Silica nanochannel array on co-electrodeposited graphene-carbon nanotubes 3D composite film for antifouling detection of uric acid in human serum and urine samples

The present work reports a rapid and convenient electrochemical method for highly sensitive detection of uric acid (UA) by integration of vertically-ordered mesoporous silica film bearing amino groups (NH2-VMSF) and three-dimensional graphene-carbon nanotubes (3DG@CNT) composite film. 3DG@CNT and NH2-VMSF are successively modified onto the glassy carbon electrode (GCE) surface through a rather simple two-step controllable electrochemical deposition method. Arising from the large specific surface area, excellent electro-catalytic activity, and favorable mass transfer, 3DG@CNT co-electrodeposited onto the GCE surface could not only significantly improve the electrode performance, but also provide oxygen-containing groups for further functionalization. NH2-VMSF prepared by co-condensation approach using electrochemically assisted self-assembly method, possesses uniform pore size (-2 nm in diameter) and positively charged surface, showing pronounced anionic permselectivity. Thanks to the electroactive 3DG@CNT inner layer and electrostatically preconcentrated NH2-VMSF outer layer, the proposed NH2-VMSF/3DG@CNT/GCE displays outstanding analytical performance towards UA with a wide linear range (0.1 similar to 50 mu M), a high sensitivity (1.66 mu A.mu M-1) and a low limit of detection (6.8 nM). Furthermore, considering the inherent anti-fouling property of NH2-VMSF, direct analysis of UA in human serum and urine samples is achieved with satisfactory recoveries.