Method for maintaining stability of the chromogen substrate TOOS
Chromogen substrate TOOS reagent, the chemical name is N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3-methylaniline sodium salt, or 3-(N-ethyl-tolylinyl) Sodium -2-hydroxy-propanesulfonate is the core color reagent in the enzymatic photometric determination of biochemical kits. The color reaction directly affects the sensitivity of detection, so the stability of the substrate and enzyme is very important.
Preservation of the chromogen substrate TOOS
The premise that TOOS can produce color reaction is that it cannot be oxidized in advance during storage, otherwise it may cause low test results. Take Desheng’s TOOS reagent as an example. The finished products are all made into solid powder form and stored in a sealed and opaque brown bottle at low temperature, so that the TOOS powder will not be slowly oxidized by air due to long-term storage, and it will not be Deterioration after high temperature or sunlight.
Chromogen substrate TOOS powder
TOOS is used in dry and wet chemical methods
The chromogen substrate TOOS has a high molar absorbance, so the sensitivity of color development is also very high. In addition to being used in wet chemical methods (solutions), it can also be used in dry chemical methods. The TOOS reagent, coupled 4-AAP and required enzymes (HRP, etc.) can be immobilized on the membrane carrier. After dropping the sample, H2O2 is generated, which then releases new ecological oxygen, oxidizes the color substrate, and passes through the amount of the reaction product. To indirectly determine the target component. It should be noted that both TOOS and enzymes have poor stability due to the influence of temperature, pressure, and light in dry chemical methods. In wet chemical methods, enzymes are easily inactivated when they are in a liquid state or at low concentrations.
The chromogen substrate TOOS improves stability:
1. Protective agents for the color-developing substrate TOOS can be added, such as surfactants and flavonoid pigment substances with an alkyl group with 8 to 16 carbon atoms, but the formula is complicated and interferes with the test. By using a variety of enzymes such as ALT, AST, LDH, ALP, CK in aqueous solution or serum matrix, the stability of the enzyme is improved, and the effect of dry chemical test paper is not significant.
2. Add a protective agent that is more reducible than the color-developing substrate TOOS, but the added protective agent contains primary amino groups and often causes non-specific reactions. Some add sodium citrate, which has a reducing effect, to have a certain effect on the antioxidant of TOOS.
There are many ways to improve the stability of the chromogen substrate TOOS and enzymes by adding protective agents, but it is not a perfect solution to the problem. According to Desheng's experience, this type of reagent should be prepared temporarily during use as much as possible, and should not be prepared as a solution for storage.
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.