ROS-Responsive Glycopolymeric Nanoparticles for Enhanced Drug Delivery to Macrophages

H2O2-Responsive Polymeric Micelles of Biodegradable Aliphatic Poly(carbonate)s as Promising Therapeutic Agents for Inflammatory Diseases

Excessive amounts of reactive oxygen species (ROS) cause various biological damages and are involved in many diseases, such as cancer, inflammatory and thrombotic complications, and neurodegenerative diseases. Thus, ROS-responsive polymers with inherent ROS scavenging activity and biodegradability are extremely needed for the efficient treatment of ROS-related diseases. Here, this work fabricates the amphiphilic diblock copolymer PEG-b-PBC via ring-opening polymerization (ROP) of phenylboronic acid ester conjugated cyclic carbonate monomer. The copolymer easily forms micelles (BCM) and scavenges ROS rapidly. BCM not only releases the delivered drug but degrades to produce the small molecules p-hydroxybenzyl alcohol (HBA) with anti-inflammatory capability in the presence of H2O2. BCM can reduce the oxidative stress of human umbilical vein endothelial cells (HUVEC) and the levels of inflammatory factors secreted by macrophages, showing antioxidative and anti-inflammatory activity. Finally, BCM exerts a significant capability to reduce the complications of inflammation and thrombosis in vivo. The biodegradable aliphatic poly(carbonate)s have the potential to be used for drug delivery systems (DDS) for diseases induced by reactive oxygen species.

ROS-responsive phenylboronic ester-based nanovesicles as multifunctional drug delivery systems for the treatment of inflammatory and thrombotic complications

Inflammatory and thrombotic complications and a low loading of dual drugs with different hydrophilicities remain challenges to treat thrombosis with drug delivery systems (DDSs). Here, the reactive oxygen species (ROS)-responsive amphiphilic block polymer poly(ethylene glycol)-b-2-((((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)carbonyl)oxy)-ethyl methacrylate (PEG-b-PTBEM) was synthesized and nanovesicles (PPTV) were prepared successfully for the drug delivery platform by controlling the hydrophilic/hydrophobic ratio of molecular chains and molecular self-assembly. The anti-inflammatory drug indomethacin (IDM) was loaded in the wall of nanovesicles and the thrombolytic enzyme nattokinase (NK) was encapsulated in the aqueous cavity of nanovesicles. Both drugs could be rapidly released at the site of thrombosis and/or inflammation with an excessive ROS concentration. The dual drug-loaded nanovesicles not only eliminated ROS, but also alleviated inflammation and dissolved the generated thrombus, showing significant therapeutic efficacy in the in vivo mouse model of carrageenan tail thrombosis. Therefore, drug-delivery nanovesicles play multiple roles in the treatment of inflammation-induced thrombotic disorders, which offer a promising treatment for inflammatory and thrombotic complications.

Dual-Responsive Glycopolymers for Intracellular Codelivery of Antigen and Lipophilic Adjuvants

Traditional approaches to vaccines use whole organisms to trigger an immune response, but they do not typically generate robust cellular-mediated immunity and have various safety risks. Subunit vaccines composed of proteins and/or peptides represent an attractive and safe alternative to whole organism vaccines, but they are poorly immunogenic. Though there are biological reasons for the poor immunogenicity of proteins and peptides, one other key to their relative lack of immunogenicity could be attributed to the poor pharmacokinetic properties of exogenously delivered proteins and peptides. For instance, peptides often aggregate at the site of injection and are not stable in biological fluids, proteins and peptides are rapidly cleared from circulation, and both have poor cellular internalization and endosomal escape. Herein, we developed a delivery system to address the lack of protein immunogenicity by overcoming delivery barriers as well as codelivering immune-stimulating adjuvants. The glycopolymeric nanoparticles (glycoNPs) are composed of a dual-stimuli-responsive block glycopolymer, poly[2-(diisopropylamino)ethyl methacrylate]-b-poly[(pyridyl disulfide ethyl methacrylate)-co-(methacrylamidoglucopyranose)] (p[DPA-b-(PDSMA-co-MAG)]). This polymer facilitates protein conjugation and cytosolic release, the pH-responsive release of lipophilic adjuvants, and pH-dependent membrane disruption to ensure cytosolic delivery of antigens. We synthesized p[DPA-b-(PDSMA-co-MAG)] by reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by the formation and physicochemical characterization of glycoNPs using the p[DPA-b-(PDSMA-co-MAG)] building blocks. These glycoNPs conjugated the model antigen ovalbumin (OVA) and released OVA in response to elevated glutathione levels. Moreover, the glycoNPs displayed pH-dependent drug release of the model hydrophobic drug Nile Red while also exhibiting pH-responsive endosomolytic behavior as indicated by a red blood cell hemolysis assay. GlycoNPs coloaded with OVA and the toll-like receptor 7/8 (TLR-7/8) agonist Resiquimod (R848) activated DC 2.4 dendritic cells (DCs) significantly more than free OVA and R848 and led to robust antigen presentation of the OVA epitope SIINFEKL on major histocompatibility complex I (MHC-I). In sum, the dual-stimuli-responsive glycopolymer introduced here overcomes major protein and peptide delivery barriers and could vastly improve the immunogenicity of protein-based vaccines.