Silver nanoparticle-functionalized polydopamine nanotubes for highly sensitive nanocomposite electrode sensors

Multi wall carbon nanotubes (MWCNTs) are used in construction of nanocomposite electrode for many sensors. However, the chemical stability of MWCNTs also implicated difficulties for surface modification and further functionalization. Polydopamine nanotubes (PDA-NTs) possess nitrogen-doped polycyclic aromatic hydrocarbons sidewalls, which not only reassemble the structure and the electrochemical properties of carbon nanotubes, but also afford active surfaces for further functionalization. This work examines the fabrication of PDA-NTs with silver nanoparticles (AgNPs) for construction of nanocomposite electrodes for highly sensitive chemical analysis. The prepared PDA-NTs share the similar backbone structure like MWCNTs as analysis by Raman spectroscopy. Grown AgNPs significantly enhanced Raman peak intensity because of the surface enhancement of Raman scattering of AgNPs. In a test with hydrogen peroxide, Ag@PDA-NTs modified electrode showed an LDR of 5–200 μM and LOD of 0.68 μM, almost ten time lower than reported PDA and AgNPs modified electrode (LOD = 6.5 μM). It also owns good reproducibility, long-term stability and interfering effect against GLU, UA and DA. AgNPs can also grow more easily on PDA-NTs than on MWCNTs at the same AgNO₃ concentration and possess much better dispersivity at the same time. It appears that PDA supported nanofabrication is versatile and promising for development of high performance electrochemical sensors.