Biocompatibility material degradation

Another polysaccharide system that has received considerable interest is the chitosans which are water soluble derivatives of chitin. These materials appear to be very biocompatible and degradable and so are potentially excellent candidates as polymeric drug systems (27). 

Applications in medicine take advantage of the combination of such properties as biocompatibility and degradability. Neither the polymers themselves nor their degradation products can set free toxic materials or cause tissue-damaging processes. 

PU and silicone rubber are biocompatible materials which are commonly used in a variety of medical applications [53], e.g., as a raw material for central venous catheters and tracheotomy tubes. Although these materials are biocompatible, the side effects which occur during clinical use include inflammation, infection and biofilm formation and growth. This in turn initiates the degradation of the material, e.g., previous studies have proven that the degradation of PU catheters is caused by either oxidation or hydrolysis of the material [54]. The degradation of silicone rubber is a hydrolysis phenomenon [55], which could be catalysed by an acidic environment. 

Composite materials often show a good balance between toughness, strength and improved characteristics compared to individual components. PCL has been one of the most popular polymers used for bone TE scaffolds because of its biocompatibility, slow degradation and ease of electrospinning from a variety of solvents. MSC from rats cultured on electrospun PCL scaffolds, supplemented with osteogenic media... 

Biodegradable polyester-based composites have been extensively studied for use in medical applications owing to their biocompatible and degradable properties in the human body. The major reported examples in biomedical products are fracture-fixation devices, such as sutures, screws, micro titration plates, and delivery systems [77]. Cellulosic nanofiber reinforced PLA composite materials... 

The second component of biocompatibility is that of material degradation. It is emphasized here that degradation is a component of biocompatibility rather than a separate phenomena. There is still confusion over this since it is often perceived that degradation, which occurs on the material side of the interface, is the counterpart to biocompatibility which is equated with the other (tissue) side. This is not correct since degradation is the counterpart to the local host response, both being contributory to the biocompatibility of the system. 

The biocompatible material must be non-toxic and not produce cytotoxic degradation products. 

Bergsma, J.E., Rozema, F.R., Bos, R.R.M., Van Rozendaal, A.W.M., Dejong, W.H., Teppema, J.S.,Joziasse, C.A.P. (1995a) Biocompatibility and degradation mechanisms of predegraded and non-predegraded poly(lactide) implants an animal study. Journal of Materials Science Materials In Medicine, 6, 715-723. 

The biocompatibility of a biomaterial is primarily related to its interaction with the innate immune system, ie, ultimately the inflammatory response that is induced. Factors that influence such response include physicochemical and stmctural properties of the surface and the total surface area of the material. For a biodegradable material, these properties change over time and for most polymers, the pH also decreases in the tissue adjacent to the material during degradation. Consequently, the biocompatibility of a biomaterial needs to be reassessed at different steps, because a degrading material no longer possesses the properties of the original, biocompatible material. 

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