Figure 4. Characterisation of PLGA-Letrozole-NPs and anti-GD2-ch14.18/CHO-PLGA-NP mediated delivery of Letrozole exclusively to GBM cells in co-culture.

Nanoparticles were prepared from a PLGA polymer using a modified single emulsion evaporation method [32]. Size and zeta potential of each nanoparticle batch was measured in a Malvern Zetasizer. As evaluated through a content release study, 50% content release of PLGA-Let-NPs occurs 72 hours post-incubation in phosphate buffered saline (PBS) at 37°C (A). This was also the case in cell culture media (data not shown). SEM imaging displays PLGA-NPs at 50Kx maginification (B). In addition, SEM imaging (C) display the morphological changes which occur 15 minutes post-NP treatment with NPs evident on the cell surface (denoted by red arrows), 3 hours post-NP treatment and 36 hours later. (D) HT29 colorectal cancer cells were pre-incubated with Cell tracker Blue reagent while MZ-256 GBM cells were incubated with MitoGreen tracker prior to co-culture on glass bottom dishes. As shown, NP positive cells are represented as Cyan in the merged image of Blue Cell-tracker-HT29, Green Mitogreen-MZ-256 and Red-NP. Notably, NP encapsulation is noted exclusively in those cells who are also MitoGreen positive, that is, MZ-256 cells and not in HT29 (Blue) cells (Scale 50 μm).