Calcium phosphates-based (CaPs) nanocoatings on metallic prosthesis are widely studied in orthopedics and dentistry because they mimic the mineral component of native human bone and favor the osseointegration process. Despite the fact that different calcium phosphates have different properties (composition, crystallinity, and ion release), only stoichiometric hydroxyapatite (HA) films have been analyzed in deep. Here, we have realized films of different CaPs (HA, beta-tricalcium phosphate (β-TCP) and brushite (DCPD)) onto Ti6Al4V microrough substrates by Ionized Jet Deposition (IJD). We have implemented the heating of substrates at 400°C during deposition to see the effect on coating properties.

Different film features are evaluated: morphology and topography (FEG-SEM, AFM), physical-chemical composition (FT-IR and EDS), dissolution profile and adhesion to substrate (scratch test), with a focus on how the different CaPs and temperature changed the coating features. After coating optimization, we have studied the in vitro BM-MSC behavior, in term of viability and early adhesion.

We have obtained good transfer of fidelity in composition from target to coating for all CaPs, with nanostructured films formed by globular aggregates (~300 nm diameter), with homogeneous and uniform coverage of the substrate surface, without cracks. The heating during deposition has increased the adhesion of the films to the substrate, with higher stability in medium immersion and wettability, features that can improve the biological behavior of cells. All CaP coatings have showed excellent biocompatibility, with DCPD coating that promote higher cells viability at 14 days respect to HA and β- TCP films. About the early cell adhesion, the BM-MSC have showed switch from a globular to an elongated morphology at 6 hours in all coatings respect to the uncoated titanium, sign of better adhesion.

From these results, the fabrication of different CaP nanocoatings with IJD can be a promising for applications in orthopedics and dentistry.

Aims: to investigate the role of gelatin on the setting properties of α-tricalcium phosphate based cement.

Methods: gelatin α-TCP powders were prepared by grinding and sieving the solid compounds obtained by casting gelatin aqueous solutions containing a-TCP. 5% wt of CaHPO42H2O were added to the cement powders before mixing with the liquid phase, with a L/P ratio of 0.3 mL/g. Teflon moulds were used to prepare cement cylinders 6 mm in diameter and 12 mm high. X-ray diffraction analysis, mechanical tests, SEM, dsc and TG investigations were carried out on the cements after different times of soaking in SBF.

Results: The setting reaction of the control cement is completed in 7 days, whereas the transformation into apatite of the cements at high gelatin content occurs in just 2 days of aging in SBF. The fractured surface of the aged control cement is covered with entangled plate like apatite crystals, whereas gelatin cements display much more compact surfaces, most likely because of the inhibiting effect of gelatin on apatite crystal growth. The microstructural modifications are in agreement with the reduction of the total porosity, and with the improvement of the mechanical properties of the aged cements, on increasing gelatin content. The compressive strength of the cements increases linearly with the increase of gelatin. The results of the thermogravimetric analysis indicate a strong interaction between gelatin and hydroxyapatite crystals.

Conclusions: the results of this paper indicate that gelatin can be successfully used to improve and modulate the mechanical properties of α-TCP-based cements.