Redox-Sensitive Nanoscale Coordination Polymers for Drug Delivery and Cancer Theranostics

Nanoscale coordination polymers (NCPs), with inherent biodegradability, chemical diversities, and porous structures, are a promising class of nanomaterials in the nanomedicine field. Herein, a unique type of redox-sensitive NCPs is constructed with manganese ions (Mn²⁺) and dithiodiglycolic acid as the disulfide (SS)-containing organic bridging ligand. The obtained Mn-SS NCPs with a mesoporous structure could be efficiently loaded with doxorubicin (DOX), a chemotherapeutics. The yielded Mn-SS/DOX nanoparticles are coated with a layer of polydopamine (PDA) and then modified by poly(ethylene glycol) (PEG). In such a Mn-SS/DOX@PDA-PEG NCP structure, the disulfide linkage (SS) within dithiodiglycolic acid can be cleaved in the presence of glutathione (GSH), leading to efficient redox-responsive dissociation of NCPs and the subsequent drug release. Meanwhile, Mn²⁺ in Mn-SS/DOX@PDA-PEG NCPs would offer a strong T1 contrast in magnetic resonance (MR) imaging, Upon intravenous injection, these Mn-SS/DOX@PDA-PEG NCPs show efficient tumor homing, as revealed by MR imaging, and offer an obviously improved in vivo therapeutic outcome compared to that achieved with free DOX.