Development and evaluation of lipid nanocarriers for quercetin delivery: A comparative study of solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and lipid nanoemulsions (LNE)

To understand the effect of the physical state and composition of the lipid materials on the formation and performance of lipid nanocarriers, three types of carriers namely, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and lipid nanoemulsions (LNE) were prepared and compared. Quercetin was used as a model nutraceutical compound to evaluate the potency of these nanocarriers to increase bioaccessibility. Among the developed nanocarriers, quercetin loaded and free NLC showed the smallest particle size (∼34 and 47 nm) compared to SLN (∼103 and 127 nm) and LNE (∼82 and 83 nm). Encapsulation efficiency of quercetin in these nanocarriers was >90%. Stability of these nanocarriers in simulated stomach conditions was proved by their unaffected size and size distribution after incubation in simulated gastric fluid. Maximum bioaccessibility was observed with NLC and LNE (∼60%) compared to SLN (∼35%) and free quercetin solution (∼7%). Controlled release was observed in enzyme free simulated intestinal fluid with maximum release being obtained with LNE compared to SLN and NLC. This study showed that by optimally controlling the lipid physical state and composition, it is possible to fabricate the lipid nanocarriers with desired properties.