Several criteria to consider when choosing a biological buffer
The simplest definition of biological buffer is a solution that can resist changes in hydrogen ion concentration caused by internal and environmental factors. The function of the buffer is to maintain the pH of the system. The effective buffer range of the buffer depends on the dissociation constant pKa of the weak acid in the buffer system. Many factors, such as changes in temperature or concentration, will affect the pKa of the buffer.
In 1966, Norman Goode and his colleagues began to define several practical buffers for biochemical systems. By 1980, Goode and his colleagues discovered 20 buffers that set the standard for biological and biochemical research applications. Goode proposed several criteria for selecting biological buffers.
1. The pKa is between 6 and 8. The optimal pH value for most biochemical experiments is between 6 and 8. The optimal buffer range of the buffer is the dissociation constant of the weak acid component (pKa) in the buffer plus or minus pH unit.
2. Solubility in water. In most cases, biological reactions occur in an aqueous environment, so the buffer should be water-soluble.
3. The repulsive effect of biofilms. This is not important for all biochemical reactions. However, if this is an important criterion for your particular experiment, it is helpful to remember that zwitterionic buffers (positive and negative charges on different atoms in the molecule) will not pass through biofilms. Examples of zwitterionic buffers include MOPS and HEPES; Tris and phosphate buffers do not isomerize to zwitterions.
4. Less salt influence. In other words, the components of the buffer should not interact or affect the ions involved in the biochemical reaction under study.
5. Temperature and concentration changes have little effect on dissociation. Generally, as the concentration changes, there will be some changes in dissociation. If this change is small, you can usually dilute the stock solution without changing the pH of the buffer. However, changes in the concentration of some buffers will produce more drastic changes in pKa, and the stock solution cannot be diluted without significantly affecting the pH value. For example, if you prepare a Tris buffer with a pH of 7.0 in a cold room at 4.0°C and perform the reaction in the same buffer at 37°C, the pH will drop to 5.95.
6. There is no interaction with mineral cations. If the buffer in the system reacts with cations, the effectiveness of the buffer will be reduced because it cannot handle the additional hydrogen ions. If a complex between the buffer and the desired cofactor (metal cations such as zinc or magnesium) forms, your response may also be affected. For example, using an excessive amount of chelating agent in an enzymatic reaction may cause problems (for example, high EDTA concentration in PCR amplification).
7. Chemical stability. The buffer should be stable and will not decompose under working conditions. It should not be oxidized or affected by the system in which it is used. Try to avoid using buffers containing response participants (for example, metabolites).
8. Light absorption. The buffer should not absorb ultraviolet light of a wavelength that can be used for photometric experiment readings.
9. Easy to use. The buffer components should be easy to obtain and prepare.
The above are the 9 points listed by Goodrow to consider when choosing a biological buffer. No matter which buffer you choose, you need to consider the impact of temperature and environment on the buffer, and make sure that the buffer you choose is the same as yours. Compatible with the system. As a professional manufacturer of biological buffers, Desheng has many years of research and development experience, supported by a more professional technical team, and has the ability to provide customers with products with more favorable prices and better quality.
HEPES, as a zwitterionic buffer, increases the osmotic pressure of the cell culture system by increasing the concentration of solution ions, maintaining normal cell morphology and function, and improving cell survival rate. Widely used in cell culture, especially under specific conditions such as tumor cell culture, it is crucial to maintain cell growth and function.