▎ 摘　　要

We demonstrate the first report of graphene paper functionalized with fractal platinum nanocauliflower for use in electrochemical biosensing of small molecules (glucose) or detection of pathogenic bacteria (Escherichia coli O157:H7). Raman spectroscopy, scanning electron microscopy and energy dispersive spectroscopy show that graphene oxide-coated nanocellulose was partially reduced by both thermal treatment, and further reduced by chemical treatment (ascorbic acid). Fractal nanoplatinum with cauliflower-like morphology was formed on the reduced graphene oxide paper using pulsed sonoelec-trodeposition, producing a conductive paper with an extremely high electroactive surface area (0.29 +/- 0.13 cm(2)), confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. The platinum surface was functionalized with either glucose oxidase (via chitosan encapsulation) or a RNA aptamer (via covalent linking) for demonstration as a point of care biosensor. The detection limit for both glucose (0.08 +/- 0.02 mu M) and E. coli O157:H7 (approximate to 4 CFU mL(-1)) were competitive with, or superior to, previously reported devices in the biosensing literature. The response time (6 s for glucose and 12 min for E. coli) were also similar to silicon biochip and commercial electrode sensors. The results demonstrate that the nanocellulose-graphene-nanoplatinum material is an excellent paper-based platform for development of electrochemical biosensors targeting small molecules or whole cells for use in point of care biosensing. (C) 2016 Elsevier B.V. All rights reserved.