Surface functionalization of bioactive glasses with natural molecules of biological significance

Natural or artificial materials used for replacement or supplement the functions of living tissues, termed as biomaterials, may be bioinert (i.e. alumina and zorconia,) resorbable (i.e. tricalcium phosphate), bioactive (i.e. hydroxyapatite, bioactive glasses, and glass-ceramics) or porous for tissue ingrowth (i.e. hydroxyapatite-coated metals). Among all the biomaterials, bioactive glass and glass-ceramics are widely used in orthopedic and dental applications and are being developed for tissue engineering. However, to a large extent, the behavior and overall performance of biomaterials are governed by surface properties. Surface modifications therefore provide unique possibilities to control the subsequent surface interaction and response which are required for particular application. By tailoring the material surface, a wide portfolio of additional functionalities is enabled to overcome material deficiencies while maintaining its bulk material properties. As a consequence, the surface functionalization of materials has become pivotal for academic research as well as industrial product development. Plant-derived polyphenols are compounds possessing one or more aromatic rings with one or more hydroxyl groups. They are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants, with more than 8,000 phenolic structures currently known, ranging from simple molecules such as phenolic acids to highly polymerized substances such as tannins. Numerous researches and investigation reported the notable biological activities of polyphenol, such as cardiovascular protection, cancer prevention and treatment, antiaging activity as well as applications in Alzheimer’s disease, oral health, immune function diabetes and other neurodegenerative disorders. Till now, a number of previous investigations provide a number of surface functionalization techniques and make it possible to graft various kinds of biomolecules such as proteins, growth factors and enzymes to the surface of bioactive glass and glass-ceramics. However, very few researches have been focused on the coupling of natural bioactive polyphenols on surface of bioactive glass and glass-ceramics. As a conclusion, the aim of this thesis is to combine bioactive glasses and glass-ceramics with natural polyphenols, in this case they are grape polyphenol and tea polyphenol extracted from grape skin and green tea respectively, in order to make it possible to immobilize biomolecules as well as prepare smart biomaterials with both typical inorganic activity and specific biological benefits from natural molecule. This thesis can be divided into five chapters. The first chapter introduces the composition, chemical structure, biological properties and potential applications of plant polyphenols. In chapter II, the extraction methods and analysis techniques involved in polyphenol investigation are reviewed. Chapter III mainly illustrated the structure, property and biomedical application of biomaterials as well as methodologies and evaluation of surface functionalization. Materials and techniques related to this thesis are demonstrated in chapter IV. The last chapter, also the core chapter of this thesis, describes the results and discussions in five separate sections: i) surface functionalization of SCNA and CEL2 with gallic acid; ii) surface functionalization of SCNA and CEL2 with polyphenol extracted from grape skin; iii) surface functionalization of SCNA and CEL2 with polyphenol extracted from green tea; iv) surface functionalization of SC-45 with gallic acid and buffered gallic acid and v) surface functionalization of SC-45 with folic acid.