Novel interconnected nanochannel hydroxyapatite ceramics: synthesis, microstructure, and permeability

Uniform interconnected micro/nanoporous ceramics with good mechanical properties hold universal applications in biomedical and engineering fields. Herein, using hydroxyapatite (HAP) microtubes as the raw material instead of traditional particles, a novel interconnected nanochannel hydroxyapatite ceramic was fabricated successfully through one-step microwave sintering method without the addition of pore generators. The tubular structure of the HAP microtubes remains even after microwave sintering, which endows the ceramic with uniform interconnected nanochannels and 3-D porous structure. The HAP microtube nanochannel ceramic has a narrow pore size distribution from 400 nm to 600 nm, and exhibits well permeability, high adsorption/desorption ability. The porosity is about 30%, the HAP microtube nanochannel ceramic can be totally dyed by methylene blue within several minutes, and the blue dye can be desorbed completely in 45 min by ultrasonic vibration. In addition, due to the one-dimensional structure of the HAP microtubes, the HAP microtube nanochannel ceramic has smaller shrinkage, bigger porosity, and better toughness than the control sample fabricated by nanoparticles. Base on the uniform interconnected nanochannel structure, well permeability, high adsorption/desorption ability, the HAP microtube nanochannel ceramic fabricated here may be a promising candidate for many applications in biomedical engineering, environmental engineering, and energy engineering.