Polyoxyethylene (10) stearyl ether [Brij <scp>S10</scp>] based niosomal vesicles–fluorescence probing of the microenvironment and applications as drug delivery vehicles

Abstract Nonionic surfactant vesicles (Niosomes) were prepared using a surfactant polyoxyethylene (10) stearyl ether [Brij S10] having a high hydrophile : lipophile balance (HLB). Optical and electron microscopy and light scattering indicate the stability of these vesicles. To propose the niosomal vesicles as future drug delivery systems (DDS), the morphology and bilayer characteristics of the niosomes have to be studied in detail. Insight into the niosomes could be obtained by fluorescence probing of xanthene dye aggregation. The use of Xanthene dye aggregation to probe the vesicular microenvironment has not hitherto been reported. Subsequently, we studied the entrapment and release behavior of these vesicles. The potentiality of these niosomes to entrap and release a real chemotherapeutic drug 5‐fluorouracil (5‐FU) was explored. Niosome‐encapsulated 5‐FU was administered to two breast cancer cell lines: (i) the cell line for aggressive breast cancer, that is, triple negative MDA‐MB‐231 and (ii) the less aggressive ER‐positive MCF‐7. The idea was to test the efficacy of 5‐FU loaded niosomes on a cell with high metastatic potential and another with low metastatic potential. The results indicate a significant cytotoxic effect of 5‐FU entrapped in niosomes on both the cell lines at less than half the IC 50 value of the bare drug alone.