Treatment techniques on biocompatible titanium to modify the surface wetting properties.

The physical properties of biocompatible titanium surfaces were modified using different techniques of surface treatment. Particularly the measurements of roughness and wetting ability were controlled using six different techniques: polishing, sandblasting, acid attack, laser ablation, ion implantation and nanoparticle deposition. The titanium surface wetting can be modified drastically depending on the used treatment to enhance the hydrophilic or the hydrophobic behaviour of the metallic biocompatible surface. The study demonstrates that a linear relation between roughness and contact angle occurs. Possible applications to permanent or removable prosthesis titanium based are presented and discussed.

Wetting ability of biological liquids in presence of metallic nanoparticles.

The wetting ability of water and of some biological liquids was measured on different biocompatible surfaces with and without different colloidal metals. Insoluble nanoparticles disperse in biological tissues enhance some properties, such as the interface adhesion between two surfaces, the X-ray contrast of medical images and the absorbed dose during radiotherapy treatments. The introduction of nanoparticles in the liquids generally improves the wetting ability and changes other properties of the solution, due to the different distribution of the adhesion forces, to the nature, morphology and concentration of the added nanoparticles. An investigation on the contact angle of the liquid drops, physiological liquids, including the human blood, placed on different substrates (polymers, ceramics and metals) with and without the use of metallic nanoparticles is presented, evaluated and discussed.

How do wettability, zeta potential and hydroxylation degree affect the biological response of biomaterials?

It is well known that composition, electric charge, wettability and roughness of implant surfaces have great influence on their interaction with the biological fluids and tissues, but systematic studies of different materials in the same experimental conditions are still lacking in the scientific literature. The aim of this research is to investigate the correlations between some surface characteristics (wettability, zeta potential and hydroxylation degree) and the biological response (protein adsorption, blood wettability, cell and bacterial adhesion) to some model biomaterials. The resulting knowledge can be applied for the development of future innovative surfaces for implantable biomaterials. Roughness was not considered as a variable because it is a widely explored feature: smooth surfaces prepared by a controlled protocol were compared in order to have no roughness effects. Three oxides (ZrO2, Al2O3, SiO2), three metals (316LSS steel, Ti, Nb) and two polymers (corona treated polystyrene for cell culture and untreated polystyrene for bacteria culture), widely used for biomedical applications, were considered. The surfaces were characterized by contact profilometry, SEM-EDS, XPS, FTIR, zeta potential and wettability with different fluids. Protein adsorption, blood wettability, bacterial and cell adhesion were evaluated in order to investigate the correlations between the surface physiochemical properties and biological responses. From a methodological standpoint, XPS and electrokinetic measurements emerged as the more suitable techniques respectively for the evaluation of hydroxylation degree and surface charge/isoelectric point. Moreover, determination of wettability by blood appeared a specific and crucial test, the results of which are not easily predictable by using other type of tests. Hydroxylation degree resulted correlated to the wettability by water, but not directly to surface charge. Wetting tests with different media showed the possibility to highlight some differences among look-alike materials. A dependence of protein absorption on hydroxylation degree, charge and wettability was evidenced and its maximum was registered for surfaces with low wettability in both water based and protein containing media and a moderate surface charge. As far as bacterial adhesion is concerned, no effect of surface charge or protein adsorption was evidenced, while the presence of a high acid component of the surface energy appeared significant. Finally, the combination of hydroxylation degree, wettability, surface charge and energy (polar component) emerged as a key parameter for cell adhesion and viability.

Bromocriptine treatment of nonfluent aphasia.

Using a double-blind, placebo-controlled, crossover design, we studied the effect of bromocriptine (15 mg daily) in 20 men with chronic nonfluent aphasia. The study was conducted over a 28-week period in two phases. In phase I, the patients received either bromocriptine or placebo; in phase II the treatments were crossed over. We evaluated each patient's language and nonverbal cognitive skills at the beginning and end of each phase and 6 weeks after completion of phase II. When compared with placebo treatment, bromocriptine did not significantly improve the patient's speech fluency, language content, overall degree of aphasia severity, or nonverbal cognitive abilities. Based on these results, bromocriptine is not recommended as monotherapy for the treatment of chronic nonfluent aphasia.