Cellular uptake of nanoparticles with different drug loading efficiency in 2D and 3D cancer cellular models

Abstract

Cellular uptake of nanoparticles plays a crucial role in their biomedical applications. Despite abundant studies trying to understand the interaction between nanoparticles and cells, the influence of cell geometry and the drug loading efficiency on the uptake of nanoparticles remains unclear. In this study, poly(vinyl alcohol) (PVA) is micropatterned on polystyrene cell culture plates using UV photolithography to control the spreading area and shape of cancerous and normal cell lines. The effects of these factors on the cellular uptake of HPMA-based micelles were investigated. Cancer cells with larger sizes and circular shapes, had higher total micelle uptake, On the other hand, normal cells showed opposite behaviours. Moreover, the effect on drug loading efficiency on the cellular uptake of polymeric micelles together with cellulose nanoparticles was also investigated. Both nanoparticles used as nanocarrier of the potent anticancer agent, ellipticine (EPT) at varying amounts. In the self- assembled P(HPMA-co-MAA)-b-PMMA micelles, the drug loading efficiency of EPT was observed to range between 50.0% to 62.6% depending on the ratio between drug and polymer. The IC50 value of U87MG cells were 0.67, 0.64 and 0.92 μg/mL. for EPT-200, EPT-100 and EPT-50 respectively, showing a higher toxicity in micelles with higher drug loading content. However, the cytotoxicity values measured from U87MG spheroids were lower than those measured in the 2D model. Cellular uptake was studied by confocal microscopy and flow cytometry, showing that the higher EPT loaded micelles were taken up more efficiently by the cells. Additionally, self-fluorescent cellulose nanofibers (PHEA-g-CNFs) were also used to investigate the effect of loading efficiency on the cellular uptake. Additional negatively charged carboxylic groups of CNFs allowed for protonated EPT loading by electrostatic interactions at various drug loading capacities from 1.68 to 8.07 wt %. In vitro cytotoxicity of blank and EPT-nanocellulose was also investigated on 2D and 3D cellular models. Lower drug loading was favorable for cellular uptake of cancer and healthy cells. The results indicate that the geometry of cells and the drug loading efficiency influence the nanoparticle uptake and may shed light on the design of functional nanoparticles for anticancer drug delivery.