A gold nanopopcorn attached single-walled carbon nanotube hybrid for rapid detection and killing of bacteria

Abstract

We report a strategy to fabricate a rapid and stable surface-enhanced Raman scattering (SERS)-based hybrid nanomaterial using gold nanopopcorns attached single-walled carbon nanotubes (AuNP@f₃-SWCNTs) for label-free detection and photothermal killing of bacteria. Herein, previously ester-functionalized single-walled carbon nanotubes (f₁-SWCNTs) undergo 1,3-dipolar cycloaddition reaction with in situ generated nitrile imine under Microwave (MW) irradiation to form a doubly ester terminated SWCNT cycloadduct (f₂-SWCNT). The ester terminals are further modified with 4-aminothiophenol (4-ATP) under MW-irradiation to form thiol-terminated SWCNT templates (f₃-SWCNTs) that allow gold nanopopcorns (AuNPs) to covalently and uniformly attach at a minimum inter-particle distance thus yielding a hybrid nanomaterial (AuNP@f₃-SWCNT) with good aqueous stability and abundant ‘hotspots’. Consequently, monoclonal E. coli antibody-conjugated bioassays fabricated with our AuNP@f₃-SWCNT substrates (mAb-AuNP@f₃-SWCNT) rapidly detect E. coli in water with good selectivity and impressive SERS sensitivity. The detection limit of E. coli 49979, selected as a model to establish proof of principle, was found to be 1.0 × 10² CFU mL⁻¹. Furthermore, the AuNP@f₃-SWCNT hybrid nanomaterial offers impressive photothermal pathogen killing effects. The synergy-type enhancement effect arising from the inherent noble properties of the respective components of the hybrid nanomaterial indicate that our AuNP@f₃-SWCNT has the potential for further application in multiplex detection in samples.