Effect of hydroxypropyl [beta]-cyclodextrin on the self-assembling and thermogelation properties of Poloxamer 407

Abstract

This paper deals with the rheological and thermal characterisation of the self-assembling behaviour of different Poloxamer 407 systems (15–30%, w/v), both alone or after the addition of various amounts of hydroxypropyl β-cyclodextrin (5–20%, w/v). The knowledge of the interactions existing between the two kinds of molecules could allow the development of systems for parenteral administration containing also proteins or peptides drugs. A rheology (temperature sweep and frequency sweep test) study has been performed to characterise the thermogelation process while thermal analysis (nanoDSC) allowed the determination of both micellization and sol/gelation transition processes. These two techniques were also utilised to outline the variation in the critical micelle temperature (cmT) or in the sol/gel temperature (sgT,) of the systems containing also hydroxypropyl β-cyclodextrin (HP β-CD). Both the rheology and thermal analysis showed the presence of interesting interactions between the HP β-CD and the Poloxamer 407, which cause a shift of both cmT and sgT. The presence of HP β-CD modified also Poloxamer samples elastic characters and microrheological structure as demonstrated by the G′–G″ mechanical spectra. Rheological and thermal results outlined how these new systems could open the possibility to join the thermogelling behaviour offered by Poloxamer 407 with the well-known stabilization and protection ability of HP β-CD, which could make possible the formulation of systems for the parenteral delivery of peptides and proteins.