Biological Solutions

If a catalyst is to work well in solution, it (and tire reactants) must be sufficiently soluble and stable. Most polar catalysts (e.g., acids and bases) are used in water and most organometallic catalysts (compounds of metals witli organic ligands bonded to tliem) are used in organic solvents. Some enzymes function in aqueous biological solutions, witli tlieir solubilities detennined by the polar functional groups (R groups) on tlieir outer surfaces. 

All biological systems contain aqueous electrolyte solutions. These solutions consist of strong electrolytes (inorganic salts) as well as various organic substances with acidic or basic functional groups which usually behave as weak electrolytes. The solutions are often gel-like in their consistency because of the polyelectrolytes, proteins, and other macromolecules contained in them. The pH values of biological solutions as a rule are between 6.7 and 7.6. 

Zaslavsky, B., and Masimov, E. Methods of Analysis of the Relative Hydrophobicity of Biological Solutes. 146, 171-202(1988). 

Strong suppression of matrix effect of complex biological solution on the detection of the one component of interest... 

Abstract This is a short review of how neuronal sensors fit in the broader biological context of animal survival. This may help those involved in the development of engineered sensors to put in perspective their task with what the evolutionary process has achieved. Most of the information reported here is available in the educational field of neuroscience, with mention of some recent relevant findings. I have attempted to place these findings in an evolutionary perspective as it clarifies better the intrinsic role of some of the extraordinary particularities of the biological solutions of neuronal sensors. 

Our research shows that in biological systems energy is, as far as possible, taken from the environment as and when it is needed rather than carried around (e.g. as liquid fuel) and is used to solve only 5% of biological problems, whereas in technology up to 75% of problems need energy to solve them. A far more important factor in the biological solution of problems is information - the genetic sequence, the specific chemistry required the drive specific reaction... 

Problems with reference electrode/electrolyte. The sample solution can react with the electrolyte. The greatest source of error in biological solutions is through the formation of insoluble silver sulfide, often at the ceramic frit. A blackened spot is usually observed in a pH electrode that has been in service for a few weeks. This precipitate can impede the free flow of electrolyte and cause the probe response to become sluggish and cause large errors in the measured pH. 

Patton, C. Thompson, S. Epel, D. Some precautions in using chelators to buffer metals in biological solutions. Cell Calcium 2004, 35, 427-431. 

Technically, one includes solvent as one of the components when expressing mole fraction in chemical thermodynamics, but in describing dilute biological solutions, solvent is oftcn Omitted. With multicomponent solutions, one may chose to analyze the fractional composition of any two (or more) substances while not including others held constant in the experiment (e.g., concentrations of buffer components, proton, supporting electrolyte(s), enzyme, eta). For two components,... 

Each site and material must be evaluated before implementing a biological solution. The soil is examined in chemical laboratories to assess the type and extent of the contamination. The microbiological laboratory analyzes the presence and activity of the local microbial strains in the contaminated soil. Biologists then specify the type and quantity of natural additives required to produce maximum degradation rates. 

Almost every biological solution of low viscosity [but also viscous biopolymers like xanthane and dilute solutions of long-chain polymers, e.g., carbox-ymethyl-cellulose (CMC), polyacrylamide (PAA), polyacrylnitrile (PAN), etc.] displays not only viscous but also viscoelastic flow behavior. These liquids are capable of storing a part of the deformation energy elastically and reversibly. They evade mechanical stress by contracting like rubber bands. This behavior causes a secondary flow that often runs contrary to the flow produced by mass forces (e.g., the liquid climbs the shaft of a stirrer, the so-called Weissenberg effect ). 

Almost every biological solution of low viscosity [but also viscous biopolymers like xanthane and dilute solutions of long-chain polymers, e.g., carboxymethyl-cellulose (CMC), polyacrylamide (PAA), and polyacrylnitrile (PAN)] displays... 

Minimized interaction between eluite molecules and column packing is operative in hydrophobic interaction chromatography where biological solutes are so mildly bound to a stationary phase that their delicate native tertiary structure is not spoiled. This separation of extreme mildness is also a separation of chemically differing species, i.e., separation by composition. 

The range of essential anions is much more limited but it includes chloride, phosphate, carbonate and bicarbonate ions. The first of these is the major anionic species in almost all biological solutions. The other three help to control the pH of body fluids while phosphate is concerned in energytransfer reactions. Trace anions such as iodide and fluoride are also essential. 

Dialysis was also used in the laboratory in the 1950s and 1960s, mainly to purify biological solutions or to fractionate macromolecules. A drawing of the... 

Figure 13.2 Schematic drawing of laboratory dialyzer developed by Craig [4] to separate low-molecular-weight impurities from biological solutions. This was the best method of performing this separation until ultrafiltration membranes became available in the late 1960s. The feed solution was circulated through the inside of the membrane tube solvent solution was circulated on the outside. Boundary layer formation was overcome by rotating the outer shell with a small motor...

Biotic Controls Biological solutions to insect pest problems. For example, application of beneficial insects to control pest populations. 

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