Conical nanofluidic channel for selective quantitation of melamine in combination with β-cyclodextrin and a single-walled carbon nanotube

Amine group-bearing small molecules tend to adsorb onto the nanochannel surfaces, which degrades the efficiency of nanochannel sensors. In this study, we utilized host-guest knowledge to eliminate the influence of excessive small molecules. In combination with single-walled carbon nanotubes (SWNTs), beta-cyclodextrin (beta-CD) provided an excellent sensing performance for the conical nanochannel coated with polyethyleneimine (PEI) and zirconium ion (Zr4+). By taking detection of melamine as a prototype, the as-prepared nanochannel could selectively detect melamine-elicited double-stranded DNA (dsDNA). Both excessive melamine and single-stranded DNA were removed via the addition of beta-CD and SWNTs. The nanochannel sensing platform for the detection of melamine has a detection limit of as low as 4.3 nM with a suitable sensitivity, an excellent reproducibility and stability. Therefore, it is highly promising that a nanochannel sensor based on ion current rectification (ICR) can be used to detect other possible targets.