Multi-Stimuli Responsive Self-Assembled Nanostructures Useful for Colon Drug Delivery.

Self-assembled nanoformulations have been finding various applications in biomedical sciences. Here, we have designed and synthesized a small molecule-based amphiphilic conjugate of azobenzene, Azo-PEG-OMe, which self-assembles into nanostructures in an aqueous environment. The formation of nanostructures was evidenced by light scattering and electron microscopic analyses, which revealed the size of the so formed nanostructures ~199 and ~42 nm, respectively. Responsiveness of these nanostructures to various stimuli was demonstrated by enzyme and UV-Vis light exposure, pH and chemical reductant, sodium dithionite. Morphological alterations in the nanostructures on exposure to these stimuli were recorded and subsequently, these nanostructures were demonstrated as efficient carrier of drugs by entrapping an antiprotozoan drug, ornidazole, with ~82% entrapment efficiency. Under influence of different stimuli (light, pH, and enzyme), the drug release behavior displayed good response to each stimulus implying that the projected nanostructures could be used as efficient drug delivery system. Response to azoreductase enzyme further established that the formulation can be used for site specific drug delivery particularly useful for colonic drug delivery.