance), but not with surface wettability (water contact angle). Interestingly, surfaces modified with COOH and HSO3 groups were the ones that favored most protein adsorption and allowed the best measures for HeLa cell proliferation. The decrease of HeLa cell proliferation on surfaces covered with poly-L-lysine (PL) was related with the profile of integrin expression. Compared to a polystyrene control surface, there was an increase in αV and αVß3 and a decrease in α2 and α3, indicating that migration rather than proliferation could be favored on PL functionalized surfaces. These results indicate that charge is more important than wettability to determine biocompatibility.

Search for cytotoxic agents in multiple Laurencia complex seaweed species (Ceramiales, Rhodophyta) harvested from the Atlantic Ocean with emphasis on the Brazilian State of Espírito Santo

The development of new anti-cancer drugs of algal origin represents one of the least explored frontiers in medicinal chemistry. In this regard, the diversity of micro- and macroalgae found in Brazilian coastal waters can be viewed as a largely untapped natural resource. In this report, we describe a comparative study on the cytotoxic properties of extracts obtained from the Laurencia complex: Laurencia aldingensis, L. catarinensis, L. dendroidea, L. intricata, L. translucida, L. sp, and Palisada flagellifera. All of these species were collected in the coastal waters of the State of Espírito Santo, Brazil. Four out of the twelve samples initially investigated were found to show significant levels of toxicity towards a model tumor cell line (human uterine sarcoma, MES-SA). The highest levels of cytotoxicity were typically associated with non-polar (hexane) algal extracts, while the lowest levels of cytotoxicity were found with the corresponding polar (methanol) extracts. In this report, we also describe a biological model currently in development that will not only facilitate the search for new anti-cancer drug candidates of algal origin, but also permit the identification of compounds capable of inducing the destruction of multi-drug resistant tumors with greater efficiency than the pharmaceuticals currently in clinical use.