Gemini Surfactant Mediated Catansomes for Enhanced Singlet Oxygen Generation of Rose Bengal and Their Phototoxicity against Cancer Cells

Photodynamic therapy (PDT) is an innovativetechnique for cancer treatment with minimal side effects, based onthe use of a photosensitizer, oxygen, and light. Photosensitizers(PSs) have several limitations, that may limit their clinical use, likepoor solubilization, self-aggregation, and lack of specific targeting,which can be addressed with the use of nanomaterials. Herein, aunique type of catansomes (CaSs) was prepared using a geminiimidazolium-based surfactant (1,3-bis[(3-octadecyl-1-imidazolio)-methyl]benzene dibromide (GBIB) and a double chain surfactant,diaoctyl sodium sulfosuccinate or Aerosol OT (AOT). Theformation of CaS GBIB/AOT was optimized in various ethanol/water (E/W) solvent ratios by employing a facile, quick, and mostreliable solution-solution mixing method. The CaS was charac-terized by dynamic light scattering (DLS) andfield emission gun scanning electron microscopy (FEG-SEM) techniques. Theexperimental results reveal that stable CaSs with a spherical shape were obtained at lower concentration (100 mu M). Rose Bengal(RB), a PS of the xanthene family, was incorporated into these prepared CaSs, as proven byfluorescence spectroscopy, UV-visibleabsorption spectroscopy, and confocal laser scanning microscopy. Singlet oxygen (1O2) generation studies revealed the relevant roleof the E/W solvent ratio as there was a 4-fold boost in the1O2production for GBIB/AOT in E/W = 50:50 and around 3-fold in E/W = 30:70. Also, the GBIB-rich 80:20 fraction was more efficient in increasing the1O2generation as compared to the AOT richfraction (20:80). Further, their phototoxicity was tested in a water-rich solvent ratio (E/W = 30:70) against MCF-7 cells. Uponirradiation with a 532 nm laser (50 mW) for 5 min, RB@GBIB/AOT(20:80) fraction caused 50% decrease in the metabolic activityof MCF-7 cells, and RB@GBIB/AOT(80:20) fraction produced a maximum 85% decrease in cell viability. Furthermore, theenhancement in intracellular1O2generation by RB@GBIB/AOT, as compared to pure RB, was confirmed with singlet oxygensensor green (SOSG). This new type of CaS based on gemini surfactants exhibiting a large amount of1O2generation, holds greatinterest for several applications, such as use in photomedicine in future.