Figure 2. Cell viability assay.

pBCEC were cultured in collagen IV-coated 96-well plates under the same conditions as for drug transport study. The cells were incubated for 24 h at 37°C with 0.26 mg nanoparticles per cm² growth area (0.26 mg NP/cm²) or 0.52 mg nanoparticles per cm² growth area (0.52 mg NP/cm²) of the different ApoE-modified (NP-ApoE) as well as the PEGylated (NP-PEG) nanoparticulate formulations, which were loaded with 100 µM or 1000 µM of obidoxime, HI 6 dichloride monohydrate (HI 6-DCL) or HI 6 dimethanesulfonate (HI 6-DMS). Afterwards, the viability was determined after addition of WST-1 reagent and measurement of formazan formation, as described in the manufacturer instructions manual. Untreated cells set the 100% standard.