Physicochemical, morphological and thermal evaluation of lyotropic lipidic liquid crystalline nanoparticles: The effect of stimuli-responsive polymeric stabilizer

Non-lamellar liquid crystalline nanoparticles are promising drug delivery lipidic nanosystems, stabilized by amphiphilic block copolymers. In the present investigation, the widely used Poloxamer P407 is compared with the innovative stimuli-responsive polycationic block copolymer poly(2-(dimethylamino)ethyl methacrylate)-b-poly(lauryl methacrylate) (PDMAEMA-b-PLMA) as stabilizer for glyceryl monooleate (GMO) or phytantriol (PHYT)-based colloidal dispersions of liquid crystalline nanoparticles. As such, a variety of techniques was combined in order to comprehensively characterize these nanosystems in terms of physicochemical, morphological and thermal properties. Particle size, size distribution, ζ-potential and the fractal dimension parameter (df), calculated from light scattering data, as well as the morphology (from cryo-TEM analysis) of nanoparticles were markedly affected by the different lipid and type of polymeric stabilizer, indicating different kind of interfacial lipid-polymer interactions. Notably, PDMAEMA-b-PLMA block copolymer was effective as well as P407 in stabilizing the GMO-based, but not PHYT-based nanosystems. Furthermore, microcalorimetry, high-resolution ultrasound spectroscopy and rheology were applied to characterize the thermal behavior of these nanosystems, highlighting their transition temperatures. In conclusion, a detailed evaluation was carried out on liquid crystalline nanoparticles, providing significant information, useful for the development of innovative non-lamellar therapeutic nanosystems with advanced properties that can be successfully applied in the pharmaceutical nanotechnology field.