title: Enzyme-functionalized biomimetic apatites: concept and perspectives in view of innovative medical approaches.
abstract: Biomimetic nanocrystalline calcium-deficient apatite compounds are particularly attractive for the setup of bioactive bone-repair scaffolds due to their high similarity to bone mineral in terms of chemical composition, structural and substructural features. As such, along with the increasingly appealing development of moderate temperature engineered routes for sample processing, they have widened the armamentarium of orthopedic and maxillofacial surgeons in the field of bone tissue engineering. This was made possible by exploiting the exceptional surface reactivity of biomimetic apatite nanocrystals, capable of easily exchanging ions or adsorbing (bio)molecules, thus leading to highly-versatile drug delivery systems. In this contribution we focus on the preparation of hybrid materials combining biomimetic nanocrystalline apatites and enzymes (lysozyme and subtilisin). This paper reports physico-chemical data as well as cytotoxicity evaluations towards Cal-72 osteoblast-like cells and finally antimicrobial assessments towards selected strains of interest in bone surgery. Biomimetic apatite/enzyme hybrids could be prepared in varying buffers. They were found to be non-cytotoxic toward osteoblastic cells and the enzymes retained their biological activity (e.g. bond cleavage or antibacterial properties) despite the immobilization and drying processes. Release properties were also examined. Beyond these illustrative examples, the concept of biomimetic apatites functionalized with enzymes is thus shown to be useable in practice, e.g. for antimicrobial purposes, thus widening possible therapeutic perspectives.
authors.affiliation: Fraunhofer IGB Institute, Nobelstraße 12, 70569, Stuttgart, Germany.
authors.forename: Christina G
authors.initials: CG
authors.lastname: Weber
authors.forename: Michaela
authors.initials: M
authors.lastname: Mueller
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vandecandelaere
authors.forename: Iris
authors.initials: I
authors.lastname: Trick
authors.forename: Anke
authors.initials: A
authors.lastname: Burger-Kentischer
authors.forename: Tanja
authors.initials: T
authors.lastname: Maucher
authors.forename: Christophe
authors.initials: C
authors.lastname: Drouet
mesh_terms: D001031:Apatites / Q000737:chemistry*; D018407:Bacterial Physiological Phenomena / Q000187:drug effects*; D040761:Biomimetic Materials / Q000138:chemical synthesis*; D018786:Bone Substitutes / Q000138:chemical synthesis; D002130:Calcium Phosphates / Q000737:chemistry*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation; D004795:Enzyme Stability; D006801:Humans; D008422:Materials Testing; D008968:Molecular Conformation; D009113:Muramidase / Q000737:chemistry*; D049329:Nanostructures; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D010316:Particle Size; D020860:Subtilisin / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D001031:Apatites; D018786:Bone Substitutes; D002130:Calcium Phosphates; C020243:calcium phosphate; D009113:Muramidase; D020860:Subtilisin