Nanogels properties

Fig. 3 Schematic picture of pH-sensitive, virus-mimetic (VM) nanogel and its in vitro swel-ling/deswelling property by particle size results between pH 7.4 and 6.5 (adapted from Ref. [25] with permission)...

PNIPAM is perhaps the mostly studied thermosensitive polymers and as such the majority of nanogels studied are based on PNIPAM. Recently, there has been much interest in developing PNIPAM alternatives. " Polymers based on OEGMAs have come to the forefront as a new generation of thermosensitive polymers with improved biocompatibility, sharpness of responsiveness, antifouling properties below LCST, and bio-ineitness. ... 

Lee JI, Kim HS, Yoo HS, DNA nanogels composed of chitosan and pluronic with thermo-sensitive and photo-crosshnking properties. 7 J Pharm, 2009, 373, 93-9. 

Apart from polyplexes, various nanoscale assemblies of cationic polysaccharides are also proposed to promote the surface-mediated delivery of DNA to cells. These approaches are classified into one of two broad categories (i) methods based upon the physical adsorption of preformed polyplex on polymeric surfaces like PLGA or collagen films and these polyplex functionalized films promoted surface-mediated transfection of cells in vitro and in vivof (ii) methods for layer-by-layer adsorption of DNA and cationic polymers on surfaces to fabricate multilayered thin films. Recently, degradable carbohydrate-based nanogels were proposed for codelivery of pDNA and therapeutic proteins. These systems were designed to possess stimuli-sensitive characteristics where the temperature-sensitive property of nanogels allowed the facile encapsulation of biomaterials, while... 

Over the last decades, several academic and industrial research programs have been focused on the development and production of appropriate biocompatible formulations that provide enhanced therapeutic performance. Three different strategies can be discerned that are applied separately or in combination (i) addition of excipients to proteins, such as protease inhibitors, penetration or absorption enhancers like bile salts, fatty acids, cyclodextrins or surfactants " (ii) modification of the physicochemical properties of proteins, e.g. by attachment of lipophilic or hydrophilic moieties or (iii) incorporation of proteins into polymeric or liposomal delivery carriers. " A variety of polymeric vectors has been developed and exploited for this purpose, including biodegradable nanoparticles, nanogels, micelles, polymer bioconjugates and soluble nanocomposites. These polymeric carriers are more extensively described in the following sub-sections. 

Cationic polymer-based nanogels are nanosized swollen cationic hydrogel particles composed of chemically or physically crosslinked polymer net-works/ The highly hydrated properties and tightly crosslinked core makes these systems superior in colloidal stability. These properties make these nanogels suitable for encapsulation of therapeutic nucleic acids in the core for carrier systems for delivery, in comparison to macroscopic hydrogels or nanoparticles. ... 

---