Supramolecular Bioconjugates for Protein and Small Drug Delivery.

Supramolecular conjugation techniques have been developed to produce novel nanosized systems by assembling materials with diverse physicochemical and biological features. These techniques have been adapted to obtain innovative bioconjugates to deliver drugs with poor biopharmaceutical properties and nano-devices with potential “theranostic” activity. Supramolecular drug delivery systems include polymer therapeutics such as drug–polymer bioconjugates, and colloidal carriers such as micelles, liposomes, polyplexes, and organic and inorganic nanoparticles. By virtue of their wide array of chemical composition and properties, polymers represent key elements for the construction of novel supramoelcular formulations. Polymer bioconjugation is a fledged technique for fabrication of protein–polymer conjugates. PEGylation, in particular, produces derivatives with enhanced pharmacokinetic, immunological, and stability properties as compared to the parent protein. Over the years, new methods have been set up to obtain site-directed polymer conjugation. In this review we report few grafting to and growing from PEGylation examples for the preparation of therapeutically effective protein bioconjugates. Supramolecular formulations with unique properties can be also obtained by assembling functional polymers, targeting agents, physicochemical modifiers, and biomodulators. These systems may be designed for disease tissue disposition and cell recognition/penetration. Cyclodextrins, for example, have been functionalized with polyethylene glycol and folic acid to produce tumor-targeted drug carriers. Interesting results have been obtained with this novel class of drug delivery systems. In addition, responsive polymers have been conjugated to gold nanoparticles to endow a new colloidal platform with triggerable cell disposition properties, which can be exploited either in biomedicine or diagnosis.