“…Many other techniques, such as replication of polymer foams by impregnation [230,231,232,235,492,493,494,495] (Figure 7), various types of casting [217,219,223,225,496,497,498,499,500,501,502,503,504,505], suspension foaming [120], surfactant washing [506], as well as several other approaches [86,89,92,161,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541...…”
Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.
“…Many other techniques, such as replication of polymer foams by impregnation [230,231,232,235,492,493,494,495] (Figure 7), various types of casting [217,219,223,225,496,497,498,499,500,501,502,503,504,505], suspension foaming [120], surfactant washing [506], as well as several other approaches [86,89,92,161,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541...…”
Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.
“…Among the various phases of calcium phosphate, the usage of hydroxyapatite [Ca10(PO4)6(OH)2, HA] and bheta-tricalcium phosphate [Ca3(PO4)2, β-TCP] have increased in clinical field due to their similar chemical composition and crystallographic structure to natural bone. These materials may be employed in various forms such as porous blocks, dense body, granular forms and hybrid composites to fill bone defects or voids [3][4][5][6][7][8].…”
Hydroxyapatite (HA) powders were synthesized using eggshell waste through hydrothermal method to develop bioceramics materials for medical applications. The effects of the pH conditions during the synthesis on the phase behaviour, crystallite size, crystallinity and morphology of as-synthesized ceramic powders were evaluated. The XRD patterns showed that HA was only the main phase present in the as-synthesized powder after being calcined at 400°C. However, EDX measurement detected the presence of Mg as trace elements which originated from the eggshell as starting materials. The crystallite size and crystallinity of the HA powders were increased when the powders were synthesized in acidic condition as compared to basic condition. FESEM images showed that HA powder with nano-sized rods and spherical morphologies were obtained from the powders that were synthesized at pH 5, while the powder particles synthesized at basic condition at pH 9 produced elongated rod-shape particles. The PSD results showed that the synthesized HA were in agglomerated form which were also confirmed by FESEM images.
“…However, an increased porosity can compromise the structural stability of the biomaterial, and therefore a balance is needed between the mechanical and mass transport function of the construct to create an optimal scaffold system (Loh and Choong 2013 ). A drawback of this method is that new tissue formation of often limited to the surface of the construct with minimum cell growth near the centre of necrotic zones in the centre of the construct (Sopyan et al 2008 ). Furthermore solvent residues from the porogen or solvent could be harmful/toxic to cells (Sopyan et al 2008 ).…”
“…A drawback of this method is that new tissue formation of often limited to the surface of the construct with minimum cell growth near the centre of necrotic zones in the centre of the construct (Sopyan et al 2008 ). Furthermore solvent residues from the porogen or solvent could be harmful/toxic to cells (Sopyan et al 2008 ). Fig.…”
Bioreactors hold a lot of promise for tissue engineering and regenerative medicine applications. They have multiple uses including cell cultivation for therapeutic production and for in vitro organ modelling to provide a more physiologically relevant environment for cultures compared to conventional static conditions. Bioreactors are often used in combination with scaffolds as the nutrient flow can enhance oxygen and diffusion throughout the 3D constructs to prevent the formation of necrotic cores. A variety of scaffolds have been fabricated to achieve a structural architecture that mimic native extracellular matrix. Future developments of in vitro models will incorporate the ability to non-invasively monitor the cellular microenvironment to enhance the understanding of in vitro conditions. This review details current advancements in bioreactor and scaffold systems and provides insight on how in vitro models can be augmented for future biomedical applications.
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