Comet assay with SYBR® Green I nucleic acid gel stain (Cat. no. S7563, S7567, S7585). DNA fragmentation associated with oxidative DNA damage was visualized using Trevigen's CometAssay kit. HL-60 cells were treated with H₂O₂ and immobilized onto a Trevigen CometSlide for analysis. The cells were gently lysed, washed and treated with endonuclease. Slides were subjected to electrophoresis in alkaline electrophoresis buffer and stained with SYBR® Green I stain.