Frequently Asked Questions - Answers to Reagent Product Issues-He Yuan Li Ji

Q：Do I need to pack and store lentivirus cryovials when using them?

To avoid repeated freezing and thawing of the same virus, which may cause a decrease in titer, it is recommended to pack it separately when using it. During the packaging process, it is necessary to ensure that the operation is carried out in a sterile environment on ice. The packaging volume should be based on the amount of virus used in each experiment, and should not be too small. It is recommended to not be less than 10uL. If the virus after packaging is used for a short period of time, it can be temporarily stored at 4 ℃ (used up within a week). The remaining virus should be stored at -80 ℃ immediately after packaging.
Q：What is the sensitivity of Li Ji's Coomassie Brilliant Blue rapid staining solution?

The sensitivity reaches nanogram level (0.4ng), and a large amount of experimental data shows that this dye solution can color the protein on the gel within 2 minutes, with extremely high sensitivity.
Q：Why is decolorization no longer necessary when using Li Ji Coomassie Brilliant Blue rapid staining solution?

After running the glue, the protein adheres to the glue. If traditional staining solution is used, the entire gel will be stained when staining the protein, so it is necessary to wash off the staining solution on the gel background. Using Li Ji Kaoma, it has strong specificity and only stains proteins, without staining gel, so there is no need for further decolorization.
Q：What are the concentrations of 1xPBS and 10xPBS for Li Ji Biology?

The working concentration of 1xPBS is 0.01M (molar concentration), and the working concentration of 10xPBS is 0.1M (molar concentration)
Q：Do we need to make a standard curve every time we use CCK-8 to measure cell viability?

Suggest doing it every time. Although cells are the same, their states may not necessarily be the same. For cells with different states, it is recommended to perform a standard curve every time.
Q：Is the sensitivity of CCK-8 the same for different cells?

dissimilarity. Suspended cells are more difficult to stain than adherent cells. For adherent cells, the absorbance is generally high after 1-4 hours of cultivation with CCK-8, but for suspended cells, the absorbance may be low. This can be solved by extending the addition time of CCK-8 or increasing the number of cells.
Q：Does the drug affect the determination of CCK-8 during cell drug addition experiments?

1. Note that if the drug has reducing properties (such as vitamin C), it will undergo a color reaction with CCK-8, increasing the absorbance. 2. The metals in the drug have an impact on the color development of CCK-8: when the final concentration is 1mM, lead chloride, iron oxide, and copper sulfate will inhibit 5%, 15%, and 90% of the color development reaction, resulting in a decrease in sensitivity. If the final concentration is 10mM, it will be 100% inhibited. Solution: Firstly, it is necessary to confirm whether the drug has been absorbed. Add CCK-8 to the culture medium containing the drug and measure the absorbance at 450nm. If its absorbance is higher than that of the culture medium without the drug (with CCK-8 added), it indicates that the drug has an effect. The culture medium can be changed before adding CCK-8 to remove the effect of the drug. 3. Due to the possibility of oxidation-reduction reaction substances in the culture medium, it is recommended to use a well for testing before the formal experiment. It is necessary to confirm whether the culture medium and CCK-8 react first. Generally, the normal OD value should be below 0.4.
Q：Why is the repeatability of CCK8 detection data poor?

1. The reagents in the outermost circle of the well plate are prone to volatilization. It is recommended to only add culture medium to the outermost circle of the well and not use it as a measuring well. 2. CCK-8 sticks to the wall. It is recommended to add CCK-8 and gently tap the culture plate to help mix. 3. If there are too many or too few cells, it is recommended to explore the conditions within the range of 1000-100000 cells per well in advance. 4. Bubbles inside the well interfere with the enzyme-linked immunosorbent assay (ELISA) detection. Before detection, it is necessary to ensure that there are no bubbles in each well.
Q：Why is the absorbance value measured by the CCK8 kit low?

1. The number of cells is too low. The number of cells to be tested can be appropriately increased. 2. Staining is difficult, it is recommended to increase the incubation time of CCK-8.
Q：What is the formula for calculating the survival rate of CCK8 cells?

Vitality Calculation: Cell Vitality × (%)=[A (Dosing) - A (Blank)]/[A (0 Dosing) - A (Blank)] × 100 A (Dosing): Absorbance of pores with cells, CCK-8 solution, and drug solution A (Blank): Absorbance of pores with culture medium and CCK-8 solution but no cells A (0 Dosing): Absorbance of pores with cells, CCK-8 solution but no drug solution

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