Fluorescence-based chemical tools for monitoring ultrasound-induced hydroxyl radical production in aqueous solution and in cells

Abstract

Hydroxyl-radical (˙OH) responsive fluorescent probes (Umb-DHB and Res-DHB) were developed that utilise the 3,5-dihydroxybenzyl (DHB) functionality. Res-DHB responded to ultrasound-induced hydroxyl radical production in solution and in cells.

Enhancement of sonochemical production of hydroxyl radicals from pulsed cylindrically converging ultrasound waves

“…During the preparation of the Res-DHB samples, we used PBS to maintain the pH of the reactants throughout the reaction. Res-DHB was shown to be stable in PBS and temperature insensitive at 60 C, which is below the temperature rise under the ultrasonic irradiation with SonoCYL at the maximum power output (SI Figure S10 ) [11] . Before every sonochemical reaction, the reaction vessel was saturated with gas ( i.e.…”

“…Moreover, the three dosimetry assays require the chemical concentration in the range of milli-molar, which is not ideal in the detection of very low concentrations of HO• [12] . Here, we quantified the HO• yield by chemical dosimetry with resorufin-DHB (Res-DHB), a highly sensitive, temperature independent, and selective probe for HO• [11] . Similar to TA, Res-DHB proceeds with HO• via an arene hydroxylation reaction mechanism, which is selective to HO•.…”

“…A stock phosphate buffer saline (PBS) was prepared by dissolving one PBS tablet into 200 mL of deionised water (pH 7.4 at 25 °C). The Resorufin-DHB (Res-DHB) compound was synthesised by the schematics ( SI Scheme S2.1 and S2.2 ) according to a recent publication [11] . HO• dosimetry is conventionally conducted by Weissler reaction, Fricke reaction, and terephthalic acid (TA) assay.…”