Tunable nanogels by host-guest interaction with carboxylate pillar[5]arene for controlled encapsulation and release of doxorubicin

Nanogels have become one of the most attractive systems for application as delivery vectors or for theragnostic approaches in nanomedicine, which is mainly related to the ease of their synthesis by precipitation polymerization. However, only a few suitable monomers have been reported so far and stabilization of the nanogels requires the incorporation of rather defined amounts of in most cases charged co-monomers, such as acrylic acid, which limits the flexibility in their design. Here, we present an alternative approach using a pyridinium based monomer, which not only provides stability due to the positive charge, but also allows the attachment of functional carboxylate-pillar[5]arene by the formation of a host-guest complex. This approach is tested on pH-sensitive nanogels based on the monomer N-[(2,2-dimethyl-1,3-dioxolane)methyl]acrylamide (DMDOMA) featuring an acetal group, which is hydrolysed under acidic conditions. As carboxylates are known to catalyze this hydrolysis, we tested different amounts of carboxylate-pillar[5]arenes to tune the hydrolysis rate of the acetal group and found a direct correlation. Additional encapsulation studies with doxorubicin (DOX) revealed that surface potential and charge density represent additional key factors not only for the loading capacity, but also for the release profile of the nanogels. The option to tune such properties simply by the addition of a co-factor, in this case, the carboxylate-pillar[5]arenes provides a powerful tool to optimize characteristics of functional nanogels for drug delivery or other applications.

Straightforward Access to Glycosylated, Acid Sensitive Nanogels by Host-Guest Interactions with Sugar-Modified Pillar[5]arenes

The introduction of specific targeting units to polymer nanogels usually requires tedious chemical modifications, which limits flexibility in the design of combinatorial approaches. Here, we present a straightforward and versatile method to reversibly introduce various carbohydrate-based targeting units to a pH-sensitive nanogel via host-guest interactions. Glucose-, mannose-, or fructose-modified pillar[5]arenes can adaptably and conveniently be introduced to the surface of the nanogel. Binding studies between these nanogels and the lectin Concanavalin A revealed a high selectivity and strong interaction with only the mannose-modified nanogels. With the addition of other pillar[5]arenes, the interaction can be influenced proving a dynamic exchange of the targeting units. In comparison with common covalent modifications of polymer nanostructures, the presented combination of straightforward precipitation polymerization and supramolecular interactions promises convenient access to adaptable nanostructures for high-throughput screening of targeted delivery systems.

Drug–polymer conjugates with dynamic cloud point temperatures based on poly(2-oxazoline) copolymers

A shift in cloud point temperatures of poly(2-oxazoline)/ACE inhibitor polymer drug conjugates occurs on release of the drug.

Degradable polycaprolactone nanoparticles stabilized via supramolecular host–guest interactions with pH-responsive polymer-pillar[5]arene conjugates

Smart nano-carriers such as micelles, vesicles or nanoparticles constructed from amphiphilic polymers promise a new generation of drug delivery systems featuring localized and controlled release.

Development and disassembly of single and multiple acid-cleavable block copolymer nanoassemblies for drug delivery

Acid-degradable block copolymer-based nanoassemblies are promising intracellular candidates for tumor-targeting drug delivery as they exhibit the enhanced release of encapsulated drugs through their dissociation.

Smart pH-Sensitive Nanogels for Controlled Release in an Acidic Environment

The encapsulation of therapeutic compounds into nanosized delivery vectors has become an important strategy to improve efficiency and reduce side effects in drug delivery applications. Here, we report the synthesis of pH-sensitive nanogels, which are based on the monomer N-[(2,2-dimethyl-1,3-dioxolane)methyl]acrylamide (DMDOMA) bearing an acid cleavable acetal group. Degradation studies revealed that these nanogels hydrolyze under acidic conditions and degrade completely, depending on the cross-linker, but are stable in physiological environment. The best performing system was further studied regarding its release kinetics using the anticancer drug doxorubicin. In vitro studies revealed a good compatibility of the unloaded nanogel and the capability of the doxorubicin loaded nanogel to mediate cytotoxic effects in a concentration and time-dependent manner with an even higher efficiency than the free drug. Based on the investigated features, the presented nanogels represent a promising and conveniently prepared alternative to existing carrier systems for drug delivery.