Injectableand Quadruple-Functional Hydrogel as anAlternative to Intravenous Delivery for Enhanced Tumor Targeting

Intravenous (IV) route is the most commonly used drug-delivery approach. However, the targeting efficiency to tumor through IV delivery is usually less than 10%. To address this limitation, we report a new systemic delivery method utilizing injectable and quadruple-functional hydrogels to improve targeting efficiency through passive, active, and magnetic targeting, and hydrogel-controlled sustained release. The hydrogels consist of a folate/polyethylenimine-conjugated poly(organophosphazene) polymer, which encapsulates small interfering RNA (siRNA) and Au–Fe3O4 nanoparticles to form a nanocapsule (NC) structure by a simple mixing. The hydrogels are localized as a long-term “drug-release depot” after a single subcutaneous injection and sol–gel phase transition. NCs released from the hydrogels enter the circulatory systems and then target the tumor through enhanced permeability and retention/folate/magnetism triple-targeting, over the course of circulation, itself prolonged by the controlled release. In viv...