Enrichment of liposomal nanomedicines using monolithic solid phase extraction discs following preactivation with bivalent metal ion solutions

Silicate is an excellent adsorbent because of its large surface area and amenability to surface modification. In this study, the representative liposome nanomedicines DOXIL® and AmBisome® were enriched using a silica monolith disc (diameter 4.2 mm, length 1.5 mm) with bimodal pores. Although the nanoparticles passed through the disc without retention when water was used as the preactivation solution, they were strongly retained by the disc when a 1 M bivalent metal (such as Mg2+, Ca2+, and Ni2+) solution was used. Notably, strong affinity was observed to DOXIL, a pegylated liposomal nanoparticle, by the disc composed of 5 μm and 10 nm through- and meso pores, respectively, and nearly 100% of DOXIL was recovered from a 40× diluted solution. Overall, the results demonstrate that monolithic discs are effective for the enrichment of liposomal nanomedicines.