Bioadhesive-biological interface

The electronic theory is based on the assumption that the mucoadhesive hydrogel and the target biological tissue have different electronic structures. When two materials come into contact with each other, electron transfer occurs, causing the formation of a double layer of electrical charge at the bioadhesive-biological interface. The bioadhesive force is believed to be due to attractive forces across this electrical double layer. 

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. 

Bioadhesion is very complicated from a physical-chemical point of view. Interfacial tensions, wetting, and electrical properties of the surfaces are prominently involved. Because the (aqueous) medium from which the cells adhere usually contains surface-active molecules, notably proteins, the cells adhere as anile onto an adsorbed proteinaceous layer. The preformed adsorbed layer will therefore largely determine the subsequent cell adhesion process. Furthermore, biological cells often carry polymeric substances at their surfaces. These components may influence the interaction with a substratum surface in various ways, as is explained in Section 16.3. Understanding bioadhesion therefore requires a thorough knowledge of various aspects of colloid and interface science. 

Chapter 19 deals with the physicochemical aspects of the most ubiquitous interface in living systems, the biological membrane. We conclude with Chapter 20, which deals with bioadhesion, that is, the accumulation of biological cells at interfaces. Bioadhesion may lead to adverse effects—for example, fouling of surfaces—but in other applications it is desired—for example, immobilization of cells in bioreactors. 

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