Miltenyi Biotec, Bergisch Gladbach, Germany, has developed Viobility dyes for the verification of and differentiation between living and dead cells. The dyes react with the primary amino groups of proteins and can permeate the weakened cell membranes of apoptotic and dead cells. The fluorescent staining of dead cells is therefore up to 50-fold brighter than the staining of living cells. This makes it possible to measure the viability of a cell by using a flow cytometer, regardless of whether fixed or unfixed cells are analyzed. According to the company, the dyes do not have any toxic effects on living cells, and minimize spillover into other fluorescence channels. All three dyes are available in quantities sufficient for 100 or 500 tests. For more information, visit Miltenyi Biotec.