Bioadhesion

Biofllms may be formed on the surfaces of implanted artificial organs, synthetic blood vessels, joint replacements, and indwelling catheters. The picture shows a cardiac assist device. Infection may occur during operation or via the prosthetic conduits. 

Because of the high resistance against antibiotics and chemotherapy, biofilm-associated infections usually lead to recurrent inflammation. Reoperation may be necessary, but inflammation could also result in osteomyelitis, amputation, or even death. The development of longer-term performing synthetic implants, showing reduced infectious complications, requires full understanding of bacterial adhesion. 

One of the most relevant, if not the most relevant, coUoidal and interfacial phenomenon in life sciences is bioadhesion, that is, the joining together of surfaces of which at least one is of biological nature. Usually, bioadhesion involves the association of a biological cell (including bacterial cells) with the surface of a living or an inanimate substratum. In the special case where the adhesion is between particles of comparable size, it may be referred to as aggregation, and adhesion at a gas-liquid interface is also called flotation. 

Most of the cell adhesion concerns microorganisms. In natural environments, about 99% of bacterial mass exists at surfaces, which seems to imply that the association with surfaces is beneficial. Indeed, microorganisms may adhere to survive. To mention a few examples (1) in aquatic systems, nutrients tend to accumulate at surfaces and this is a good reason for microorganisms to adhere there as well (2) microorganisms may adhere to surfaces to avoid transport by flow to a hostile environment, for instance, from the oral cavity into the gastrointestinal tract and (3) in the adhered state, the microorganisms are less susceptible to environmental attacks, such as by antibiotics and chemicals. 

cell adhesion occurs for various reasons and in different appearances. As surfaces of living systems are involved, specific recognition mechanisms undoubtedly 

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The use of a bioadhesive, polymeric dosage form for sustained dehvery raises questions about swallowing or aspirating the device. The surface area is small, and patient comfort should be addressed by designing a small (less than 2 cm ), thin (less than 0.1 mm (4 mil) thick) device that conforms to the mucosal surface. The buccal route may prove useful for peptide or protein dehvery because of the absence of protease activity in the sahva. However, the epithelium is relatively tight, based on its electrophysiological properties. An average conductance in the dog is 1 mS/cm (57) as compared to conductances of about 27 and 10 mS/cm in the small intestine and nasal mucosa, respectively (58,59) these may be classified as leaky epitheha. 

V. Lenaerts and R. Gumy, eds.. Bioadhesive Drug Delivery Systems, CRC Press, Inc., Boca Raton, Fla., 1990. 

Chitosan acetate and lactate salt films have been tested as wound-healing materials. Mechanical, bioadhesive and biological evaluation of the films were carried out. The results were compared to Omiderm . Chitosan lactate exhibited a lower tensile strength, however, it was more flexible and bioadhesive than chitosan acetate. Chitosan lactate and Omiderm did not cause any allergic reactions in contrast, chitosan acetate produced skin irritation clearly due to the anion. Nevertheless, no sign of toxicity was encountered when the extracts of three preparations were administered parenterally [244]. 

Deacon MP (1999) Polymer Bioadhesives for Drug Delivery. PhD Thesis, University of Nottingham, Nottingham, UK... 

A number of the water-soluble polymers also have adhesive properties which are being extensively evaluated for drug delivery (9). These polymers will adhere to the mucous coating in the gastrointestinal tract, the nose, and the mouth to delay passage and sustain drug release. Those polymers with the best adhesive properties are those with hydroxyl and carboxyl groups. Table II lists some of the bioadhesive polymers and their adhesive properties. 

Table II. Examples of Polymers with Bioadhesive Properties...

Bioadhesion-Possibilities and Future Trends Gurney, R. Junginger, H. E., Eds. Wissenscheftliche Verlagsgesellachaft mbh, Stultgart Germany, 1990, pp. 13-213. 

Another approach is that of bioadhesive materials. The principle is to administer a device with adhesive polymers having an affinity for the gastric surface, most probably the mucin coat [12]. Bioadhesives have demonstrated utility in the mouth, eye, and vagina, with a number of commercially available products. To date, use of bioadhesives in oral drug delivery is a theoretical possibility, but no promising leads have been published. 

Bioadhesive Drug Delivery Systems Fundamentals, Novel Approaches, and Development, edited by Edith Mathiowitz, Donald E. Chickering III, and Claus-Michael Lehr... 

HW Hui, JR Robinson. (1985). Ocular delivery of progesterone using a bioadhesive polymer. Int J Pharm 26 203-213. 

In the gastrointestinal tract, a mucoadhesive drug delivery system provides advantages in prolonging the residence time of devices. The use of pH-sensitive bioadhesive polymers has been proposed [26], An extensive review of pH-sensi-tive hydrogels is given by Brpndsted and Kopecek [27],... 

PK Gupta, S-H Leung, JR Robinson. Bioadhesive/mucoadhesives in drug delivery to the gastrointestinal tract. In V Lenaerts, R Gurny, eds. Bioadhesive Drug Delivery Systems. Boca Raton, FL CRC Press, 1990, pp 65-92. 

A. A., Ozalp, M., Wilson, C. G., Formulation of a bioadhesive bilayered buccal tablet of natamydn for oral candidiasis, Proc. Inti. Symp. Control. Rd. Bioact. Mater. 2000, 27, 8205. 

Matthew V. Tirrell (Co-Chair) is Dean of the College of Engineering at the University of California at Santa Barbara. He was previously Professor and Head of the Department of Chemical Engineering and Materials Science at the University of Minnesota, where he served as Director of its Biomedical Engineering Institute. He received a B.S. from Northwestern University and a Ph.D. from University of Massachusetts. His interests are in transport and interfacial properties of polymers, with particular emphasis on molecular-scale mechanical measurements, bioadhesion, and new materials development. He is a member of the National Academy of Engineering. 

Besides widening the clinical use, the research on rifaximin is also focused on the synthesis of new derivatives [173, 273] and on the development of original formulations, like soft capsules [274] and a gum-like device [275], designed for the controlled and continuous release of rifaximin. The former preparation, being bioadhesive, could be particularly useful in the Helicobacter eradication from the stomach whereas the latter should make the treatment of infections of the oral cavity possible, thus expanding the spectrum of clinical use. 

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