Biocompatibility of dense hydroxyapatite prepared using an SPS process.

Area of Science:

• Biomaterials Science
• Materials Engineering
• Bioceramics

Background:

• Hydroxyapatite (HAp) is a key biomaterial for bone regeneration.
• Conventional methods for HAp sintering often require high temperatures.
• Investigating novel sintering techniques to improve HAp bioactivity is crucial.

Purpose of the Study:

• To prepare dense hydroxyapatite (HAp) materials at lower temperatures using spark plasma sintering (SPS).
• To evaluate and compare the in vitro bioactivity of HAp sintered by SPS versus conventional hot-pressing (HP).
• To explore the relationship between surface charge, electric poling, and bioactivity in HAp.

Main Methods:

• Spark plasma sintering (SPS) was used to prepare dense HAp samples at relatively low temperatures.
• In vitro bioactivity was assessed by immersing HAp samples in simulated body fluid (SBF) for 2 days.
• Surface charge analysis and electric poling measurements using thermally stimulated current (TSC) technique were performed.

Main Results:

• HAp samples sintered by SPS exhibited significant growth of bone-like HAp crystals after 2 days in SBF.
• HAp samples sintered by conventional HP showed no bone-like crystal growth under the same conditions.
• Negatively charged HAp surfaces produced via SPS supported larger bone-like HAp crystal growth compared to positively charged surfaces.

Conclusions:

• Spark plasma sintering is an effective method for producing bioactive HAp at lower temperatures.
• The enhanced bioactivity of SPS-processed HAp is attributed to potential ion deficiencies and electric poling effects.
• Surface charge plays a role in the in vitro bioactivity of hydroxyapatite.