Dye-doped droplets are known as mixtures of dyes with uniform solutions of water droplets in a continuous phase of oils with surfactants. To observe the relationship between water droplet structures and surfactant types on optical properties of dyes, a mixture of methyl orange (MO)-doped droplet prepared with benzane and hexane as oils and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as a surfactant was thus examined using Z-scan instrument, spectrophotometer, and fluorimeter in the present study. The findings revealed that nonlinear refractive (NLR) index, nonlinear absorption (NLA) coefficient, as well as fluorescence intensity of theMOhad enhanced following a reduction in the droplet water content induced by changes in the noncentrosymmetric charge density distribution of this pH indicator. Moreover, the MO-doped droplet in a continuous phase of benzene investigated by 1H nuclear magnetic resonance (NMR) spectroscopy indicated that the MO had been located in the droplet in the vicinity of the hydrophilic part of the surfactant. Furthermore, the MO-doped droplets along with laser radiation were employed to perform antibacterial photodynamic therapy (APDT) of Staphylococcus aureus (S. aureus). It was ultimately concluded that the bacteria colony had also extremely diminished in the group treated by the MO-doped droplet.

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