Table 1.

The probes, target ROS, pros, and cons of ROS detection methods.

Detection Methods	Probes	Target ROS	Pros	Cons
Fluorescent Chemicals	Dihydroethidium Dichlorodihydro fluorescein Amplex Red	O2˙− and H2O2	Cell permeation possible Stable products are formed Intensity can be quantified	Formation of complex product Specificity is low Interference occurs by OONO−
Fluorescent Proteins	Green fluorescent proteins (roGFP1, 2, iL, P1-RX), Grx1-roGFP2-iL and roGFP2-Orp1 Yellow fluorescent proteins (rxYFP-Grx1P, rxYFP 3R) HyPer (HyPer-2 and HyPer-3) Circularly permuted green fluorescent protein (cpYFP) HyPerRed (rxRFP), TrxRFP1 and cpRFP	H2O2 and Variation in redox level	Offers real-time and dynamic detection of change in redox level with no special requirement for cell permeability As fluorescent proteins can stay in cell, so allow long term detection of cell radicals Reveals localized redox status Cell friendly	Preparation of these probes is complicated roGFP exhibits low sensitivity Reaction rate of proteins with redox substance is quite low Differential selectivity of roGFP2-Orp1 and HyPer for H2O2 due to different reaction capability may lead to data inaccuracy
Chemi-luminescence	Lucigenin Luminol Luminol analogue	H2O2 and O2˙−	Cell permeation possible	Sensitivity low Selectivity low Unstable intermediates
Electro-chemical Biosensing	Alternate polyaniline-sulfonic acid and Cytochrome-c layers over gold wire electrode	O2˙−	Detection is fast Sensitivity is high	Preparation is complex
Chromatography	DMSO Salicylic acid and Benzoic acid	˙OH	Detection is fast Sensitivity is high	Complex products are formed
Spectro-photometry	Cytochrome c Nitroblue tetrazolium Aconitase Boronates Diaminobenzidine	O2˙− and H2O2	Sensitivity is high Detection is fast Single product is formed	Specificity is low
EPR/ESR	Spin traps	ROS and RNS	Sensitivity is high Specificity is high	More expensive