Evaluating the use of 3'-(p-Aminophenyl) fluorescein for determining the formation of highly reactive oxygen species in particle suspensions

Particle-generated hROS can be quantified with an estimated detection limit of 50 nM. Measurements of hROS in two National Institute of Standards and Technology (NIST 2709 and 2710) soil suspensions and a pyrite suspension show non-linear particle dose-response curves for hROS generation. APF can also be used in solutions containing no dissolved molecular oxygen (O2) to determine the role of O2 in the formation of hROS. Results confirm that O2 is mechanistically important in the formation of hROS by dissolved ferrous iron and in pyrite suspensions.Given the non-linear dose-response curves for particle generation of hROS, we recommend using several particle loadings in experiments aimed to compare particles for their hROS generation potential. The method presented here is specific to hROS and simple to perform. The analysis can be conducted in mobile labs as only basic laboratory equipment is required.Hydroxyl radicals are a highly reactive oxygen species (hROS) that reacts non-specifically with most organic molecules within nanoseconds after their formation [1]. In vivo, hydroxyl radicals (？OH) have been implicated in causing oxidative stress [2,3] and several diseases [4,5]. The role of particulate-induced formation of ？OH on inducing lung diseases has been the focus of many studies. Hydroxyl radicals have been directly implicated in lung diseases related to exposures to asbestos [6], silica [7,8], and other airborne particulate matter [9,10] as a result of genotoxicity [7,2] and/or oxidative stress [11,2,12]. Hence, ？OH formation in vitro and in vivo has been used as an indicator for particulate-induced toxicity potential [7,2,11,13,4,15].The mechanisms whereby particles induce the formation of hROS in solution and in vivo are not fully understood, however several pathways are recognized [for a review, see [16]]. In solution, particles containing transition metals may generate ？OH by redox reactions involving metals exposed at the particle surface or by redox reac