Fabrication, biomolecular assembly and electrochemical biosensing applications of highly ordered Ti–Pd alloy oxide nanotube arrays

Pd–TiO2 nanotube arrays (Pd–TNTs) which are highly ordered and vertically grown on Ti–0.2Pd alloy were fabricated by electrochemical anodization for the first time. The obtained Pd–TNTs were utilized as a “super vessel” for assembly of myoglobin (Mb) and biosensing applications. Experimental results demonstrate that the resulting Pd–TNTs display an enhanced capability for the immobilization of myoglobin. The direct electrochemistry of the immobilized Mb is dramatically facilitated, indicated by a couple of well-defined redox peaks and a very large electron transfer rate constant (ks) of 20.7 s− 1. Furthermore, Mb/Pd–TNTs present excellent electrocatalytic activity for the detection of trichloroacetic acid with a wide linear range from 0.5 to 96 μM and a low detection limit of 94 nM (3 N/S). Pd–TNTs with highly ordered nanotubular structure open a facile way to obtain ideal materials for biomolecular assembly and construct electrochemical biosensors.

The dramatically facilitated direct electron transfer of myoglobin (Mb) was obtained in the Ti–Pd alloy oxide nanotube arrays (Pd–TNTs) that are highly ordered and vertically grown on Ti–0.2Pd alloy, which can be ascribed to the reason that the conductivity of Pd–TNTs is much better than that of TNTs while nanotubular structure is almost same. The biosensor proves its high sensitivity to detect trichloroacetic acid in waters.Figure optionsDownload as PowerPoint slideHighlights
► Nanotube arrays (Pd–TNTs) vertically aligned on Ti–0.2Pd alloy are fabricated by electrochemical anodization.
► The conductivity of Pd–TNTs is much better than that of TNTs while nanotubular structure is almost same.
► Numerous “empty vessels” can lead to large surface myoglobin coverage of 1.6 × 10− 9 mol cm− 2.
► Facilitated direct electron transfer of myoglobin with electron transfer rate constant (ks) of 20.7 is achieved.
► Mb/Pd–TNTs exhibit excellent electrocatalytic activity for the sensitive detection of trichloroacetic acid.