Oxidative stress, a state in which intra- or extracellular
oxidant production outweighs the antioxidative capacity, lies at the basis of many diseases. DCFH2-DA (2',7'-dichlorodihydrofluorescein diacetate) is the most widely used fluorogenic probe for the detection of general oxidative stress. However, the use of DCFH2-DA, as many other fluorogenic redox probes, is mainly confined to the detection of intracellular oxidative stress in vitro. To expand the applicability of the probe, an alkaline hydrolysis and
solvent extraction procedure was developed to generate high-purity DCFH2 (2',7'-dichlorodihydrofluorescein) from DCFH2-DA using basic laboratory equipment. Next, the utility of DCFH2 was exemplified in a variety of cell-free and in vitro redox assay systems, including
oxidant production by transition metals,
photodynamic therapy, activated macrophages, and platelets, as well as the antioxidative capacity of different
antioxidants. In cells, the concomitant use of DCFH2-DA and DCFH2 enabled the measurement and compartmentalized analysis of intra- and extracellularly produced
oxidants, respectively, using a single read-out parameter. Furthermore, hepatocyte-targeted
liposomes were developed to deliver the carboxylated derivative, 5(6)-carboxy-DCFH2, to hepatocytes in vivo.
Liposome-delivered 5(6)-carboxy-DCFH2 enabled real-time visualization and measurement of hepatocellular
oxidant production during liver
ischemia-reperfusion. The liposomal 5(6)-carboxy-DCFH2 can be targeted to other tissues where oxidative stress is important, including
cancer.