Grafting of pH-sensitive poly (N,N-dimethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate) onto HNTS via surface-initiated atom transfer radical polymerization for controllable drug release

ABSTRACT

Copolymer brushes composed of N,N-dimethylaminoethyl methacrylate (DMAEMA) and 2-hydroxyethyl methacrylate (HEMA) were tethered on the surface of HNTs (HNTs) through surface-initiated atom transfer radical polymerization (SI-ATRP). ATRP initiator was anchored to surface and copolymers were synthesized from surface with different compositions of monomers. Successful grafting of copolymer brushes was approved by FTIR, TGA, XPS, FE-SEM, TEM, and N₂ adsorption-desorption.¹H NMR was used to determine the composition of copolymers. pH-sensitive properties of copolymer-grafted nanotubes were investigated by UV-visible absorbance in different pH values. Finally, loading and in vitro drug release from neat and copolymer-grafted HNTs were investigated using diphenhydramine hydrochloride as a model drug. Incorporation of DMAEMA to structure of polymers led to pH sensitivity of grafted-copolymers and controlled release of drug upon varying the pH of release medium. pH-dependent drug release showed that drug release was increased by decreasing pH of release medium and increasing DMAEMA content.

GRAPHICAL ABSTRACT

KEYWORDS:

• Halloysite nanotubes
• N,N-dimethylaminoethyl methacrylate
• 2-hydroxyethyl methacrylate
• atom transfer radical polymerization
• ATRP
• drug release