Direct electrochemical detection of guanosine-5′-monophosphate at choline monolayer supported and gold nanocages functionalized carbon nanotubes sensing interface

A convenient and rapid system was developed for direct electrochemical detection of guanosine-5′-monophosphate (GMP) based on the construction of choline (Ch) monolayer supported and gold nanocages (Au NCs) functionalized carbon nanotubes sensing interface. Taking advantage of positively charged Ch film with -N+(CH3)3 polar head groups, Au NCs-carbon nanotubes nanocomposite could be uniformly and compactly assembled onto electrode surface, and Au NCs were favorable for the functionalization of sensing interface because of their hollow interiors and porous walls. The proposed system displayed prominent electrocatalytic activity towards the oxidation of GMP due to the well distribution status, large electroactive area, as well as fast electron transfer kinetics of sensing interface. As a result, GMP was sensitively detected with a low detection limit of 0.1 μM. Moreover, the sensing platform was applied in the assessment of GMP levels in oligonucleotides with satisfactory results. In contrast to the detection performances of other methods, the present work exhibited advantages of rapidity, low cost, and ease of operation, which may make the sensing system promising for potential applications in DNA assay and the fundamental research of interfacial electrochemistry.