Nucleic acid-scavenging electrospun nanofibrous meshes for suppressing inflammatory responses

Fragmented nucleic acids are potent stimulators for inflammatory responses provoking pathological outcomes by activating adaptive immunity. In this study, highly cationic surfaces were prepared on electrospun nanofibrous meshes to scavenge nucleic acids to the surfaces. Poly(ε-caprolactone) [PCL]-poly(ethylenimine) [PEI] block copolymers were synthesized by coupling the carboxyl-terminated PCL to the primary amines of branched PEI. Polymeric solutions composed of PCL-PEI and PCL were electrospun to nanofibrous mats, and the surfaces were further methylated to prepare highly cationic surfaces on the mats. Raman spectroscopy revealed that the presence of increased methylated amines on the surfaces of the mats compared to unmodified mats. The methylated surfaces showed significant increases of wettability after methylation, suggesting highly charged surfaces caused by methylation of the primary amines. When the blend ratio of PCL-PEI was increased, the scavenged DNA was also increased, and the methylation further strengthened the scavenging ability of the mats. Fluorescently labeled oligodeoxynucleic acids were significantly adsorbed on the surface of the mats depending on the amounts of PCL-PEI and the degree of methylation. In the presence of the methylated nanofibrous mats, inflammatory responses induced by CpG oligonucleotides in murine macrophages were significantly reduced, which was confirmed by measuring inflammatory cytokine levels including TNF-α and IFN-γ.