Functionalization of halloysite nanotube surfaces via controlled living radical polymerization: covalent immobilization of penicillin for a bioactive interface

Abstract

AbstractBackgroundSurface functionalization of nanomaterials has attracted much attention in the fields of chemistry, materials science, biology, and medicine because the surface chemistry and topology of nanomaterials has dramatic effects on the resulting material properties. Various strategies have been employed to modify the surface properties of substrates, including the immobilization of polymer brushes on a solid substrate using ‘living’/controlled radical polymerization methods.ResultsA halloysite nanotubes (HNTs) surface was fabricated through the growth of poly(ethylene glycol)‐based brushes (PPEGMA) via a living radical polymerization method followed by coupling of a model antibiotic, penicillin (PE). Fourier transform infrared (FTIR) spectroscopy confirmed all three segments of the nanohybrids were covalently attached. Successful covalent functionalization was also confirmed using X‐ray photoelectron spectroscopy (XPS) and energy dispersive X‐ray (EDX) spectrometry. The field emission scanning electron microscopy (FE‐SEM) images of the nanohybrids showed that a soft layer of polymer was immobilized on the nanotubes. Bioassay studies revealed that the covalently attached penicillin retained its antibacterial properties against E. coli and S. aureus.ConclusionA synthetic strategy for the functionalization of HNTs PPEGMA via surface‐initiated atom transfer radical polymerization (SI‐ATRP) has been successfully developed to permit covalent immobilization of antibiotics. First, PPEGMA‐grafted HNTs (HNTs‐g‐PPEGMA) were synthesized via a controlled SI‐ATRP of PPEGMA, followed by silanization using (3‐aminopropyl)trimethoxysilane to afford amine group‐containing nanohybrids (HNTs‐g‐PPEGMA‐NH2). Subsequently, PE was anchored to the surface of HNTs‐g‐PPEGMA‐NH2 via carbodiimide chemistry. The high bactericidal efficiency of the synthetic hybrid towards gram‐positive S. aureus and gram‐negative E. coli was demonstrated. Thus, this biofunctionalization strategy holds great potential for applications in the field of bio‐nanotechnology. © 2018 Society of Chemical Industry