Characterization of Biphasic Calcium Phosphate Ceramics Synthesized

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A new breakthrough was envisioned in the review Materials Biphasic Calcium Phosphate Ceramics (CaPs) synthesized to make tricalcium phosphate (-TCP) and hydroxyapatite (HAp) from coral.

To study: Biomimetic ceramic composite: characterization, cellular response and in vivo biocompatibility. Image Credit: Sam0704 / Shutterstock.com

Using solid state synthesis followed by heat treatment at 1100 ° C for 1 hr to 7 days, SEM, X-ray diffractometry, Fourier transform infrared spectroscopy and Raman spectroscopy were used to assess prepared coral and biphasic derived from coral. samples of CaPs. In vitro cytotoxicity tests on mouse fibroblast cells were used to determine the cellular response of biphasic CaPs.

Coral exoskeletons as a source of calcium crystals

Coral exoskeletons feature a unique bonded porous design with tubular spaces comparable in size to normal teeth and bones, and thus have aroused the interest of orthodontic and maxillofacial surgeons. The existence of larger diameter macropores promotes nutrient transport, osteogenesis and tissue regeneration.

Coral exoskeletons are crystals of calcium carbonate such as aragonite or calcium. Their rate of decay as a rate of skeletal growth is too rapid to allow adequate bone growth, limiting clinical applications.

Method to create an HAp derived from coral

The recommended method of producing HAp derived from coral is hydrothermal conversion. However, this synthetic technique is not suitable for large-scale production because it is slow, requires complex pH changes, and has a small -TCP.

Using varying heats and periods at high temperature, a homogeneous combination of calcium and phosphate precursors can be combined in room temperature water to synthesize two-phase CP with a regulated ratio of HAp to -TCP via the pathway. solid state reaction. Extremely crystalline and two-phase CaPs have been produced with high repeatability and low operating cost.

XRD model of (a) the coral as prepared and (b) the commercial sample of coral calcium.

XRD model of (a) the coral as prepared and (b) the commercial sample of coral calcium. Image credit: Lin, H., et al., Materials

Based on research results from previous studies, HT-3 samples were selected for evaluation of heat treatment parameters indicated in in vitro cytotoxicity responses and in vivo bone defect testing. However, this method was time consuming and required complex pH changes.

Additionally, standard pore formation methods were difficult and rare to achieve the complex structures that were functionally relevant to the human skeleton and tooth enamel. The propagated scleractinous coral was used as a calcium precursor in this study, and the calcium carbonate microstructure had related microporosity.

Result of the research

After 8 hours of grinding, no apparent difference between the two previous powders, Ca2P2oh7 and CaCO3, were observed, although the area increased, leading to a guess. The current investigation has yielded similar results. Aragonite CaCO3 was a key component of the raw resources used, propagating the scleractinous coral.

After 1 hour of heat treatment, the starting components had completely decomposed into only two crystalline forms: HA and -TCP. After 1 h of heat treatment, the relative proportion of -TCP was greater than that of HAp and decreased with prolonged heat treatment, indicating that -TCP was readily produced.

The significant influence of the initial materials and -TCP aided in the translation of CaCO3 at -TCP. In addition, the Ca / P ratio of the starting materials created ideal conditions for the synthesis of -TCP.

Due to their comparable chemical components, the diffraction patterns of the CaP-based combinations overlapped. As a result, vibratory spectroscopies have helped characterize the vibrations for amorphous or crystalline forms of these substances. The results of FTIR and Raman spectra in the current investigation were in excellent agreement with the results of DRX.

The appearance of Raman OH peaks may be related to precipitated moisture due to the extremely hygroscopic characteristics of the phosphates and the development of the air temperature environment after the heat treatment. The OH peak decreased as the heat treatment time increased, indicating that the transition from -TCP to HA was caused by the presence of water and the availability of additional hydroxyl groups.

XRD models of samples prepared by heat treatment of coral as prepared and DCPA at various times, including reference spectra for JCPDS 01-084-1988 and 00-009-0169.

XRD models of samples prepared by heat treatment of coral as prepared and DCPA at various times, including reference spectra for JCPDS 01-084-1988 and 00-009-0169. Image credit: Lin, H., et al., Materials

The advantage of ceramic composites

As ceramic composite coatings, the hard particles are usually placed in the top layers near the metal matrices. They have advantages in terms of excellent wear resistance, corrosion resistance and the ability to operate at high temperatures. Ceramic matrix composites (CMC) are also often used in the aeronautical and energy industries (turbojets, thermal insulation by mechanical reentry) (heat exchangers, walls of nuclear fusion reactors).

In many applications, a permanent or temporary seal between CMC parts and surrounding materials is required.

Biomimetic ceramic composites using coral skeletons are a good breakthrough that can be used in healthcare sectors. Biphasic CaPs produced from corals, which comprised 61 percent HAp and 39 percent -TCP (termed HT-3) were not cytotoxic.

In addition, there were no substantial differences in local tissue reactivity between the HT-3 sample and autogenous bone. Due to its superior biocompatibility, the synthesized biphasic coral-derived CaPs are a possibility for bone grafting.

The references

Lin, H., et al. (2021). Biomimetic ceramic composite: characterization, cellular response and in vivo biocompatibility. Publication: December 1, 2021. Documents 2021, 14 (23), 7374; https://www.mdpi.com/1996-1944/14/23/7374

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