Folic Acid-Conjugated Cellulose Nanocrystals ShowHigh Folate-Receptor Binding Affinity and Uptake by KB and BreastCancer Cells

摘要

The study evaluates cellulose nanocrystals (CNCs) as nanocarriers for targeted, intracellular delivery of molecular agents. CNCs were labeled with fluorescein-5′-isothiocyanate as an imaging agent and conjugated to folic acid (FA) as a targeting ligand. The CNC conjugates were characterized by UV–vis spectroscopy, ζ-potential analysis, dynamic light scattering, and atomic force microscopy. Cellular binding/uptake of the FA-conjugated CNCs by KB and MDA-MB-468 cells was quantified with cellular uptake assays. Internalization of the particles was confirmed by confocal microscopy. Uptake mechanisms were determined by inhibition studies with chlorpromazine and genistein. Binding affinity was qualitatively assessed with a free folate inhibition assay. Both KB and MDA-MB-468 cells exhibited significant and folate-receptor specific binding/uptake of FA-conjugated CNCs. Clathrin-mediated endocytosis was a significant uptake mechanism in both cell types, whereas caveolae-mediated endocytosis only played a significant role in MDA-MB-468 cells. Uptake inhibition of FA-conjugated CNCs by KB cells required high concentrations(>1 mM) of free FA. The observed FR-specific internalization ofFA-conjugatedCNCs by FR-positive cancer cells and tumors and their remarkable highaffinity for the FR demonstrate the great potential of CNCs as novelnanocarriers for imaging agents and chemotherapeutics in the earlydetection and treatment of cancer.