title: Direct Covalent Grafting of Phytate to Titanium Surfaces through Ti-O-P Bonding Shows Bone Stimulating Surface Properties and Decreased Bacterial Adhesion.
abstract: Myo-inositol hexaphosphate, also called phytic acid or phytate (IP6), is a natural molecule abundant in vegetable seeds and legumes. Among other functions, IP6 inhibits bone resorption. It is adsorbed on the surface of hydroxyapatite, inhibiting its dissolution and decreasing the progressive loss of bone mass. We present here a method to directly functionalize Ti surfaces covalently with IP6, without using a cross-linker molecule, through the reaction of the phosphate groups of IP6 with the TiO2 layer of Ti substrates. The grafting reaction consisted of an immersion in an IP6 solution to allow the physisorption of the molecules onto the substrate, followed by a heating step to obtain its chemisorption, in an adaptation of the T-Bag method. The reaction was highly dependent on the IP6 solution pH, only achieving a covalent Ti-O-P bond at pH 0. We evaluated two acidic pretreatments of the Ti surface, to increase its hydroxylic content, HNO3 30% and HF 0.2%. The structure of the coated surfaces was characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and ellipsometry. The stability of the IP6 coating after three months of storage and after sterilization with γ-irradiation was also determined. Then, we evaluated the biological effect of Ti-IP6 surfaces in vitro on MC3T3-E1 osteoblastic cells, showing an osteogenic effect. Finally, the effect of the surfaces on the adhesion and biofilm viability of oral microorganisms S. mutans and S. sanguinis was also studied, and we found that Ti-IP6 surfaces decreased the adhesion of S. sanguinis. A surface that actively improves osseointegration while decreasing the bacterial adhesion could be suitable for use in bone implants.
authors.affiliation: Group of Cell Therapy and Tissue Engineering, Research Institute on Health Sciences (IUNICS), University of Balearic Islands , Ctra. Valldemossa km 7.5, 07122 Palma de Mallorca, Spain.|Instituto de Investigación Sanitaria de Palma , 07010 Palma, España.
authors.forename: Alba
authors.initials: A
authors.lastname: Córdoba
authors.affiliation: Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Extremadura , Badajoz, Spain.|Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) , Madrid, Spain.
authors.forename: Margarita
authors.initials: M
authors.lastname: Hierro-Oliva
authors.affiliation: Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Extremadura , Badajoz, Spain.|Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) , Madrid, Spain.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Pacha-Olivenza
authors.affiliation: Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Extremadura , Badajoz, Spain.|Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) , Madrid, Spain.
authors.forename: María Coronada
authors.initials: MC
authors.lastname: Fernández-Calderón
authors.affiliation: Laboratoris Sanifit , ParcBIT, Palma de Mallorca, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Perelló
authors.affiliation: Laboratoris Sanifit , ParcBIT, Palma de Mallorca, Spain.
authors.forename: Bernat
authors.initials: B
authors.lastname: Isern
authors.affiliation: Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Extremadura , Badajoz, Spain.|Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) , Madrid, Spain.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: González-Martín
authors.affiliation: Group of Cell Therapy and Tissue Engineering, Research Institute on Health Sciences (IUNICS), University of Balearic Islands , Ctra. Valldemossa km 7.5, 07122 Palma de Mallorca, Spain.|Instituto de Investigación Sanitaria de Palma , 07010 Palma, España.
authors.forename: Marta
authors.initials: M
authors.lastname: Monjo
authors.affiliation: Group of Cell Therapy and Tissue Engineering, Research Institute on Health Sciences (IUNICS), University of Balearic Islands , Ctra. Valldemossa km 7.5, 07122 Palma de Mallorca, Spain.|Instituto de Investigación Sanitaria de Palma , 07010 Palma, España.
authors.forename: Joana M
authors.initials: JM
authors.lastname: Ramis
mesh_terms: D001422:Bacterial Adhesion; D001842:Bone and Bones; D010833:Phytic Acid; D013499:Surface Properties; D014025:Titanium
chemical_list: D010833:Phytic Acid; D014025:Titanium
keywords: S. sanguinis; S.mutans; T-bag method; bioactive; coating; implant; phytic acid