Alginate Supramolecular Hydrogels Based on Viologen and
Cucurbit[8]uril: Host-Induced Caveolae-Mediated Endocytosis to White
Blood Cancer Cells
Abstract
The cellular uptake of drug carriers to the cytosol of a specific cell
remains challenging, and a non-classical supramolecular strategy is
motivated. Here, we select a model host-guest complex in which a
diamino-viologen (VG) fluorescent tag was engulfed by
cucurbit[8]uril (CB8) and covalently linked to alginate
polysaccharides (ALG) as the modified drug vehicle. When adsorbed on the
ALG surface, the encapsulation of VG was first confirmed utilizing FTIR
and NMR spectroscopic methods. Solid optical measurements (DRS, PL, and
TRPL) revealed emissive materials at around 650 nm and that CB8 enhanced
the rigidity of the modified hydrogel. The molar composition of 2 to 1
for the complexation of VG to CB8 on the alginate surface and the
thermal stabilities were also confirmed using TGA and DSC techniques.
CB8 induced a dramatic decrease in the average size of the VGALG
polysaccharides from 485 to 165 nm and a turnover in their charge from
-19.8 to +14.4 mV. Flow cytometry with inhibitors of various endocytosis
pathways was employed to track the cellular uptake across different
blood cell types: human T-cell leukemia 1301 and peripheral blood
mononuclear cells. Noticeably, complexation of VG to CB8 host on top of
the sugar platform dramatically enhanced the internalization to 1301
cells (viz. from 1 to 99%) at a concentration of 1.8 mg/mL via
caveolae-mediated endocytosis (CvME) because of the size reduction,
turnover in the charge from negative to positive, and rigidity
induction. These observations reveal a more profound understanding of
the macrocyclic effects on drug delivery