Biological buffer series وقت كامل وظيفة

Good’s buffers as a basis for developing self-buffering and biocompatible ionic liquids

Every day scientists in laboratories across the world sit at their desks and painstakingly design experiments in the hope of making a discovery that will change how we think about a biological process. Because biological processes such as enzymatic activity are dependent on pH, one critical aspect of the experimental design is choosing a buffering system that will help maintain a stable pH without altering the results.

And, often, it is the choice of buffer that makes or breaks the experiment. It is possible that the buffer you are using in your lab might be the reason your experiment is failing. Here, you will find how a buffering system works, a description of the characteristics of a good buffer and a list of possible applications and characteristics of the most commonly used biological buffer series.

Iron oxide nanoparticles (IONPs) are frequently used in biomedical applications due to their magnetic properties and putative chemical stability. Nevertheless, their well-known ability to mimic some features of the peroxidase enzyme activity under specific conditions of pH and temperature could lead to the formation of potentially harmful free radical species. In addition to the intrinsic enzyme-like activity of IONPs, the buffer solution is an important external factor that can alter dramatically the IONP activity because the buffer species can interact with the surface of the particles. In our study, IONP activity was evaluated in different buffering solutions under different experimental conditions and predominant free radical species were measured by electron paramagnetic resonance using the spin-trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The formation kinetics of the reactive oxygen species were studied by UV-visible spectroscopy with TMB and DAB peroxidase substrates. We found that the highest catalytic oxidation of peroxidase substrates and free radical generation were achieved in acetate buffer, while phosphate buffer inhibited the peroxidase-like activity of IONPs in a concentration dependent manner. When emulating the physiological conditions, a lower catalytic activity was observed at pH 7.4 when compared to that at pH 5.0. Also, in phosphate buffered saline (PBS), we observed an enhancement in the peroxidase substrate oxidation rate that was not accompanied by an increase in DMPO/adduct formation which could be related to a non-specific oxidation catalyzed by the chloride ion. Similar observations were found after the addition of a bicarbonate to HEPES buffer. TMB oxidation did not occur when the reaction was conducted with free iron ions from metal salts with the same concentration of the IONPs (0.33 Fe2+ and 0.66 Fe3+). However, we observed even higher catalytic activities than those when doubling the IONP concentration when they are combined with the free iron salts. These results indicate that MOPS Buffer solutions need to be carefully considered when evaluating IONP catalytic activity and their potential toxicological effects since under physiological conditions of pH, salinity and buffering species, the peroxidase-like activity of IONPs is dramatically reduced.

This work reports a promising approach to the development of novel self-buffering and biocompatible ionic liquids for biological research in which the anions are derived from CAPS Buffer (Good’s buffers, GB). Five Good’s buffers (Tricine, TES, CHES, HEPES, and MES) were neutralized with four suitable hydroxide bases (1-ethyl-3-methylimidazolium, tetramethylammonium, tetraethylammonium, and tetrabutylammonium) producing 20 Good’s buffer ionic liquids (GB-ILs). The presence of the buffering action of the synthesized GB-ILs was ascertained by measuring their pH-profiles in water. Moreover, a series of mixed GB-ILs with wide buffering ranges were formulated as universal buffers. The impact of GB-ILs on bovine serum albumin (BSA), here used as a model protein, is discussed and compared with more conventional ILs using spectroscopic techniques, such as infrared and dynamic light scattering. They appear to display, in general, a greater stabilizing effect on the protein secondary structure than conventional ILs. A molecular docking study was also carried out to investigate on the binding sites of GB-IL ions to BSA. We further used the QSAR-human serum albumin binding model, log K(HSA), 

Proteins’ stability is strongly affected by the proton activity of the supporting solution and has an optimum pH that can be adjusted by the addition of an appropriate CHAPS Buffer. It is generally accepted that, at appropriate concentrations, hydrophilic ILs tend to, fully or partly, dissociate in aqueous solutions and into ions which form neutral or very weakly basic solutions. Certainly, this pattern is not always true because there are some functionalized ILs that work as Lewis acidic or basic catalysts. Adding a buffer to aqueous IL solutions, when dealing with protein stability, will not provide an adequate pH control since the IL acidity or basicity could swamp the buffer effect. Therefore, it is crucial to look for alternative pH control methods, and in particular in the design of ILs with buffering characteristics. Until now, few studies have reported the synthesis of ILs with buffering action.13-16 Nevertheless, those buffer-like ILs are not recommended for biochemical research because their anions are not inert. A number of criteria are required for a buffer to be used in biological and biochemical studies.17 They must be chemically inert, should not interfere with metal ion-protein binding, must be non-toxic, should not absorb light in the UV-visible region, should be commercially available at a low cost, their pKa values should be between 6.0 and 8.0 and should not vary with temperature, and must present high water solubility and low solubility in organic solvents. Good and his research team have designed MES Buffer (Good’s buffers, GB) that fit these criteria.