Physicochemical cell surface properties

Bendinger, B., Rijnaarts, H. H. M., Altendorf, K. and Zehnder, A. J. B. (1993). Physicochemical cell-surface and adhesive properties of coryneform bacteria related to the presence and chain-length of mycolic acids, Appl. Environ. Microbiol., 59, 3973-3977. 

The presence of soil complicates metal removal because soils sorb metals strongly and can also affect microbial—metal complexation. Walkeretal. (1989) showed that purified preparations of cell walls from Bacillus subtilis and Escherichia coli (423 to 973 mmol metal/g cell wall) were more effective than either of two clays, kaolinite (0.46 to 37 mmol metal/g clay), or smectite (1 to 197 nmol metal/g clay), in the binding of seven different metals. However, in the presence of cell-wall/clay mixtures, binding was reduced. In summary, there are several parameters that affect metal complexation. These include specific surface properties of the organism, cell metabolism, metal type, and the physicochemical parameters of the environment. 

Another challenge is the delivery of a biopharmaceutical to its site of action, as the injection of molecules in solution leads to a partitioning of the molecules according to their physicochemical properties. One approach to deliver particles injected intravenously is based on the concept of differential protein adsorption. After injection the particles adsorb blood proteins according to physicochemical surface properties of the particles. The adsorbed proteins determine the cells to which the particles will be directed (Muller and Keck, 2004). 

Figure 1 shows the physicochemical surface methods used extensively in our laboratory to assess the interfacial structure and properties of predominantly protein substrates like skin, collagen, and living cell surfaces and also to assess the initial sequence of events at clean solid substrates upon their exposure to blood, saliva, and sea water. 

Microorganisms have a complex cell envelope structure. Their surfaces charge and their hydrophobicity cannot be predicted, only experimentally determined [131]. Several microorganisms are not hydrophobic enough to be floated. They need collectors, similar to ore flotation. In cultivation media proteins which adsorb on the cell surface act as collectors. The interrelationship between cell envelope and proteins caimot be predicted, only experimentally evaluated. The accumulation of cells on the bubble surface depends not only on the properties of the interface, proteins and cells, but on the bubble size and velocity as well [132]. On account of this complex interrelationship between several parameters, prediction of flotation performance of microbial cells based on physicochemical fundamentals is not possible. Therefore, only empirical relationships are known which cannot be generalized. Based on the large amount of information collected in recent years, mathematical models have been developed for the calculation of the behavior of protein solutions and particular microbial cells. They hold true only for systems (e.g. BSA solutions and particular yeast strains) which are used for their evaluation. In spite of this, several recommendations for protein and microbial cell flotation can be made. 

The physicochemical and carbohydrate-binding properties of succinylated wheat-germ agglutin have been compared with those of the unmodified lectin.The dramatic decrease in the apparent number of cell-surface receptors detected using the modified lectin is discussed on the basis of a decrease in the isoelectric point of the lectin and in terms of the acidic properties of the cell surface. 

The uptake is preceded by the interaction of the particles with the cell surface. Therefore, the nature of the polymer, mainly the hydrophobic or hydrophilic balance and the surface charge, will affect the uptake process to a large extent. Physicochemical properties of particles govern their rate of uptake from the intestinal tract. The two main deciding factors are the size and the nature of the polymer used to make the particles. 

It is clear that the surface properties of substances, which in the form of particulate matter cause lung injuries play an exceedingly important role in the development of the lesions. Thus the preparation of the material to be tested must not alter the physicochemical properties at the interface of the material with its environment before getting in contact with cells and tissues. 

Sauvet AL, Fouletier J, Gaillard F, Primet M (2002) Surface properties and physicochemical characterizations of a New type of anode material, Lai xSrxQ.i yRUy03 g, for a solid oxide fuel cell under methane at intermediate temperature. J Catal 209 25-34... 

The wealth of information obtained on the general principles of crystalline bacterial cell surface layers, particularly on their structure, assembly, surface, and molecular sieving properties have revealed a broad application potential. Above all, the repetitive physicochemical properties down to the subnanometer-scale make S-layer lattices unique self-assembly structures for functionalization of surfaces and interfaces down to the ultimate resolution limit. S-layers that have been recrystallized on solid substrates can be used as immobilization matrices for a great variety of functional molecules or as templates for the fabrication of ordered and precisely located nanometer-scale particles as required for the production of biosensors, diagnostics, molecular electronics, and nonlinear optics [2,3,6]. 

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