Bioadhesion adhesive characteristics

Such bioadhesive materials were also examined for the controlled release of growth factors and other proteins [77-82]. Of particular interest was the investigation of mucoadhesive PVA gels for use in epidermal bioadhesive systems for the controlled release of epidermal growth factor or ketanserin to accelerate wound healing [78]. Such systems were examined not only for their drug-release properties but also for their strength and adhesive characteristics. 

The bioadhesive characteristics of tablets for oral use made from modified starch, poly(acrylic acid), polyethylene glycol) and sodium carboxymethyl cellulose were recently investigated [406]. In this work, the force and energy adhesion were determined in vitro, and maximum adhesion times were evaluated in vivo in humans [406], In the in vitro, studies, the poly(acrylic add) gave the best performance, however in vivo bioadhesion was not strongly correletated with... 

Along with the physicochemical characteristics of the bioadhesive and mucin pithelium surface, physiological events in the area in which adhesion occurs must be addressed to... 

FTIR spectroscopy has proven to be particularly useful in gaining an understanding of the biocompatibility phenomenon. It is believed [746, 841, 856, 857] that protein adsorption is the initial step in the interaction of blood with implanted biomaterials, followed by adhesion of cells and subsequent tissue attachment. This implies that the substrate surface characteristics influence the process, which was confirmed by ATR studies of albumin adsorption on calcium phosphate bioceramics and titanium [763] and segmented polyurethane [764], albumin and fibrinogen on acetylated and unmodified cellulose [765, 766], poly(acrylic acid)-mucin bioadhesion [767], polyurethane-blood contact surfaces [768], and other proteins on poly(ester)urethane [769], polystyrene [767, 771] and poly(octadecyl methacrylate) [771] and by IRRAS study of adsorption of proteins on Cu [858]. Another branch of IR spectroscopic studies of protein adsorption relates to microbial adhesion (Section 7.8.3). 

The preparation of a bioadhesive drug delivery system based upon gelatin/polyacrylic acid microspheres loaded with a model drug (oxprenolol hydrochloride) is described. The effects of preparation and formulation variables on the physicochemical properties and pharmaceutical characteristics of the microspheres are examined and the in-vitro adhesion, bioadhesion, drug release and drug bioavailability behaviour of the drug delivery system evaluated. 15 refs. 

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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