Table 1. Physical and Chemical Properties of Investigated ROS Sensors^a.

sensor	λex [nm]	λem [nm]	concn [μM]	detected ROS	Φ [Gy–1]	Φ 4h [Gy–1]	ΔΦ%4h	cell permeable
C3C	290	460	350	HO•	0.297	0.211	29	N
DHRh 123	500	530	200	H2O2, ONOO–, NO	0.538	0.307	43	Y
SOSG	500	525	10	1O2	0.314	0.300	4.4	N
AMPLEX REDb	570	585	100	H2O2b	1.55	0.697c	55c	N
DCFH-DA	495	525	100	H2O2, HO•, ROO•	0.12	0.03	74	Y
APF	485	515	10	HO•,ClO–, ONOO–	1.47	0.23	84	Y
ROS-Star 550	546	561	200	HO•, O2•–	0.12			Y

^aΦ, sensor sensitivity; Φ_4h, sensitivity after 4 h; ΔΦ%_4h, relative loss of sensitivity, i.e., instability. Linear regressions used to compute these data are reported in Figure S3. C3C, coumarin-3-carboxylic acid; DHRh 123, dihydrorhodamine 123; SOSG, singlet oxygen sensor green; DCFH-DA, 2′,7′-dichlorofluorescin diacetate; APF, aminophenyl fluorescein.

^bInteraction mediated by horseradish peroxidase (HRP).

^cΦ variation after 2 h only.