Considering the repeatability and consistency of the experiment, we usually use the optimal concentration of 2mg/ml, which is merely a constraint to ensure the stability of the experiment. This concentration is not absolutely fixed and can be adjusted according to the actual situation, such as trying to be 1-2 times or 0.5 times around the optimal concentration. -  4mg/ml  Between them, in addition, too high or too low will affect the marking efficiency &" The subsequent usage effect.