Additionally, the morphology of IND-NLC-SA nanoparticles functionalized with D-(+)-mannose at 1:2 SA: MAN ratio for 72 h (IND-NLC-SA-MAN) was evaluated through Transmission Electron Microscopy (TEM). Colloidal dispersions were placed onto cooper grids coated with a carbon membrane and stained with 2% (w/v) phosphotungstic acid solution for 2 min, following a previously described procedure [26] (link). The observation was conducted using a JEOL microscope (JEM 2010, Tokyo, Japan) equipped with a Gatan OriusTM camera (Gatan, Inc., Pleasanton, CA, USA).
Drug loading (DL) within the lipid network after purification (dialysis) of each formulation was calculated using Eq. 1, before and after storage. To determine actual drug content, samples were dissolved in acetonitrile and centrifuged at 12,000 rpm and 4 °C for 30 min. The supernatants were filtered through 0.45 μm and properly diluted in acetonitrile. IND quantification was performed spectrophotometrically at 322 nm.