Limonene-loaded nanostructured lipid carriers incorporated in hydrogels: Enhanced acid stability and controlled release properties

Improving the acid stability of nanostructured lipid carriers (NLCs) is critical for broadening their engineering applications. The integration of NLCs with hydrogels results in a more stable, multifunctional system that facilitates the effective and sustained release of bioactive ingredients. In this study, The chitosan/alginate hydrogel (CAH) exhibited minimal limonene release under combined high-temperature and acidic conditions when the degree of carboxyl substitution (DS) of chitosan reached 17.68 ± 0.14 % (NLC-CAH1). It exhibited the lowest release rate and superior stability under high-temperature and acidic conditions. The cumulative release rates of limonene in NLC and NLC-CAH1 within 3 h of acid solution were 35.24 ± 0.97 % and 22.41 ± 2.09 %, respectively. The hydrogels effectively delayed the release of NLCs, reducing the release rate of limonene and facilitating a prolonged release of bioactive ingredients. Consequently, the NLCs-hydrogel system represents a novel delivery mechanism, and offers innovative strategies for the administration of lipophilic bioactive compounds.