Please remember that "plant extract" is really hard do define. Such studies with "extracts" are not easy to validate and reproduce.
Depending on the interaction between the extract constituents you can get different, sometimes conflicting effects. I reviewed many papers in which the authors could not describe their extracts precisely. The most frequent methodological error in these works was the use of extracts that were not standardized in any way. As a result, very interesting works contained a very serious methodical error. It was not possible to repeat them.
In the end, I highly recommend thinking about study with the main component responsible for the expected effect instead "extract" based solutions etc.. Of course, this is only possible if you know which component is responsible for expected pharmacodynamic action.
In an optimistic scenario, two or three constituents of extract that work similarly may be responsible for the expected pharmacodynamic effect. In this case, it is best to obtain (isolate or synthesize) one of them and design further research with one specific substance from extract.
In the worst case, only interaction between many ingredients (prerequisite) is responsible for the PD effect. It may also turn out that none of them will cause the desired effect. In this case, the study of single components is not successful. On the other hand, the study of such an extract has no any application meaning. It is especially important for potential candidates for an anticancer drug. Because in this case, the dosage issues, interaction with other drugs used in drug therapy, personalization of treatment, or pharmacokinetics analysis are not possible for real evaluation.
So my advice is decide in early stage (if is still possible) should you make your studies with solution based on extract, or try work with specific extract constituents after their isolation.
plant extract (nanoparticles form) dissolve nanoparticles to 10 ml RPMI medium on sonicator then make serial dilution ex: Falcon 1 which contain plant extract and medium , Start with 4 falcon tubes each of this contain 9ml medium
first tube : take 1ml of falcon 1 and mix it in first tube
second tube : take 1ml of first tube and mix it in second tube
third tube : take 1ml of second tube and mix it in third tube
forth tube : take 1ml of third tube and mix it in forth tube
then cells will be seed in 96 well plate ,leave it in incubator until cell will be attached , add your dilution of plant extract .