ABSTRACT
Rapid endosomal escape of drug carriers is crucial to enhancing the efficacy of their macromolecular payload, especially proteins that are susceptible to lysosomal degradation. In this paper, we report poly(amino oxalate) (PAOX) as a new protein delivery system that is capable of disrupting endosomes and mediating cytosolic drug delivery. A cationic fully-biodegradable PAOX was synthesized from a one-step reaction of oxalyl chloride, cyclohexanedimethanol and piperazinediethanol. The incorporation of tertiary amine groups in the backbone of PAOX enhanced its hydrolytic nature, which results in a fast drug release. The studies of confocal fluorescence imaging using calcein and LysoTracker Red revealed that PAOX particles disrupted endosomes via "proton sponge" effects and mediated the cytosolic delivery of membrane-impermeable calcein. A protein delivery efficiency of PAOX particles was evaluated using catalase as a model protein. Catalase-loaded PAOX microparticles significantly inhibited hydrogen peroxide generation in Phorbol-12-myristate-13-acetate (PMA)-stimulated macrophages, in a dose-dependent manner. Given the excellent biocompatibility and physicochemical properties, we anticipate that PAOX is a promising cytosolic protein delivery system and is useful for the treatment of acute inflammatory diseases.
Subject(s)
Catalase/administration & dosage , Cytosol/metabolism , Drug Carriers/metabolism , Endosomes/metabolism , Oxalates/metabolism , Piperazines/metabolism , Polyesters/metabolism , Animals , Biocompatible Materials/chemical synthesis , Biocompatible Materials/metabolism , Catalase/pharmacology , Cell Line , Drug Carriers/chemical synthesis , Hydrogen Peroxide/metabolism , Macrophages/cytology , Macrophages/drug effects , Macrophages/metabolism , Mice , Oxalates/chemical synthesis , Piperazines/chemical synthesis , Polyesters/chemical synthesisABSTRACT
Drug delivery using biodegradable polymeric microparticles is becoming an important means of delivering therapeutic agents. In this work, we describe polyoxalate microparticles as a biodegradable and biocompatible protein drug-delivery system. Polyoxalate was synthesized from a polycondensation reaction between oxalyl chloride and 1,4-cyclohexanedimethanol under basic conditions. Polyoxalate, in design, undergoes hydrolytic degradation to generate non-toxic low-molecular-weight compounds that can be easily excreted from a body. Polyoxalate was hydrophobic and had a half-life of 6.5 days at pH 7.4. This hydrophobic polyoxalate could be formulated into microparticles by a double emulsion method and encapsulate proteins with a loading efficiency of more than 80%. Cytotoxicity evaluation using RAW 264.7 cells indicated that polyoxalate microparticles exhibited a cytotoxicity profile superior to PLGA microparticles. The polyoxalate microparticles were taken up by macrophages in vitro as confirmed by confocal fluorescence microscopy. The ease of synthesis coupled with the physicochemical properties and excellent biocompatibility make this polyoxalate a promising candidate for protein-delivery applications.
Subject(s)
Biocompatible Materials/chemistry , Drug Delivery Systems/methods , Oxalates/chemistry , Animals , Cells, Cultured , Drug Carriers/chemistry , Hydrogen-Ion Concentration , Kinetics , Mice , Microscopy, Confocal , Microscopy, Electron, Scanning , Microspheres , Nanoparticles/chemistry , Particle Size , PhagocytosisABSTRACT
One of major challenges in the drug delivery lies in the development of nanoparticles that are effectively delivered to targeted cells and release their payload over an extended period to achieve a clinical response. In this paper, we report a new family of biocompatible and biodegradable polymer, termed polyoxalate that degrades hydrolytically into nontoxic byproducts. Polyoxalate was synthesized from a simple one-step polymerization reaction of 1,4-cyclohexanedimethanol and oxalyl chloride and had a MW of approximately 11000 Da. This polymer was designed to degrade by water hydrolysis into 1,4-cyclohexanedimethanol and oxalic acid, which can be easily removed from a body. Polyoxalate had a hydrophobic backbone and was formulated into nanoparticles with a mean diameter of 600 nm, which is suitable for drug delivery involving phagocytosis by macrophages. Polyoxalate nanoparticles were readily taken up by RAW 264.7 macrophage cells and HEK (human embryonic kidney) 293 cells and exhibited a minimal cytotoxicity in a time- and dose-dependent manner. In comparison with PLGA nanoparticles, polyoxalate nanoparticles had a significantly higher cell viability. We anticipated that the ease of synthesis and excellent biocompatibility make polyoxalate highly potent for numerous applications in drug delivery.