Polyelectrolyte capsules packaging BSA gels for pH-controlled drug loading and release and their antitumor activity

Polyelectrolyte multilayer capsules, promising candidates for multifunctional drug delivery systems, have recently received increased interest. However, the low encapsulation efficiency of drugs and the lack of reports about animal experiments have greatly slowed down their development for drug delivery. Here, a polyelectrolyte multilayer capsule filled with bovine serum albumin gel (BSA-gel-capsule) was constructed by a layer-by-layer assembly technique and thermally induced gelation of BSA. Owing to the charge variability of BSA with change in pH, BSA-gel-capsules not only showed a pronounced accumulation effect of drugs into capsules, but also displayed excellent pH-controlled loading and release properties. Moreover, a remarkable targeting action to the lung was discovered after intravenous injection of fluorescein isothiocyanate (FITC)-labeled BSA-gel-capsules into mice. After treatment with doxorubicin-loaded BSA-gel-capsules, effective cytotoxicity against B16-F10 cells and inhibition of the pulmonary melanoma growth were revealed. This paper introduces a new type of smart microstructure with notable pH-responsive ability. This material renders feasible the intravenous administration of polyelectrolyte microcapsules, which will be a big step towards their application as drug delivery vehicles.