2.2. Crystal violet staining analyzed by spectrophotometry
Staining with crystal violet is also often used to measure cell
viability in cell cultures. Like the above mentioned technique, this
staining is typically done in 96-well based assays for analysis of the
concentration gradients of agents that induce cell death or compounds
that inhibit cell death. The principle of this technique is
that crystal violet stains DNA of the remaining attached cells,
because dead detached cells are removed by multiple washing
steps. The repeated washing steps may sometimes cause detachment
of living cells (typically in conditions of higher cell density),
which makes this technique prone to artifacts. This technique has
been used frequently in early years, but nowadays several better
alternatives are available (see Section 3).