“…Many previously reported efforts have focused on the synthesis of dyes for cysteine detection, with at least 24 synthetic dye-based reported to function in detecting cysteine in the past five years (Table 2) [ 257 , 258 , 259 , 260 , 261 , 262 , 263 , 271 , 272 , 273 , 274 , 275 , 276 , 277 , 278 , 279 , 280 , 281 , 282 , 283 , 284 , 285 , 286 , 287 , 288 ]. Of these, several can be targeted to the mitochondria [ 262 , 282 , 285 , 286 ], the Golgi apparatus [ 259 , 276 ], the endoplasmic reticulum [ 274 , 275 ] and the lysosome [ 277 ]. Five act as non-specific sensors, detecting cysteine and other molecules that contain thiol groups or cysteine metabolites, with some using different wavelengths to distinguish between the different ligands [ 258 , 271 , 273 , 280 , 283 ].…”