Off-the-shelf, prêt-à-porter multianalyte sensing systems are based on the ability of cell-penetrating peptides (CPPs; see picture, blue) to mediate the export of hydrophilic anions (yellowgreen) from lipid bilayer vesicles (gray). Covalent capture of hydrophobic analytes (black) with hydrophilic anions (red) produces amphiphilic anions that can activate CPPs.