2 research outputs found
Multifunctional and Dual-Responsive Polymersomes as Robust Nanocontainers: Design, Formation by Sequential Post-Conjugations, and pH-Controlled Drug Release
Robust, multiresponsive, and multifunctional
nanovesicles are in
high demand not only as carrier systems but also for applications
in microsystem devices and nanotechnology. Hence, multifunctional,
pH-responsive, and photo-cross-linked polymersomes decorated with
adamantane and azide groups are prepared by mixed self-assembly of
suitably end-modified block copolymers and are used for the subsequent
postconjugation of the polymersome surface by using covalent and noncovalent
approaches. For the covalent approach, nitroveratryloxycarbonyl-protected
amine (NVOC) molecules as light-responsive moieties are introduced
into the polymersomes through an azide–alkyne click reaction.
After photocleavage of NVOC units, functional dye molecules react
with the now freely accessible amine groups. The noncovalent approach
is performed subsequently to introduce further moieties, making use
of the strong adamantane-β-cyclodextrin host–guest interactions.
It is quantitatively proven that all reactive groups have sufficient
accessibility as well selective and orthogonal reactivity throughout
these stepwise processes to allow the successful establishment of
aimed pH- and light-responsive multifunctional polymersomes. Moreover,
this sequential methodology is also applied to obtain doxorubicin-loaded
multifunctional polymersomes for an efficient pH-controlled drug release.
Overall, tunable membrane permeability combined with the potential
for introducing multiple targeting groups by light-exposure or host–guest
interactions make these smart polymersomes promising nanocontainers
for many applications
Immobilized Multifunctional Polymersomes on Solid Surfaces: Infrared Light-Induced Selective Photochemical Reactions, pH Responsive Behavior, and Probing Mechanical Properties under Liquid Phase
Fixing polymersomes onto surfaces
is in high demand not only for the characterization with advanced
microscopy techniques but also for designing specific compartments
in microsystem devices in the scope of nanobiotechnology. For this
purpose, this study reports the immobilization of multifunctional,
responsive, and photo-cross-linked polymersomes on solid substrates
by utilizing strong adamantane−β-cyclodextrin host–guest
interactions. To reduce nonspecific binding and retain better spherical
shape, the level of attractive forces acting on the immobilized polymersomes
was tuned through polyÂ(ethylene glycol) passivation as well as decreased β-cyclodextrin
content on the corresponding substrates. One significant feature of
this system is the pH responsivity of the polymersomes which has been
demonstrated by swelling of the immobilized vesicles at acidic condition
through in situ AFM measurements. Also, light responsivity has been
provided by introducing nitroveratryloxycarbonyl (NVOC) protected
amine molecules as photocleavable groups to the polymersome surface
before immobilization. The subsequent low-energy femtosecond pulsed
laser irradiation resulted in the cleavage of NVOC groups on immobilized
polymersomes which in turn led to free amino groups as an additional
functionality. The freed amines were further conjugated with a fluorescent
dye having an activated ester that illustrates the concept of bio/chemo
recognition for a potential binding of biological compounds. In addition
to the responsive nature, the mechanical stability of the analyzed
polymersomes was supported by computing Young’s modulus and
bending modulus of the membrane through force curves obtained by atomic
force microscopy measurements. Overall, polymersomes with a robust
and pH-swellable membrane combined with effective light responsive
behavior are promising tools to design smart and stable compartments
on surfaces for the development of microsystem devices such as chemo/biosensors