I am interested in using 3,3'-Diaminobenzidine (DAB) in live bacteria(Gram negative). All protocols that I have come across have a fixation step before introducing DAB. My question is whether anyone has tried/ knows if DAB is cell permeable under certain solvent conditions (DMSO, EtOH etc.). The purpose of staining is to observe sites of local singlet oxygen generation. Any inputs will be really appreciated. Thank you in advance!