Cy-OH-LP is a probe used for detecting lipid-associated hydroxyl radicals through fluorescence and photoacoustic signals. In the presence of hydroxyl radicals, Cy-OH-LP oxidizes to Cy7. Due to Cy7's lipophilicity, it emits weak fluorescence and photoacoustic signals in aqueous environments but strong signals in lipid-rich conditions. Cy-OH-LP is suitable for in vivo photoacoustic imaging of hydroxyl radicals.