3. Biomaterials for bone tissue-engineering - Essay Example

Running Head: BIOMATERIALS FOR BONE TISSUE ENGINEERING Biomaterials for Bone Tissue Engineering Submitted by Goes Here September, 2011Biomaterials for Bone Tissue EngineeringProperties of BiomaterialsIn the past scientists wanted the materials implanted to be ‘bio-inert’; however these day they want these materials to be bioactive. These bioactive materials should integrate with biological molecules or cells and regenerate tissues. When bones are concerned materials should be osteoinductive, osteoconductive and capable of osseointegration (Vandevord PJ, 2009).

Osteoinductive cells are capable of promoting the different ion of the progenitor cells down an osteoblastic lineage. Osteoconductive cells support the growth of bones and also encourage the growth of the surrounding bones. Osseointegration means the ability to integrate into surrounding bones. The ideal condition is that the tissue should be reabsorbed and may be even replaced by the body’s own regenerated biological tissues.Bioactive inorganic materials like tricalcium phosphate, HA, bioactive glasses have a large capacity to be re-absorbed.

This is definitely one of the positive points of inorganic materials. But the main problem is their brittle nature. This brittle nature means that the fracture toughness of the bones cannot b matched by these materials and thus is not ideal for picking heavy loads.Polymers such as collagen and hyaluronic acid are polymers which are interesting options for the use (Seeherman H, 2008).However they have weak mechanical properties and provide a possible risk of diseases if there is poor handling.

Hydrogels are the kind of polymers which are creating great buzz about their use. They have many advantages including the one that chemical biofunctionalisation and cell encapsulation and delivery are very straightforward.In order for the biomaterial to be like a real bone the toughness of a polymer needs to be combined with the compressive strength of an inorganic material (Hollinger, 2004). This improves their mechanical properties and degradation profiles.ProcessingOnce the adequate biodegradable polymer has been selected the next step is to find a suitable processing technique.

The processing methodology must not adversely affect the biocompatibility or the chemical properties of the chosen materials. Through the years a variety of processing techniques have been developed. Some of them will be discussed here by us.Solvent casting /Particulate Leaching – This method consists of dispersing calibrated materials such as sodium chloride or organic materials like saccharine particles in a polymer solution. The dispersion is processed after this either by casting or by using the method of freeze drying which results in the production of porous scaffolds.

Although the method is best known and widely used it has the disadvantage that some highly toxic solvents are used and membranes only 3 mm thick can be produced (Bikramjit Basu, 2009).Phase Inversion/Particulate Leaching – The main difference with the earlier technique is that the solvent is not allowed to evaporate but the solution film is placed in water which causes the PLGA to precipitate (Jabbari, 2007). This method prevents crystal deposition and also allows samples greater than 3 mm thickness to be produced.

Fiber bonding is a technique which consists of individual fibers woven into three dimensional patterns of variable sizes. The major advantage provided in this technique is the large surface area for cell attachment and the rapid diffusion of materials.Melt Molding/Particulate Leaching – This methodology consists of mixing the raw polymer with a porogen and loading in a mold. Heating of this mould above the glass transition temperature of the polymer is now done after which is immersed in a solvent for the dissolution of the porogen (Burdick, 2010).

ReferencesBikramjit Basu, D. S. (2009). Advanced Biomaterials: Fundamentals, Processing, and Applications. Amsterdam: John Wiley and Sons, 2009.Burdick, J. A. (2010). Biomaterials for Tissue Engineering Applications: A Review of the Past and Future Trends. Chicago: Springer.Hollinger, J. O. (2004). Bone Tissue Engineering. Los Angeles: CRC Press.Jabbari, E. (2007). Biologically-responsive hybrid biomaterials: a reference for material scientists and bioengineers. NewYork: World Scientific, 2010.

Seeherman H, L. R. (2008). A review of preclinical program development for evaluating injectable carriers for osteogenic factors. Journal of Bone and Joint Surgery , 96-108.Vandevord PJ, M. H. (2009). Characterisation of biomaterial blends for bone tissue engineering. Journal of Biomedical Materials Research , 585-590.