Bioadhesion artificial

This artificial bioadhesion does not characterize the natural situation, where spontaneous protein adsorption precedes cell-surface contact. Mohandas and co-workers (18) recognized this problem and have extended their studies to protein-coated surfaces as well. 

Artificial membranes soaked in animal mucin dispersions or animal model mucosae are used as biological substrates. Another apparatus proposed for in vitro measurements of bioadhesive properties of liquid formulations (polymer solutions or pessaries upon melting) consists of a thermostated inclined plane over which a mucosal membrane or a mucin film is layered. This test measures, as a function of time, the amount of formulation that after contact with the biological substrate, drops on a microbalance placed under the inclined plane [86] (Figure 22.3). 

The bioadhesive properties were first described by Lehr et al. (1992b) demonstrating that chitosan in the swollen state is an excellent mucoadhesive polymer in the porcine intestinal mucosa and is also suitable for repeated adhesion. The authors also reported that chitosan undergoes minimal swelling in artificial... 

Kumar, T.M., Paul, W., Sharma, C.P., Kuriachan, M.A., 2005. Bioadhesive, pH responsive micromatrix for oral delivery of insulin. Trends in Biomaterials and Artificials Organs 18, 198-202. 

The PVA hydrogels have been used for a number of biomedical and pharmaceutical applications, due to its advantages such as nontoxic, noncarcinogenic, and bioadhesive characteristics with the ease of processing. In addition to blood contact, artilicial kidney, and drug delivery applications (39-41), PVA show potential applications for soft tissue replacements (42), articular cartilage (43), artificial organs (44), and membranes (45). 

Bioadhesives exhibit a certain number of characteristics that make them differ greatly from artificial adhesives. They show a sensitivity to - and critical dependence on - the presence of humidity, forming strong bonds under water. They make a recurrent use of molecular constituents, such that widely variable properties are attained from apparently similar elementary units. The non-specific nature of most bioadhesives is remarkable they are able to form sound attachments with a wide diversity of substrates, irrespectively from the presence of detritus, humidity, or the roughness of the surface. Other interesting characteristic is that properties of... 

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