Table 2.
Common Examples of Probes Used to Detect ROS in Cells or In Vivo, Including Small Molecules, Proteins, and Nanostructures
| ROS sensor | Mechanism | Sense | Readouta | Ref. |
|---|---|---|---|---|
| roGFPs | Oxidation of adjacent cysteine residues changes fluor. maximum | GRXs | Ex/Em: 400/490–510 nm | (82, 87, 130) |
| HyPer | Oxidization of adjacent cysteine residues changes fluor. maximum | H2O2 | Ex/Em: 420/500–516 nm | (11, 70, 127) |
| Redoxfluor | Oxidation of cysteines in fragment of yeast redox sensor causes loss of FRET between cerulean and citrine | Redox potential of glutathione | Em ratio 527/476nm | (201) |
| DCFH-DA | Oxidation after esterase-mediated cleavage converts to fluorescent form | ROS | Ex/Em: 485/530 nm | (55) |
| Dihydrocalcein acetoxymethylester | Oxidation after esterase-mediated cleavage converts to fluorescent form | ROS | Ex/Em: 488/515 nm | (93, 152) |
| Hydroethidine (HE) | Forms a red fluorescent product that intercalates with DNA | O2−• | Ex/Em: 518/605 nm | (19, 144, 204) |
| Amplex® red (10-acetyl-3,7-dihydroxyphenoxazine) | Oxidized to resorufin (colorimetric and fluorescent) | H2O2 | Ex/Em: 563/587 nm | (1, 101, 205) |
| Or Abs: 565 nm | ||||
| FOX-2 reagent | Oxidation of iron produces a colored ferric-xylenol orange complex | H2O2 | Abs: 560 nm | (85) |
| Clark's electrode | Electrochemical sensor | H2O2 | Electrochemically | (109, 178) |
| Hydrocyanines | Oxidation generates extended π conjugation | O2−• and HO | hydro-Cy7, Ex/Em: 735/760 nm | (105) |
| Aryl boronic acids and esters | H2O2 cleaves boronate and yields fluorescent or chemiluminescent products | H2O2 | Different generation with different Ex/Em | (43, 49, 132, 185) |
| Peroxalate nanoparticles containing fluorescent dyes | Oxidation of peroxalates generates high-energy dioxetanedione that excites dyes | H2O2 | Em: 460–630 nm | (111) |
| Nanoreactor composed of peroxyoxalate fuel and Cy5 | Oxidation of peroxyoxalate generates high-energy intermediate that excites Cy5 | H2O2 | Em: 698 nm | (115) |
| Hydrocyanine-conjugated, chitosan-functionalized Pluronic-based nano-carriers | Oxidation of hydrocyanine to cyanine | ROS | Ex/Em: 675/693 nm | (95) |
| FOSCY-1 (two linked cyanine dyes) | Oxidation of one dye releases fluorescence quenching of the other | ROS | Ex/Em: 645/668 nm and 771/813 nm | (143) |
Additional examples that detect specific ROS are reviewed by Chen et al. (34), Lu et al. (120), and Freitas et al. (62).
a
Wavelength may vary according to instruments.
DCF, 2′,7′-dichlorofluorescein; DCFH-DA, 2′-7′-dichlorodihydrofluorescein diacetate; GRXs, glutaredoxins; roGFPs, redox-sensitive green fluorescent proteins; ROS, reactive oxygen species.