A paper based graphene-nanocauliflower hybrid composite for point of care biosensing

Abstract

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 sonoelectrodeposition, producing a conductive paper with an extremely high electroactive surface area (0.29±0.13cm(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±0.02μM) and E. coli O157:H7 (≈4 CFUmL(-1)) were competitive with, or superior to, previously reported devices in the biosensing literature. The response time (6s for glucose and 12min 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.

Enhanced electrochemical biosensor and supercapacitor with 3D porous architectured graphene via salt impregnated inkjet maskless lithography

“…Graphene has emerged as one of the most attractive electrocatalytic transduction materials due to its extraordinary electrical and thermal conductivity, high mechanical strength, biocompatibility, high carrier capacity/mobility, and potential high surface area. [1][2][3] Specifically, electrodes comprising graphene and graphene derivatives (graphene nanoparticles, reduced graphene oxides, oxidized graphene, functionalized graphene) have demonstrated high electrical conductivity and/or catalytic capability. For example, in the past decade graphene has been used for electrode materials in electrochemical devices such as supercapacitors, 4 batteries, 5 fuel cells, 6 cell electrode stimuli 7,8 and sensors.…”

“…12 Numerous methods have been used to increase the electrochemical surface area (ECSA) of graphene. For example, nanosphere lithography using selfassembly of polystyrene, 13 silica, 14 or MnO 2 15 nanospheres has been shown to etch nanopores into CVD grown graphene to increase the defect density in the lattice structure (more edge planes) and consequently improved the sensitivity of electrochemical sensors. Others have constructed three-dimensional CVD grown graphene foam out of a nickel scaffold, 16 polystyrene colloidal particles as a sacrificial template, 17 as well as various other manufacturing methods derived from chemical vapor deposition, hydrothermal methods, and sugar-blowing production.…”

Cell-SELEX Based Identification of an RNA Aptamer for Escherichia coli and Its Use in Various Detection Formats

“…Although our assay sensitivity is lesser in comparison to some of the impedance based detection of E. coli reported earlier, these studies have more advanced impedimetric set-up, that either uses electrode with better surface area (Akbari et al, 2015; Burrs et al, 2016), or have probes chemically conjugated to the electrode’s surface (Guo et al, 2012). In other cases, the change in impedance is measured in terms of growth of bacteria on the electrode, rather than the antibody/antigen binding (Settu et al, 2015).…”

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

“…Anticancer drugs (doxorubicin) [72,95,96] Anticancer and other drugs [16] Anticancer drugs (doxorubicin) [97] Carbon quantum dots: Anticancer drugs (temozolomide) [28] (Bio)sensors Electrochemical: cholesterol [98]; glucose and bacteria [110]; avian leucosis virus [111]; organic liquids [112] Electrochemical: ATP metabolites [102]; oxygen [84] Electrochemical: Biotin [66] Carbon black: Electrochemical aptasensor for S. aureus [32]; electrochemical sensor for H 2 O 2 [33] Piezoelectric: strain, human motion [63,99,113] Piezoresistance and thermoelectric-based: pressure and temperature [103]; pressure [17]; strain, human motion [90,91,114];…”

“…These sensors can be divided into electrochemical, piezoelectric, optical and acoustic wave-based sensors. Electrochemical sensors were constructed for detecting cholesterol [98], glucose and pathogenic bacteria [110], avian leucosis virus [111] and organic liquids [112]. The biosensor for detecting cholesterol was based on chemically-modified nanocellulose, grafted with silylated GO and enriched with ZnO nanoparticles in order to enhance its electrical conductivity [98].…”