Drug encapsulation and release with a nonionic amphiphilic calix[4]pyrrole

A polyethylene glycol-tethered amphiphilic calix[4]pyrrole compound (C4P-PEG) was synthesized via an esterification reaction between the corresponding alcohol-functionalised calix[4]pyrrole and carboxylic acid ended polyethylene glycol. The structure of C4P-PEG was confirmed by means of NMR spectroscopy and high-resolution mass spectrometry. The complexation ability of the control compound octamethylcalix[4]pyrrole and C4P-PEG with chemotherapeutic cancer drug, doxorubicin-HCl, was shown with the aid of various NMR techniques in DMSO, containing 1.5% (wt) water. Nonionic amphiphilic calix[4]pyrrole compound C4P-PEG was then shown to produce stable micelles in water. The title compound was also used to encapsulate doxorubicin-HCl in aqueous medium and its concurrent drug release ability was illustrated under acidic and basic conditions. While the characterizations of drug-free and drug-loaded micelles were carried out with dynamic light scattering experiments and transmission electron microscopy, the drug loading capacity, encapsulation efficiency and in vitro drug release profiles were studied with the aid of UV-vis spectrophotometry.