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Poster De Conférence Année : 2021

Development of advanced bioactive glass-based coatings by electrostatic spray deposition


Introduction Bioactive glasses (BG) are the subject of intensive investigation as a bone replacement material since the discovery of a 4-component glass in 1969 by Hench, nowadays known as 45S5 (46.1 SiO2 ̶ 24.4 Na2O ̶ 26.9 CaO ̶ 2.6 P2O5 % mol) [1]. However, due to brittleness and poor mechanical properties, direct BG clinical applications are limited to non-load-bearing implants. Nevertheless, BG can be employed as coatings on a metallic substrate to combine their biological performance with mechanical strength. Many deposition processes are currently investigated to produce BG coatings [2]. However, the fabrication of BG coatings by sol-gel method coupled with the electrostatic spray deposition (ESD) has never been attempted to the far of our knowledge. Based on electrohydrodynamics laws, ESD is a simple and low-cost technique that allows the deposition of films with precise control of thickness, microstructure, and chemical composition. In our previous work, by coupling the sol-gel method with the ESD technique, we have obtained a robust, one-step method for the fabrication of single-phase nanocrystalline hydroxyapatite coatings [3]. This study focuses on manufacturing BG coatings belonging to the SiO2-CaO-P2O5 system, starting from homogeneous liquid precursor solutions deposited on Ti6Al4V substrates. Here, through this technique, we have successfully obtained in one-step coatings with optimized S85 (85 SiO2 ̶ 10 CaO ̶ 5 P2O5 mol. %), S75 (75 SiO2 ̶ 20 CaO ̶ 5 P2O5 mol. %) and S58 (58 SiO2 ̶ 37 CaO ̶ 5 P2O5 mol. %) compositions [4]. Experimental methods Bioactive glasses (BG) coatings were prepared using a vertical ESD set-up on polished commercial Ti6Al4V ELI plates. Precursor solutions were prepared by using either triethyl phosphate, referred to as TEP (Aldrich, 99.8%) or H3PO4 (Aldrich, 85 %) as P(V) source, tetraethyl orthosilicate, TEOS (Aldrich, 99,999%) as Si(IV) source and Ca(NO3)2.4H2O (Merck, 99.95%) as Ca(II) source. Methanol (CH3-OH, MetOH), Ethanol (CH3-CH2OH, EtOH), and diethylene glycol monobutyl ether, referred to as butyl carbitol (C4H9(OCH2CH2)2OH, BC), were chosen as solvents for the preparation of the precursor solution. To investigate the influence of processing conditions on the characteristics of the coatings, such as composition, structural and microstructural properties, several ESD parameters were considered -i.e. nature of P(V) precursor, absolute precursor solution concentrations, solvent composition, substrate temperature, and deposition time. The microstructure and composition of the obtained coatings were characterized by scanning electron microscopy (SEM) coupled with an EDS probe. Their structural properties were determined using X-ray diffraction (XRD) and Raman spectroscopy. Assessment of in vitro bioactivity was carried out in simulated body fluid solution (SBF) according to the ISO standard norm (22317: 2014) on optimized S85, S75, and S58 coatings. Results and discussion All BG-coatings deposited by ESD displayed an amorphous character as detected by XRD. Microstructures from denser to coral-like and highly porous morphologies were successfully obtained regardless of the coating composition (Fig 1). EDX analyses show the presence of silicon, calcium, and phosphorus homogeneously distributed in the volume of films, according to the above formulations. Besides, their bioactivity behavior has been studied by immersion in SBF solution for 24 h. The biological performance of BG was found to be strongly dependent on their texture. Highly porous coatings led to remarkable bioactivity of the films with S75 and S58 compositions, compared with more compacted ones. The films with S85 compositions, whatever is the morphology, were found highly reactive. Indeed, almost complete dissolution was carried out within 24 h of immersion. Conclusion The present work introduces an innovative preparation of glass-based coatings, prepared for the first time by coupling the sol-gel method with ESD. Coatings with S85, S75, S58 compositions were successfully obtained after optimization of i) the precursor solution, and ii) the substrate temperature. All the obtained deposited coatings were crack-free and presented an amorphous environment with original coating microstructures. Morphologies ranging from highly porous coral-like toward more compact cauliflower-type were obtained showing the potential of ESD for easily tune the coating texture. Furthermore, the ESD method has proven to be very successful for developing highly reactive bioactive glass coatings that offer complete transformation into an apatite layer after 24 h of soaking in SBF for S75 and S58 BG coatings. Mechanical and further biological characterizations of the coatings are in progress. References [1] Hulbert, S. F., Hench, L. L., Forbers, D., Bowman, L. S. (1982). History of bioceramics. Ceramics International, 8 (4), 131. [2] Sergi, R., Bellucci, D., Cannillo, V. (2020). A comprehensive review of bioactive glass coatings: State of the art, challenges and future perspectives. Coatings, 10 (8), 757. [3] Müller, V., Pagnier, T., Tadier, S., Gremillard, L., Jobbagy, M., Djurado, E. (2021). Design of advanced one-step hydroxyapatite coatings for biomedical applications using the electrostatic spray deposition. Applied Surface Science, 541, 148462. [4] Müller, V., Jobbagy, M., Djurado, E., Materials Science and Engineering: C, to be submitted.


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Dates et versions

hal-03246151 , version 1 (02-06-2021)


  • HAL Id : hal-03246151 , version 1


Verónica Müller, Matias Jobbagy, Elisabeth Djurado. Development of advanced bioactive glass-based coatings by electrostatic spray deposition. 31st Conference of the European Society for Biomaterials, Sep 2021, Porto, Portugal. ⟨hal-03246151⟩
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