A thermal analysis and physicochemical study on thermoresponsive chimeric liposomal nanosystems

Abstract

Thermoresponsive nanomaterials have led to a plethora of new applications in the fields of Nanobiotechnology, Biomedicine and Therapeutics. Since liposomal membranes are lyotropic liquid crystals, the development of thermoresponsive liposomes for drug delivery has been recognized as an attractive scientific field. Additionally, plenty of studies utilizing the temperature-dependent response of certain synthetic polymers are conducted, alone or in combination with liposomes. In the present study, we combined the liposomal and thermoresponsive polymer technologies, in order to create functional chimeric/mixed liposomal nanosystems with innovative properties. Initially, differential scanning calorimetry was applied on chimeric/mixed bilayers to evaluate the effect of polymeric guests on the thermotropic behavior of lipidic membranes. Thereafter, chimeric/mixed liposomes were built and their physicochemical properties, as well as their colloidal stability were measured and evaluated. The nature of the self-assembled structures and the lipidic membrane morphology were investigated through cryo-transmission electron microscopy, while their thermoresponsiveness and its consequences on the lipidic membrane properties were assessed, through a simple heating protocol. The presence of a new thermodynamic phase on the lipidic membrane acts as an agglomeration and aggregation inducer, affecting the whole colloidal chimeric/mixed nanosystem. This mechanism might be characterized as “phase functionality” and may be utilized for drug delivery purposes and also in other applications. Biophysics and thermodynamics are very important tools to study the self-assembly process, as well as the stability and bio-functionality of drug delivery systems.