Papers by Author: A.C. Queiroz

Abstract: Biocompatibility has long been associated with surface microtopography, microtexture and microchemistry. The surface topography ultimately affects the nature and the strength of the interactions that occur at biomaterial-biological environment (cell adhesion, mobility, spreading and proliferation). Thus, it is necessary to produce and work with controlled microtopographical surfaces that present reproducible microdomains of a dimension similar to that of the biological elements of interest (for instance, cells). [1] There are a number of substrates that already have been studied (such as silicone, polystyrene, poly-L-lactic acid and titanium coated polystyrene) in terms of surface topography. [2] However, few studies are related to hydroxyapatite substrates. As it is well established, hydroxyapatite is a well known ceramic that is extremely used in medical applications, namely implants and coatings. In this work, the surface topography of dense hydroxyapatite substrates was altered by using KFr excimer laser. Excimer lasers produce high-intensity, pulsed ultraviolet radiation and are especially well suited for materials processing due to their large beam cross-section area, which permits using mask projection technologies to process relatively large areas in a single step.[3]

Abstract: Dense and porous hydroxyapatite materials aimed at being used in controlled drug delivery, were characterised and studied in order to evaluate their ability to adsorb and release sodium ampicillin in a controlled manner, as a model for a drug delivery system, potentially applicable associated to surgery for the treatment of bone defects. These porous materials should also have adequate mechanical strength to withstand manipulation and sculpturing in surgery room. Adsorption and release profiles were obtained for a range of porous materials, leading to higher adsorption rates and more adequate release profiles than for dense materials.

Abstract: The adsorption behaviour of sodium ampicillin to dense and porous hydroxyapatite as been extensively studied through the obtention of an adsorption isotherm. This isotherm was produced at body temperature, and a wide range of antibiotic solutions was used. The adsorption behaviour was measured by UV spectroscopy. The shape of the isotherm for the two forms of the material, dense and porous, indicates that the adsorption behaviour of the antibiotic seems to be different; however, this is due to the adsorption taking place within the pores of the porous material, thus showing a larger amount of antibiotic adsorbed.