A method for sorting cells included in a cell population is described. The method includes the step of first exposing the cell population to a biologically active fluorescent peptide containing peptide and light-emitting moieties. A first group of cells in the cell population are then labelled when the peptide of the biologically active fluorescent peptide binds to a corresponding receptor contained on (or in) each cell in the first group of cells. The first group of cells or a group of cells excluding the first group of cells are then sorted from the cell population.
