Nanogels are hydrogels within the nanometres range consisting of crosslinked porous polymer networks with the ability to retain high volumes of water or biological fluids whilst maintaining their structure. They have a wide range of flexibility in their design, allowing their characteristics such as size, charge, degree of porosity and degradability to be easily tuned by the choice of monomeric building blocks. Since nanogels can retain a high volume of water, they are extremely biocompatible. This excellent and unique property makes them an ideal nanoplatform for the delivery of biological drugs such as enzymes and proteins. Nanogels are prepared via polymerization of monomers or precursors by chemical crosslinking or via physical crosslinking of preformed polymers via amphiphilic or electrostatic interactions. Nanogels have superior properties as they offer: 1) encapsulation stability for biologically sensitive payloads, 2) they have low immunogenicity and toxicity, and can be designed to be fully biodegradable, 3) multiple biological payloads can be delivered in a single nanogel, facilitating combination therapies, 4) their synthesis can be aqueous based and easily scaled, and 5) they are soft nanoparticles that can easily squeeze through restricted sites under hemodynamic shear flow. In this manner, nanogels are the ideal delivery platform for biological drugs especially since biological therapeutics can be encapsulated into nanogels using mild conditions.

This special theme will focus on methodology related to nanogel synthesis and characterization. The aim of this Methods Collection is to present methods including, but not limited to nanogel synthesis. We aim to include submissions based on nanogel synthesis involving both pre-formed polymer self-assemblies and various in-situ polymerisations based on surfactants, templates and co-solvent techniques.