Microwave radiation-assisted covalent functionalization of boron nitride nanotubes and their grafting with cationic thermo and pH-sensitive hydrogel

Abstract

Sensitive hydrogels target the delivery of chemotherapeutic drugs to tumor tissues as these polymeric nets respond to environmental changes caused by growing cancerous tissues. A major concern with hydrogels is low mechanical resistance, what could be mitigated by combining these polymers to mechanically resistant inorganic materials like nanotubes. Boron nitride nanotubes (BNNT) exhibit biocompatibility and high mechanical resistance but are unable to control the release of molecules based on the conditions of a given suspension medium. Grafting sensitive hydrogels to BNNT presents a way to gather features of both phases, creating a potential drug delivery system (DDS) capable of withstanding the shear stress of the bloodstream. In this study BNNT were obtained via chemical vapor deposition (CVD) and oxidized by strong acids before being covalently functionalized by microwave radiation-assisted grafting. Thermo and pH-sensitive Poly[(N-iPAAm)-co-(DEAEMA)] hydrogels were synthesized using free radical polymerization both isolated, creating a purely polymeric sample, and in the presence of functionalized BNNT, creating the BNNT-TEGDMA/Poly[(N-iPAAm)-co-(DEAEMA)] hybrid sample. The hybrid sample represents the first time that, to the best of our concern, BNNT have been coated with in situ synthesized cationic hydrogel. The samples were characterized using XRD, SEM, TEM–EELS, FTIR, XPS, TGA, DSC, and elemental analysis. The results indicate that BNNT were successfully synthesized, oxidized, and covalently functionalized. These results also show that hydrogels were obtained in the absence and in the presence of functionalized nanotubes and could form the dual-phase hybrid material, which was shown to be sensitive to temperature and pH variations.