On the influence of polyethyleneimine modification in nanogel-driven drug delivery

Nanogels are nanometric three-dimensional structures formed by chemically or physically cross-linked polymers with hydrophilic or amphiphilic macromolecular chains. Biocompatibility, biodegradability, water solubility and nontoxicity are the properties of these colloids that make them very interesting to be used in biomedical fields and especially in drug delivery applications. Several strategies have been proposed for the preparation of nanogels capable to uptake and release a great variety of drug compounds; however, the encapsulation of hy-drophobic compounds inside the structure of nanogels has been proven difficult. The goal of this work is to study how drug delivery performances can be influenced by the chemical modification of linear polyethyleneimine (PEI) structure and if the ability to load and release hydrophobic drugs from nanogels can be improved in this way. In vitro drug release tests were performed by using rhodamine B and pyrene as model hydrophilic and hydrophobic drug mimetics, respectively. The maintenance of an efficient drug release ability was confirmed for hydrophilic compounds (cumulative release up to 80 % in 120 h) like in our previous formulations, but an optimal loading and encapsulation efficiency, with a time-controlled release, emerged also for hydrophobic molecules, due to the introduction of the modifications in the nanogel framework.