Role of Ti3AlC2 MAX phase in regulating biodegradation and improving electrical properties of calcium silicate ceramic for bone repair applications

Abstract

Calcium silicate ceramic is a promising bioceramic for various biomedical applications, but its high biodegradation rate and low strength restrict its clinical utility. As a result, the study devised an innovative solution to address these issues by utilizing the titanium aluminum carbide phase, potentially for the first time in biological applications, in conjugation with hydroxyapatite. Then, using powder metallurgy technology, they added these phases to calcium silicate to create nanocomposites. After soaking in simulated body fluid for ten days, the produced nanocomposites were assessed for bioactivity and biodegradability using scanning electron microscopy, inductively coupled plasma-atomic emission spectroscopy, and weight loss assays. Their electrical and dielectric properties were also measured before and after soaking in the simulated body fluid solution. Furthermore, the tribo-mechanical properties of all sintered samples were measured. Interestingly, adding 40% hydroxyapatite nanoparticles to calcium silicate reduced the porosity from 12 to 6%. However, adding five vol% of the titanium aluminum carbide phase to the same sample increased the porosity to 8%. Importantly, these recorded percentages of porosity were comparable to those of compact bone porosity, which range from 5 to 13%. The addition of hydroxyapatite and titanium aluminum carbide phase significantly improved the rapid biodegradation of calcium silicate, albeit with a slight decrease in its bioactive properties, as evidenced by the incomplete surface coverage of the samples with the hydroxyapatite layer in the scanning electron microscopy images. The electrical properties of the nanocomposites were better with the addition of hydroxyapatite and titanium aluminum carbide phase, which helped the bone heal faster. The addition of a titanium aluminum carbide phase significantly improved the mechanical properties of the resulting nanocomposites. For example, the calculated values for compressive strength of all examined samples were 131, 115, 105, 147, and 135 MPa. Based on the results, the prepared samples can be used in orthopaedic and dental applications.

Keywords: Bioactivity; Biodegradation; Bone fracture healing applications; Calcium silicate; Electrical conductivity.

Figure 1

Particle size distribution of as-received (a) CaCO₃ and (b) CaHPO₄.2H₂O powders.

Figure 2

The average particle sizes of the raw materials used, i.e., a) CaCO₃ and b) CaHPO₄.2H₂O,c) CaSiO₃, d) HA, and e) Ti₃AlC₂ powders.

Figure 3

XRD patterns of as-prepared raw materials, i.e.,a) CaSiO₃, b) HA, and c) Ti₃AlC₂ powders.

Figure 4

HRTEM images and the corresponding SEAD patterns of a) CaSiO₃, b) HA, and c) Ti₃AlC₂ nanopowders.

Figure 5

The XRD patterns of all samples after sintering at 1050 °C for one hour.

Figure 6

FESEM images, at two different magnifications, of CHM1 (a, b), CHM2 (c, d), CHM3 (e, f), CHM4 (g, h), and CHM5 (i, j) samples before soaking in SBF solution.

Figure 7

FESEM micrographs of (a) CHM1, (b) CHM2, (c) CHM3, (d) CHM4, and (e) CHM5 samples coupled with the EDX spectra of the formed HA layer on the surfaces of the CHM1, CHM2, and CHM3 samples after soaking in the SBF solution for ten days.

Figure 8

Percentage weight loss of all prepared samples after treatment with SBF solution for ten days.

Figure 9

(a) Bulk density, (b) relative density, and (c) total porosity of all samples sintered at 1050 ℃ for one hour.

Figure 10

(a) Microhardness and (b) compressive strength of all samples sintered at 1050 °C for one hour.

Figure 11

(a) Wear rate, (b) coefficient of friction, and (c) wear rate versus microhardness of all sintered samples at different applied loads, i.e., 20 and 40 N.

Figure 12

The AC electrical conductivity at a) lower frequency, i.e., 1 MHz, and b) higher frequency, i.e., 20 MHz, of all sintered samples measured before and after immersion in the SBF solution for ten days.

Figure 13

The dielectric constant at a) 1 MHz and b) 20 MHz of all sintered samples before and after soaking in the SBF solution for ten days.

Figure 14

The dielectric loss at a) 1 MHz and b) 20 MHz of all sintered samples before and after soaking in the SBF solution for ten days.