Cell based assay or cell assay are those which make use of a cell and its constituents for assay of any compound. These cell based assays are broadly classified as live cell assay (viability assay) and non-live assays. As the name indicates, in viability assay, live cells are used for assay while in non-viable assay, dead cells are used for assay.
Here the cell is live and its ability to survive exposure to adverse chemical substances are studied. Here the compound under test are studied for cytotoxicity as in cancer, cytotoxicity to check effectiveness of antibiotics, antifungal etc. In non-viability assay:
The cells are not live and hence cell constituents from dead cells are considered for analysis. Constituents like glucose, ATP, Nitric oxide, other oxidative radicals are studied to know their physiology or apoptosis causes etc.
Cell viability assay protocol:
1 Cells are grown on suitable nutrition medium in a petridish or a bottle having liquid nutrition medium (broth).
2. After some free and profuse growth and multiplication of cells, the samples under test are placed with impregnation on filter paper disks on the surface of medium or poured into the broth where cells are grown.
3. Then the system is incubated for few days at fixed temperature and humidity with provision of oxygen.
4. Then the zone of inhibition of cell growths on petridish plates or a decline in turbidity of the cells inside the broth are measured. The extent of inhibition or decline are function of the effectiveness of the test compound.
The zone of inhibtion is measured by staining the microbial colony on the petridish plates and viewing them under microscope. The alteration in turbidity in the broth is measured by nephalmetry or turbidometry.
1. Here the dead cells are extracted off for their ATP, nitrogen content.
2. Then their concentration or quantity is estimated using some chemical reactions followed by colorimetry etc..