MATERIALS BASED ON BIOMACROMOLECULES AND INORGANIC COMPOUNDS:CALCITE BASED BUILDING MATERIALS AND IRON OXIDE NANOPARTICLES

Abstract The present project has been developed on two distinct lines of work related to the use of biomacromolecules, in particular polysaccharides, to give special purpose hybrid materials. The first is related to preparation of calcite based materials that can potentially replace cement, the second concerns the synthesis of iron oxide nanoparticles for biomedical applications. I) Calcite-based biocomposite material with special mechanical properties The production of building materials is essentially related to cement production. Although cement is a material characterized by the ability to quickly hydrate and to convert into a highly mechanical stress and weather agent resistant material, its production is very ancient and polluting. In fact, the raw material consists of cement minerals which are treated at very high temperatures (1450 °C) with consequent development of CO2 which is a widely diffused greenhouse gas. Moreover, heat treatment is very expensive in terms of electricity and fossil fuel consumption. For these reasons the development of new building materials, involving mild condition chemical processes and renewable raw materials, is highly desirable for human development. Object of this investigation is the innovative preparation and evaluation of materials based on calcium carbonate and biopolymers as alternative to cement. In this formulation calcium carbonate will be used without any heat treatment, avoiding the energy demanding and pollutant decarboxylation process. Our purpose is to find a formulation in which a natural polymer, interacting with calcium carbonate granules induces a mechanical reinforcement in the composite material, that will be measured by mechanical compression stresses. The work consisted in finding the right ingredients of the formulation, which should have a consistency similar to that of mortar. A number of polysaccharides, anionic and neutral, were tested for their capacity to interact with calcite lattice. In particular carboxylated polysaccharides with high density charge such as: carboxymethylcellulose with substitution degree (DS) 2, sodium alginate, and chondroitin sulfate, were chosen. Interestingly chondroitin sulfate resulted as promising agent in improving the mechanical properties of calcium carbonate based material, in addition this hybrid material was able to raise the mechanical resistance of a concrete. 4 II) Biomacromolecules coated iron oxide nanoparticles: synthesis and properties In the first year of PhD course I’ve worked on hybrid materials for biomedical application: nanoparticles are nowadays a new important object of studies of medicinal chemistry and different scientists collaborate in order to mix their skills: biologists, engineers , and chemists. The goal was to synthesize nanoparticles with an appropriate size for the human tissue and with small size dispersion, with a shell made by two components biological matrix: a polysaccharide and a protein, these should ensure tissue biocompatibility and biological activity. In detail, the aim of the project is to prepare bovine serum albumin (BSA) and hyaluronic acid (HA) coated SPIONs (BSA-HA@Fe3O4), to characterize them, load them with drugs and chemosensitizers; the hybrid nanoparticles will be evaluated in their performance in selective drug delivery for cancer cells, and in diagnostic localization of tumors in vivo. The adduct between nanoparticles composed by magnetite (Fe3O4) or maghemite (γ-Fe2O3) and biomacromolecules, hyaluronic acid (HA) and albumin (BSA), were obtained using dopamine (DA) to covalently bind these macromolecules to the surface of the nanoparticle iron oxide core. The prepared product is an iron oxide nanoparticle surrounded by HA and BSA macromolecules as ligands, which act stabilizing the superstructure, anti-cancer targeting and drug delivery.