(23a) Heterogeneous Liposome Assemblies: When Soft Meets Hard (Invited)

Liposomes, lipid bilayer vesicles, are almost routinely used as encapsulating agents for drug delivery. Individual liposomes typically serve as a protection layer that prevents the encapsulated drug from premature release and protects it from the environment. The release of the drug is then relatively slow and spontaneous. Although intensive research is carried on in order to prepare systems that are sensitive to changes in pH, temperature or external stimulus such as sonication or magnetic field, there is still lot of unexplored possibilities.

In our work we have designed liposome-based entities that consist from one or more liposomes as compartments and can contain also iron oxide nanoparticles (MgNPs) for remote control of the aggregate and/or silica nanoparticles to improve the loading capacity. We have tested several different approaches of forming the liposomal aggregates, including use of the alginate microcapsules as liposomes – MgNPs vehicle, charged liposome aggregation due to high ionic strength of the buffer, using DNA amphiphiles as anchors between liposomes, and using polyelectrolytes such as poly-L-lysine as a glue for charged liposomes and MgNPs. This last approach was studied extensively and resulting aggregates, stabilized using the MgNPs, were tested for their ability to follow the magnetic field and to perform remotely triggered release. We have also tested the method of increasing the loading capacity of individual liposomes using porous silica nanoparticles (due to their good sorption properties). Such approach can significantly increase the loading capacity of liposomes and influence their response to external stimulus.