Fabricação e caracterização de scaffolds compósitos de polímero-hidroxiapatite e polímero-videro para engenharia de tecidos

Abstract

Tissue engineering has adopted different strategies, with the aim of finding solutions that allow the improvement of the ex-vivo conditions that mimic the regeneration of tissues. One of the most recent strategies consist in the development of three dimensional porous structures that serve as temporary supports for the seeding of cells, allowing their adhesion, proliferation and extracellular matrix production, leading to the formation of new tissue. In this work two types of composite scaffolds with potential applications in tissue engineering were prepared the scaffolds. In one of poly (L-lactic acid) (PLLA) was used as matrix and hydroxyapatite (HAp) as inorganic filler and in another poly (L-lactic acid) served as matrix and a bioactive glass (T14P43) as inorganic filler. PLLA was chosen because it is a biodegradable synthetic polymer, biocompatible and piezoelectric, a feature also identified in bone tissue. The choice of the filling phases, a bioactive glass or hydroxyapatite, was due to the fact that hydroxyapatite exhibit osteoconductive capacity and has a high biocompatibility and the bioactive glass has bioactive characteristics appropriate for application in contact with bone tissue. The process used to manufacture the scaffold was based on a thermally induced phase separation technique (TIPS) of solutions of 5,5 or 6,5 % (w/w) PLLA/dioxane/water with hydroxyapatite and PLLA/dioxane/water with bioactive glass, varying the following parameters: content of hydroxyapatite (0%, 30% and 50% (m/m)) and bioactive glass (0% and 30% (m/m)), temperature of mixture (75 and 80ºC), time of mixing (15 and 90 minutes) and time for phase separation (10 and 60 minutes). The morphology of the scaffolds was evaluated by scanning electron microscopy (SEM), the bioactive potential of the composites was tested by immersion in synthetic fluid (SBF: simulated body fluid), for periods to 24 days and the mechanical properties were determined by compression testing. Scaffolds with different morphology in were obtained depending on the hydroxyapatite, content with pore size decreasing with the addition of hydroxyapatite. Scaffolds prepared with glass as filler presented pore sizes higher than those containing hydroxyapatite. No bioactive behavior was found in both types of scaffolds when immersed in SBF. This fact, together with the measured mechanical properties suggest that the porous structures developed in this work may have applications in tissue engineering strategies preferably ex-vivo, namely as temporary support for cells.

Date of Award	2014
Original language	Portuguese
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Maria Helena Figueira Vaz Fernandes (Supervisor)