Resumen:
ggregation phenomena of Neutral Red and a new derivative monobrominated Neutral Red were
examined in different buffer solutions as a function of dye concentration. The dyes were chemically and
photochemically stable and the lipophilicity of the new bromo-compound was characterized by experimental
and computer prediction data. In addition, the acid dissociation constant and the singlet molecular
oxygen production were determined spectrophotometrically yielding values of 1.16 and 3.14 for
Neutral Red and the monobrominated derivative, respectively.
The effect of photosensitizer concentration, visible irradiation time and cellular density on lethal
photosensitization against Staphylococcus aureus were investigated. The improved physicochemical and
photophysical properties of monobrominated Neutral Red were accompanied by a significant increase in
the photoantimicrobial action, in conventional-sensitive and -resistant isolates.
Based on these results, the dyes exhibited favorabl