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Additive Manufacturing of Biomaterials
Published in Atul Babbar, Ankit Sharma, Vivek Jain, Dheeraj Gupta, Additive Manufacturing Processes in Biomedical Engineering, 2023
Hydroxyapatite (HA) is a derivative of tricalcium phosphate with the same Ca:P ratio of 1.67 as bone structure, so it has better biocompatibility compared with other CaPs compounds. Seitz et al., in 2005, produced binder-jetted HA scaffolds and showed that the 3D-printed parts sintered at 1250 °C could have various levels of porosity based on the designed microchannels where the comprehensive strength of approximately 22 MPa was reported for the dense structure. Another derivative of calcium phosphate is tetracalcium phosphate (TTCP), with a Ca:P ratio of 2. As stated earlier, the higher the Ca:P ratio, the lower degradation can be expected for the CaPs compounds; therefore, TTCP has the highest biocompatibility among the CaPs widely used for bone matrix. Also, dicalcium phosphate (DCP) is another common calcium phosphate bioceramic with a Ca:P ratio of 1. Vorndran et al., in 2008, proposed binder jetting from two different mixtures made of powders with a Ca:P ratio of 1.7 (method A) and TTCP/DCP composite (method B) to study the printability, densification, and mechanical behavior of the 3D-printed scaffolds. Porous scaffolds produced by method A showed a higher print resolution with a porosity of 56% and compressive strength of 7.4 ± 0.7 MPa while method B showed a porosity of 60% with compressive strength of 1.2 ± 0.2 MPa. Klammert et al., in 2010, reported applying an acid solution as a binder on calcium phosphate to print TTCP or DCP powders using binder jet 3D printing (BJ3DP) for cranial and maxillofacial defect fixations. Afterward, hydrothermal treatment of the implants (refers to Figure 9.5) caused the brushite compound to convert to monetite with a high print resolution and part accuracy. In another study, Habibovic et al., in 2008, a low-temperature direct 3D printing was employed to fabricate brushite and monetite implants with various shapes.
Wound closure, angiogenesis and antibacterial behaviors of tetracalcium phosphate/hydroxyethyl cellulose/hyaluronic acid/gelatin composite dermal scaffolds
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Atefeh Derakhshani, Saeed Hesaraki, Nader Nezafati, Mahmoud Azami
Tetracalcium phosphate (TTCP) is a type of calcium phosphate used as starting materials in calcium phosphate cement, applied in bone defects [32]. TTCP has a Ca/P ratio of 2.0 and is the most basic calcium phosphate compound. The water solubility of TTCP is higher than that of hydroxyapatite (HAp), and when subjects to water or humidity, it begins to hydrolyze to HAp and calcium hydroxide, Ca(OH)2, from its surfaces, according to the following reaction [33]: