PEG-Based Hyperbranched Polymer Theranostics: Optimizing Chemistries for Improved Bioconjugation

Polymeric materials are receiving increasing attention as gene delivery vectors in nanomedicine. Because of their potential to combine many different functionalities into a single molecule, hyperbranched polymers (HBPs) are ideal for biomedical applications and have been utilized in a variety of applications ranging from molecular imaging to vectors for gene and drug delivery. In this study, we synthesized a model functional HBP as a potential theranostic, which can act as an imaging agent for F-19 MRI while at the same time carrying specific therapeutic genes (such as small-interfering RNA) to a site of interest. In order to realize such a goal, an in-depth analysis of the molecular structure of the theranostic was performed to ensure that the diagnostic (F-19 MRI) and therapeutic (gene therapy) components were complementary and did not compromise respective individual function. Importantly, it was necessary to demonstrate that the various chemistries utilized during the synthesis of the theranostic FIBPs were compatible and did not lead to unwanted degradation and subsequent formation of side-products. Ultimately, we show that through careful analysis of the polymeric materials we can gain an understanding of the subtle factors that influence successful development of a theranostic device that incorporates multiple specific functionalities.