Mesoporous silica nanoparticles coatings on titanium substrates

Bones can suffer from damages due to ageing or traumatisms like fractures. When they are too damaged or if the fracture is too important, bones often need an exterior help to recover: the implants. The ideal implant maintains bone parts together and could promote bone regeneration and osseointegration. However, after placing the implant into the body, bone healing and regeneration sometimes don’t work through properly. Indeed, the current bone implants sometimes lead to failure especially with patients suffering from diabetes mellitus (DM). In fact, it has been shown that DM is linked to the phenomenon called oxidative stress. The latter induces an accumulation of reactive oxygen species (ROS) which can cause dysfunction of the bone regenerating cells, the osteoblasts. Titanium and its alloys are a well-known for their performances as biomaterials. The idea to prevent the implantation failure is to develop new functionalized implants. These implants must act like drug-carrier and be able to release the appropriate amount of drug locally. Many studies proposed different coatings for titanium that can be loaded with active principle. Among such coatings, the mesoporous silica nanoparticles (MSN) may be an efficient drug-carrying coating for titanium implants. The other coating techniques that have been studied involved weak bonds. However, the ideal coating needs to be bound strongly enough to remain stable on the titanium surface. Thus, the coating technique is a crucial parameter to obtain the ideal MSN coating. This project aimed to develop MSN coating on titanium substrate. The process chosen for such coating was based on the silanization reaction. Silanized titanium substrates would react with functionalized MSN. This kind of reaction would induce the covalent bonding that is required between the nanoparticles and the titanium substrate to provide the right mechanical strength for the coating. In this study, titanium substrate silanization process has been reviewed to be enhanced. Different conditions and parameters were tested: the activation technique, the coating time, the MSN coating solution concentration and two different silanes. The first trials were at first realized with the 3-(Triethoxysilyl)propyl isocyanate (ICPTES) as the silane precursor. Then the reaction was studied with 3-(Triethoxysilyl)propyl isocyanate (TESPSA). For each silane precursors, three activation techniques were tried: UV activation, NaOH solution attack and dioxygen plasma. In addition, ultrasound device was used to check the coating stability of the samples. Each sample was controlled using the scanning electron microscopy (SEM) to study MSN coating morphology on the titanium plates. The best coating was obtained with an overnight coating reaction using TESPSA (2%, v/v), the MSN solution concentration was 5 g/L and the titanium sample was activated with dioxygen plasma