Brown Zachary E, Soltau Carl P, Marshall David L, Bottle Steven E, Miljevic Branka
School of Earth and Atmospheric Sciences, Queensland University of Technology GPO Box 2434 4001 Brisbane Australia
School of Chemistry and Physics, Queensland University of Technology GPO Box 2434 4001 Brisbane Australia
RSC Adv. 2025 Jul 23;15(32):26395-26402. doi: 10.1039/d5ra03412d. eCollection 2025 Jul 21.
The accurate detection of airborne pollutants remains critical for safeguarding both environmental integrity and public health. Equally important is the consideration of method stability and susceptibility to degradation by common reactive atmospheric species, such as ozone. This study examines the reactivity of ozone towards the profluorescent nitroxide (PFN) BPEAnit, a molecular probe that is used in an acellular assay for detecting reactive oxygen species (ROS) from particulate pollution. Online fluorescence measurements revealed a dose-dependent increase in fluorescence when a BPEAnit/DMSO solution was exposed to low-level ozone concentrations (0-544 ppb). Exposure to excess ozone ( 9.5 ppm) produced sufficient fluorescent products for LC-MS analysis, which, when combined with isotope labelling, enabled structural characterization of several products, accounting for 43.5% of the total fluorescent signal. Under similar conditions the parent fluorophore (BPEA) showed no reactivity toward ozone, confirming the specificity of BPEAnit. The primary mechanism is proposed as a single-electron transfer between BPEAnit and ozone, forming an oxoammonium cation and ozone radical anion, which react with DMSO to yield carbon- and sulfur-based adducts. Increased moisture significantly altered the product distribution, highlighting the need to consider ambient humidity in these atmospheric assays. Preliminary evaluation of alternative solvent systems, ethanol and cyclohexane, revealed simpler reaction profiles with fewer products; however factors such as solvent volatility, ozone dose-response, and product stability require further investigation. These findings support the reliability of the BPEAnit probe towards ozone, as well as demonstrating a sensitive, ozone-responsive fluorescence profile, offering potential for broader application in atmospheric monitoring.
准确检测空气中的污染物对于维护环境完整性和公众健康仍然至关重要。同样重要的是要考虑方法的稳定性以及对常见活性大气成分（如臭氧）降解的敏感性。本研究考察了臭氧与前荧光氮氧化物（PFN）BPEAnit的反应活性，BPEAnit是一种分子探针，用于无细胞分析中检测来自颗粒物污染的活性氧（ROS）。在线荧光测量显示，当BPEAnit/二甲基亚砜（DMSO）溶液暴露于低浓度臭氧（0 - 544 ppb）时，荧光呈剂量依赖性增加。暴露于过量臭氧（9.5 ppm）产生了足够的荧光产物用于液相色谱 - 质谱（LC - MS）分析，结合同位素标记，能够对几种产物进行结构表征，这些产物占总荧光信号的43.5%。在类似条件下，母体荧光团（BPEA）对臭氧无反应性，证实了BPEAnit的特异性。提出的主要机制是BPEAnit与臭氧之间的单电子转移，形成氧鎓阳离子和臭氧自由基阴离子，它们与DMSO反应生成基于碳和硫的加合物。水分增加显著改变了产物分布，突出了在这些大气分析中考虑环境湿度的必要性。对替代溶剂系统乙醇和环己烷的初步评估显示反应谱更简单，产物更少；然而，诸如溶剂挥发性、臭氧剂量响应和产物稳定性等因素需要进一步研究。这些发现支持了BPEAnit探针对臭氧的可靠性，同时展示了一种灵敏的、对臭氧有响应的荧光谱，为在大气监测中的更广泛应用提供了潜力。
