My thesis work focuses on the study of biocompatibility, bioactive and structural properties of mesoporous bioglasses. They are obtained via sol-gel, by evaporation-induced self assembly method (EISA) using Pluronic® P-123 as a surfactant to induce ordered porosity.
In my first period of thesis I have synthesized four Mesoporous Bioactive Glasses (named hereafter MBG), as described in Ref. , with different amount of CeO2. Tetraethyl ortosilicate (TEOS), calcium nitrate tetrahydrate, triethyl phosphate (TEP) and cerium nitrate hexahydrate are used as sources of SiO2, CaO, P2O5 and CeO2, respectively.
The use of cerium is related to his proved ability to catalyze the decomposition of hydrogen peroxide (H2O2) into water and oxygen, due to the equilibrium Ce3+/Ce4+, mimicking the catalase enzyme action. The role of the latter is very important, since it protects cells from oxidative stress caused by reactive oxygen species (ROS), .
Subsequently I have modified those glasses by forming hydrogel’s spheres of alginate (ionic cross-linking method), called beads: the glasses were milled and sieved at a mean dimension lower than 250 μm and incorporated into alginate beads.
Alginate hydrogels are proving to have a wide applicability as biomaterials. They have been used as scaffolds for tissue engineering, as delivery vehicles for drugs, and as model extracellular matrices for basic biological studies.
The results obtained on bioglasses, from previous in vitro biocompatibility studies, weren’t positive and it’s thought to be due to the rapid dissolution of the glasses’ powders that causes a pH increase, creating an unfavorable environment for our cells. On the other hand, alginate-based samples demonstrate a greater interaction between alginate and calcium ions on the glass surface that reduces the release of calcium ions to the solution and the exchange with the H+ ions, so reducing pH increase.
For this reason in my work thesis I will focus the attention on hydrogel alginate spheres loaded with glass powder in order to evaluate if their biocompatibility can be better than “classic” bioglass.
In collaboration with GRUPO DE INVESTIGACION BIOMATERIALES INTELIGENTES (Department of Inorganic and Bioinorganic Chemistry, Faculty of Pharmacy, Universidad Complutense de Madrid) I will continue my research period doing the following activities:
in vitro biocompatibility tests (beads) using pre-osteoblasts cell line (MC3T3-E1), also inducing oxidative stress with hydrogen peroxide
SSA (specific surface area-BET) with N2 absorption of bioglasses and beads in order to evaluate the behaviour of superficial properties before and after powder’s incorporation
SAXS (small angle X-ray scattering) to show the presence of peaks characteristic of mesoporous ordinate structure
SEM, TEM to gather information about porosity of powders and the morfology’s change after their inclusion into beads
bioactivity tests in SBF (powders and beads); after tests FTIR, SEM and TEM characterization to evaluate the morfology and the glass surface evolution (beads).