Critical Design Factors for Optical Imaging with Metal Coordination Complexes

Metal coordination complexes are emerging as an important class of optical imaging probes. They may function not only as stains for particular cell compartments, but also as responsive probes, able to report on changes in local ionic composition. The critical factors to consider in designing such probes are reviewed, including issues of cell uptake and compartmentalization, the degree of non-invasiveness and their functional performance. Prospects are considered for the development of lanthanide(III) probes capable of reporting changes in local bicarbonate, citrate, and lactate.