Highlights The interaction between the AMP nucleotide and a biomimetic apatite was investigated  Data fitted to a Sips isotherm with parameters suggesting adsorptive cooperativity  Enhanced adsorption was pointed out in acidic conditions  AMP Raman band shifts/enhancements were noticed, indicative of chemical interaction ABSTRACTThis work investigates the interaction between the nucleotide adenosine 5' monophosphate molecule (AMP) and a biomimetic nanocrystalline carbonated apatite as a model for bone mineral. The analogy of the apatite phase used in this work with biological apatite was first pointed out by complementary techniques. AMP adsorption isotherms were then investigated. Obtained data were fitted to a Sips isotherm with an exponent greater than one suggesting positive cooperativity among adsorbed molecules. The data were compared to a previous study relative to the adsorption of another nucleotide, cytidine monophosphate (CMP) onto a similar substrate, evidencing some effect of the chemical nature of the nucleic base. An enhanced adsorption was observed under acidic (pH 6) conditions as opposed to pH 7.4, which parallels the case of DNA adsorption on biomimetic apatite. An estimated standard Gibbs free energy associated to the adsorption process (G°a ds  -22 kJ/mol) intermediate between "physisorption" and "chemisorption" was found. The analysis of the solids after adsorption pointed to the preservation of the main characteristics of the apatite substrate but shifts or enhancements of Raman bands attributed to AMP showed the existence of chemical interactions involving both the phosphate and adenine parts of AMP. This contribution adds to the works conducted in view of better understanding the interaction of DNA/RNA and their constitutive nucleotides and the surface of biomimetic apatites. It could prove helpful in disciplines such as bone diagenesis (DNA/apatite interface in aged bones) or nanomedicine (setup of DNA-or RNA-loaded apatite systems). Also, the adsorption of nucleic acids on minerals like apatites could have played a role in the preservation of such biomolecules in the varying conditions known to exist at the origin of life on Earth, underlining the importance of dedicated adsorption studies.

Ion substitution Human stem cells Bone biomaterial Calcium phosphate Dicalcium phosphate dihydrate, DCPD (CaHP0 4 •2H 2 O), brushite, is an important calcium phosphate compound encountered in mineralized tissues and used in medicine, especially in bone cernent for mulations. However, the use of DCPD as direct implantable biomaterial has not received dedicated attention. In addition, the possibility to dope DCPD with biologically active ions to modulate its per formances was not systematically explored. We have investigated in depth the doping of DCPD with Mg 2+ , sr2 + , Zn 2+ , Cu 2+ , and Ag + ions. Clear modifications in terms of chemical composition, particl e size, pore distribution, crystal morphology, and affinity for water were pointed out. Then, the samples were cultured with human adipose derived stem cells to explore cytotoxicity and proliferation. Various be haviors were noticed dependent on the incorporated metal ions. Such DCPD compounds associated with bioactive metal ions, and particularly Ag + and Zn 2+ , appear promising as a new family of reactive ma terials for use, as such or in combination, in bone related applications.

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This is an author's version published in: http://oatao.univ-toulouse.fr/24455

This study investigated the effect of bioglass (melting)-polyvinyl alcohol (BG (M)-PVA) and bioglass (melting)-polyvinyl alcohol-20 %ciprofloxacin (BG(M)-PVA-20Cip) in improving antioxidant activity and regenerating bone capacity. These composites were implanted in femoral condyles of ovariectomized Wistar rats and compared to that of controls groups. After the different period of implantation (15, 30, 60 and 90 days), the treatment of ovariectomized rats with BG(M)-PVA-20Cip showed a significantly higher malondialdehyde concentration when compared to that of BG(M)-PVA group. The superoxide dismutase, glutathione peroxidase and catalase in BG(M)-PVA-20Cip group showed significantly lower activities when compared to those in BG(M)-PVA group. So, BG(M)-PVA is more tolerated by organism than BG(M)-PVA-20Cip. Moreover, the alkaline phosphatase and acid phosphatase activities showed an excellent osteoinductive property of BG (M)-PVA. This property decreased with the presence of ciprofloxacin which is confirmed by histopathological analysis. Several physicochemical techniques showed a rapid reduction in Si and Na in one hand and an accelerator rise in Ca and P ions concentrations in other hand in BG(M)-PVA than in the BG(M)-PVA-20Cip. Therefore, the incorporation of ciprofloxacin in BG(M)-PVA is characterized by a prooxidant effect in oxidant-antioxidant balance at the beginning of treatment and a retard effect of formation of apatitic phase.