Biodegradable Covalent beta-Cyclodextrin Nanocages for Acidic and
Reductive-Responsive Drug Delivery in Enhanced Tumor Therapy
Abstract
Traditional beta-cyclodextrin (beta-CD) in biomedical applications faces
challenges due to its inherent physical and biochemical limitations. One
of the most effective strategies to enhance the properties of beta-CD
for drug delivery is the synthesis of supramolecular polycyclodextrins.
In this study, we designed a novel beta-CD nanocage-like structure for
drug delivery, incorporating imine and disulfide bonds through Schiff
base reactions. Aldehyde group-functionalized beta-CD units were used to
construct the main backbone of the nanocage, forming dual-dynamic
covalent bonds. The chemical structure of the beta-CD nanocage was
confirmed using ¹H nuclear magnetic resonance (¹H NMR) and fourier
transform infrared spectroscopy (FTIR). Additionally, atomic force
microscopy (AFM) and dynamic light scattering (DLS) revealed that
varying amounts of beta-CD crosslinked with cystamine resulted in
nanocages approximately 200 nm in size. In vitro drug release
experiments demonstrated that doxorubicin (DOX)-loaded beta-CD nanocages
exhibited accelerated DOX release in acidic and reductive environments
compared to normal physiological conditions, owing to the pH-sensitive
imine bond and the glutathione (GSH)-cleavable disulfide bond. The
DOX-loaded beta-CD nanocages showed exceptional tumor-killing effects,
particularly in acid/reduction-enhanced tumor cells. Both cellular
fluorescence imaging and flow cytometry confirmed the potential of the
beta-CD nanocages for acid/reduction-specific drug release.
Consequently, this precision medicine model using imine/disulfide-linked
beta-CD nanocage structures as acidity/reduction-sensitive drug carriers
promises to improve oncotherapy through more targeted drug delivery and
release, supporting individualized treatment approaches.