Cross-linked chitosan improves the mechanical properties of calcium phosphate–chitosan cement

Abstract

Calcium phosphate (CaP) cements are highly applicable and valuable materials for filling bone defects by minimally invasive procedures. Chitosan (CS) biopolymer is also considered as one of the promising biomaterial candidates in bone tissue engineering. In the present study, some key features of CaP-CS were significantly improved by developing a novel CaP-CS composite. For this purpose, CS was the first cross-linked with tripolyphosphate (TPP) and then mixed with CaP matrix. A group of CaP-CS samples without cross-linking was also prepared. Samples were fabricated and tested based on the known standards. Additionally, the effect of different powder (P) to liquid (L) ratios was also investigated. Both cross-linked and uncross-linked CaP-CS samples showed excellent washout resistance. The most significant effects were observed on Young's modulus and compressive strength in wet condition as well as surface hardness. In dry conditions, the Young's modulus of cross-linked samples were slightly improved. Based on the presented results, cross-linking does not have significant effect on porosity. As expected, by increasing the P/L ratio of sample, ductility and injectabilty were decreased. However, in the most cases, mechanical properties were enhanced. The results have shown that cross-linking can be improved the mechanical properties of CaP-CS and hence it can be used for bone tissue engineering applications.

Injectable porous nano-hydroxyapatite/chitosan/tripolyphosphate scaffolds with improved compressive strength for bone regeneration

“…We have adopted the fabrication procedure used by our group in previous studies [6, 10, 37, 40, 41]. The objective of this study was to obtain porous spherical scaffolds using chitosan, increase the mechanical strength of the scaffolds using nHA and characterized the scaffolds for its morphological, mechanical, physiochemical, cell attachment and cell cytotoxicity properties.…”

“…It has been a problem to test mechanical properties of non-cylindrical scaffolds due to the absence of standard procedure. As a solution, researchers have prepared cylindrical scaffolds or films by aggregating primary scaffold materials or using the same compositions of the scaffolds [35, 37, 38]. However, these methods do not present the exact mechanical properties of original scaffold because of the binding methods of scaffolds and the area exposed to the force on scaffolds.…”

Blooming gelatin: an individual additive for enhancing nanoapatite precipitation, physical properties, and osteoblastic responses of nanostructured macroporous calcium phosphate bone cements

“…The powder phase of the CPC was prepared by mixing the synthesized TTCP, Ca 4 (PO 4 ) 2 O (with mean particle size of 12.1±2.3 µm), and commercially available DCPA, CaHPO 4 (with mean particle size of 6.5±1.2 µm) at a molecular ratio of 1:1. A 6 wt.% solution of Na 2 HPO 4 with various concentrations of gelatin type B (225 bloom; Sigma-Aldrich) were prepared as liquid phase.…”

“…Moreover, the bands at 1,415 and 1,450 cm −1 are attributed to carbonate group in apatite lattice, which reflect the formation of carbonated apatite. The band at 950 cm is also related to the HPO 4 2− group. It confirms that the formed apatite is a calcium-deficient phase.…”

“…2,3 Several additives, especially in the form of natural polymers, have been used to correct the physical and biological properties of CPCs. [4][5][6][7] Gelatin is a partially hydrolyzed form of collagen, which is a natural component of bone matrix. Gelatin, in its various physical forms, has been widely used in bone-related composites to enhance the physical and biological properties.…”