Pluronic/gelatin composites for controlled release of actives

• Synthesis of a Pluronic F127-gelatin composite for applications in drug delivery.
• The gelatin presence increases the critical micellar temperature of Pluronic F127.
• Study of the release of azorubine at different pH and temperature conditions.
• Fitting with Weibull equation reveals a temperature-dependent release mechanism.
• Pluronic F127 hydrogel compensates for gelatin loss of rigidity at 37 °C.

This paper describes the preparation and the release properties of composite materials based on Pluronic F127 and gelatin hydrogels, which could be of interest in the field of enteral nutrition or drug administration. The composites were prepared by exploiting the opposite responsivity to temperature of a 20% w/w Pluronic F127 aqueous solution (critical gelation temperature around 23 °C) and gelatin (gel–sol temperature transition around 30 °C). Pluronic domains dispersed within a gelatin matrix were obtained by injecting cold Pluronic F127 solutions inside hot gelatin solutions, while homogenizing either with a magnetic stirrer or a high-energy mechanical disperser. Calorimetry indicates that the composites retain the individual gelling properties of Pluronic and gelatin. Different releasing properties were obtained as a function of the preparation protocol, the temperature and the pH. The release profiles have been studied by a Weibull analysis that clearly points out the dominating role of gelatin at 25 °C. At 37 °C the release accounts for a combined effect from both Pluronic F127 and gelatin, showing a more sustained profile with respect to gelatin hydrogels. This behavior, together with the ability of Pluronic F127 to upload both hydrophilic and hydrophobic drugs and flavors, makes these innovative composite materials very good candidates as FDA-approved carriers for enteral administration.

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