Preparação e caraterização de scaffolds de colagénio-nanohidroxiapatite modificados com o-phospho-L-serine para a regeneração tecidular óssea

Abstract

In order to mantain a healthy skeleton, bone tissue is constantly subjected to dynamic and physiological processes of reabsorption and new bone formation. Usually, the process of bone healing is triggered in some cases of tissue fragility or tissue damaged like e.g. large defects. In other way, sometimes the healing process does not respond approprieately. Fortunately, bone tissue engineering offers new therapeutic strategies to aid in the muscoskeletal healing. The development and use of biomaterials or biomimetic materials that can replace autologous grafts, recognized as gold standard, are often used today in daily clinical practice. Besides increased the range of choice, these biomaterials also have improved the clinical treatment. Nonetheless, the ideal material for bone regeneration requires further investigation. This material must have the same characteristics that we find in the native bone such osteointegration, osteoinduction and osteogenisis properties. This dissertation try to investigate and expose the physicochemical and mechanical properties of collagen/nano-hydroxyapatite biocomposites scaffolds modified with O-phospho-L-serine (phosphoserine), obtained by cryogelation method, as potential bone substitutes. Morphology and surface analysis was performed using Scanning Eletron Microscope (SEM) and revealed that all cryogel scaffolds had highly porous structure with interconnective porosity with the presence of nanometric crystals of hydroxyapatite. According to the chemical analysis through Fourier Transform Infrared Spectroscopy (FT-IR), the peaks of collagen and hydroxyapatite in the biocomposite scaffolds are coincident with the values reported in the literature and the phosphoserine do not interfer with the link between collagen molecules and hydroxyapatite aggregates. The swelling tests has been shown that different concentrations of the aminoacid in study, have influence in water uptake, i.e., collagen/nano-hydroxyapatite biocomposites scaffolds with high content of phosphoserine display higher water uptake than low phosphoserine content. On the other hand, when the samples are in PBS (phosphate buffer), the samples with phosphoserine show lower degree of swelling behavior. Finally, in agreement with Dynamic Mechanical Analysis (DMA), the samples with phosphoserine show lower mechanical properties, but no significantly, even as visco-elastic properties have changed and reveals samples deformation. The results of this investigation allow to assert that collagen/nano-hydroxyapatite biocomposite scaffolds modified with phosphoserine exhibit advantgeous physicochemical and mechanical properties for in vitro studies.

Date of Award	26 Jul 2016
Original language	Portuguese
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Christiane Laranjo Salgado (Supervisor) & Filipe Miguel Araújo (Co-Supervisor)