Dimethyl Sulfoxide: An Ideal Electrochemical Probe for Hydroxyl Radical Detection

In situ and real-time determination of hydroxyl radicals ((OH)-O-center dot) in physiological and pathological processes is a great challenge due to their ultrashort lifetime. Herein, an electrochemical method was developed by using dimethyl sulfoxide (DMSO) as a trapping probe for rapid determination of (OH)-O-center dot in aqueous solution. When DMSO reacted with (OH)-O-center dot, an intermediate product methane sulfinic acid (MSIA) was formed, which can be electrochemically oxidized to methanesulfonic acid (MSA) on the glassy carbon electrode (GCE), resulting in a distinct voltammetric signal that is directly proportional to the concentration of (OH)-O-center dot. Other commonly encountered reactive oxygen species (ROS), including hypochlorite anions (ClO-), superoxide anions (O-2(center dot-)), sulfate radicals (SO4 center dot-), and singlet oxygen (O-1(2)), have showed no interference for (OH)-O-center dot determination. Thus, an electrochemical method was developed for the determination of (OH)-O-center dot, which exhibits a wide linear range (0.4-5120 mu M) and a low limit detection of 0.13 mu M (S/N = 3) and was successfully applied for the quantification of (OH)-O-center dot in aqueous extracts of cigarette tar (ACT). Alternatively, the same reaction mechanism is also applicable for the determination of DMSO, in which a linear range of 40-320 mu M and a detection limit 13.3 mu M (S/N = 3) was achieved. The method was used for the evaluation of DMSO content in cell cryopreservation medium. This work demonstrated that DMSO can serve as an electrochemical probe and has valuable application potential in radical study, biological research, and environmental monitoring.