Imaging of liposomal drug delivery systems by atomic force microscopy

Over the past four decades, the research focused in the development of new liposomal drug delivery systems exponentially grew as a result of their proven efficacy in carrying pharmacological active molecules to target specific sites. In fact, the drug loading into liposomes both increases the drug’s bioavailability through the prevention of unfavourable chemical reactions triggered by enzymatic attacks as allows a sustained release. Several studies highlighted that physical characteristics of lipids such as their geometry, size and surface charge strongly influences the encapsulation efficiency as well the in vitro and in vivo stability. These characteristics can be accessed by atomic force microscopy (AFM) as well as the biomechanical properties of liposomes with and without drug encapsulated. In this chapter, the crucial contribution of AFM to study the dynamic behaviour of liposomes is reported, including a discussion about challenges and limitations needed to overcome as the collapse of liposomes induced by the AFM-tip.