Collective substitutions of selective rare earths (Yb3+, Dy3+, Tb3+, Gd3+, Eu3+, Nd3+) in ZrO2: an exciting prospect for biomedical applications

Enhancing the zircon yield through the addition of calcium phosphates into ZrO2-SiO2 binary systems: synthesis and structural, morphological, mechanical and in vitro analysis

The crystallization of ZrSiO4 is generally accomplished by the addition of mineralizers into ZrO2-SiO2 binary oxides. The current investigation aimed to investigate the effect of adding calcium phosphates into ZrO2-SiO2 binary oxides on the yield of ZrSiO4. The concentration of calcium phosphate additions were varied to obtain ZrSiO4 that fetches improved mechanical and biological properties for application in hard tissue replacements. The findings highlight the significant role of Ca2+ and P5+ in triggering the ZrSiO4 formation via their accommodation at the Zr4+ and Si4+ sites. Especially, calcium phosphate additions trigger the t- → m-ZrO2 transition beyond 1000 °C, which consequently reacts with SiO2 to promote ZrSiO4 formation. Calcium phosphates are accommodated at the lattice sites of ZrSiO4 with a maximum limit of 20 mol%, beyond which the crystallization of β-Ca3(PO4)2 is noticed. The optimum amount of 20 mol% of calcium phosphates displayed a better strength than that of all the investigated specimens. More than 80% of cell viability in MG-63 cells was invariably determined in all the calcium phosphate-added ZrSiO4 systems.

Structural and electrochemical corrosion studies of spin coated ZrO2 thin films over stainless steel alloy for bone defect applications

Sol-Gel-based reaction mixture sols have been long used to fabricate dense and uniform bioactive coatings with superior mechanical stability over metallic implants. On account of precise control over synthesis, fabrication, formed and low temperature of processing, this technology is one of the most feasible routes to produce bio-ceramic coatings. The study aims to develop a physical barrier over metal implants in form of bioinert Zirconia coatings, phase-stabilized using Dysprosium. The metallic substrates were cut into 10 mm × 10 mm samples and diamond polished after being polished with a 1000 grade emery sheet. Novel spin-coated zirconia films were fabricated over 316L Stainless steel substrates and were sintered at 600°C to obtain firm and uniform crack-free coatings. The thickness of the coatings was determined by ELCA-D meter thermal analysis was performed using TGA-DTA. Phase determination was performed using X-Ray diffraction followed by morphological investigations using Scanning electron microscopy. The corrosion resistance was evaluated with Polarization studies and electrokinetic data was derived using Tafel extrapolation. Biocompatibility evaluation was performed against MG-63 cell lines and RBCs along with bone-forming ability in vitro in SBF. Stable crack-free 3 Layer coatings fabricated at 2000 rpm for 3 s with a thickness of around 1 μm were found to be optimal for corrosion resistance behavior of steel implants at a low I_Corr value of 0.501 µA/cm² and adhesion strength of 40.93 MPa when untreated falling down to 39.92 MPa when immersed in SBF. The study concludes that medium rpm coatings sustain enough sol to produce crack-free coatings that form a strong physical barrier between body fluid and implant surface thereby reducing the attack of corrosive ions and protecting the implant surface without participating in any form of bioactivity but supporting native bone regeneration capabilities.

Structure, mechanical, optical, and imaging contrast features of Yb3+ , Dy3+ , Tb3+ , Gd3+ , Eu3+ , and Nd3+ substituted Y2 O3 -Ln2 O3 solid solution

Bulk ceramic that possess the combined features of structural stability at elevated temperatures, appropriate mechanical stability, luminescence features, magnetic resonance (MR) and computed tomography (CT) imaging capacity in a single platform is considered an exciting prospect in biomedical applications. In this study, six different lanthanides (Ln³⁺ :Yb³⁺ , Dy³⁺ , Tb³⁺ , Gd³⁺ , Eu³⁺ , and Nd³⁺ ) were combined together to yield a Y₂ O₃ :Ln₂ O₃ solid solution and subsequently tested for the proposed application. Three different Y₂ O₃ :Ln₂ O₃ solid solutions were formed by varying the concentrations of Ln³⁺ precursors. A unique cubic crystal structure with Ia-3 (206) space setting is retained until 1500 °C and moreover an expanded lattice is accomplished with the gradual inclusion of six different Ln³⁺ . Optical analysis inferred the characteristic electronic transitions of all the Ln³⁺ and moreover up-conversion and down-conversion emission behavior were also attributed by the material during excitation at 795 and 350 nm. Nanoindentation studies exercised on the material envisaged reasonably enhanced hardness and Young's modulus values. Further, the enhanced CT imaging potential alongside in vitro MRI study deliberating the longitudinal (T₁ ) and transverse (T₂ ) relaxivity ability of the material is also established.