A comparative study of carbon–platinum hybrid nanostructure architecture for amperometric biosensing

Abstract

Carbon and noble metal nanomaterials exhibit unique properties that have been explored over the last few decades for developing electrochemical sensors and biosensors. Hybridization of nanometals to carbon nanomaterials such as graphene or carbon nanotubes produces a synergistic effect on the electrocatalytic activity when compared to either material alone. However, to date there are no comparative studies that directly investigate the effects of nanocarbon concentration and nanocomposite arrangement on electron transport. This comparative study investigated the efficacy of various platinum-carbon hybrid nanostructures for amperometric biosensing. Electroactive surface area, sensitivity towards hydrogen peroxide, response time, limit of detection, and surface roughness were measured for various hybrid nanomaterial arrangements. Both design factors (nanocarbon concentration and network arrangement) influenced the performance of the reduced graphene oxide-based platforms; whereas only nanomaterial arrangement affected the performance of the carbon nanotube-composites. The highest sensitivity towards hydrogen peroxide for reduced graphene oxide nanocomposites (45 ± 3.2 μA mM(-1)) was measured for a graphene concentration of 2 mg mL(-1) in a "sandwich" structure; nanoplatinum layers enveloping the reduced graphene oxide. Likewise, the best carbon nanotube performance toward H2O2 (49 ± 1.4 μA mM(-1)) was measured for a sandwich-type structure with nanoplatinum. The enhanced electrocatalytic activity of this "sandwich" structure was due to a combined effect of electrical junctions formed amongst nanocarbon, and nanocomposite soldering to the electrode surface. The top-down carbon-platinum hybrid nanocomposites in this paper represent a simple, low-cost, approach for formation of high fidelity amperometric sensors with remarkable performance characteristics that are similar to bottom-up fabrication approaches.

A self-referencing biosensor for real-time monitoring of physiological ATP transport in plant systems

“…Previous work by Vanegas et al (2014) demonstrated the capability of this hybrid nanomaterial to enhance the electrochemical performance of amperometric sensors by vastly increasing the contact interface, as well as potentiating the electrical behaviour of the transducing component. The relatively high electroactive area of the rGO/nPt platform also permits larger enzymatic loading onto the sensor surface (compared to other nanomaterial platforms such as carbon nanotubes; see Vanegas et al (2014) for detailed discussion). Distribution of the enzymes within the hydrogel/sol-gel matrix was characterized by LSCM to emphasize the presence and distribution of each type of enzyme (right panel of Fig.…”

“…Based on a methodology similar to the one described by Vanegas et al (2014), a nanocomposite of reduced graphene oxide and nanoplatinum (rGO/nPt) was deposited on the tip of a Pt/Ir microelectrode (PI20033.0A10 MicroProbes©, 1-2 mm tip diameter, Gaithersburg, MD). Briefly, a GO solution was prepared in DI water at a concentration of 2 mg/mL, followed by ultrasonication for 30 min.…”

“…To image carbon and platinum nanomaterials, scanning electron microscopy (SEM) micrographs were taken using a JEOL 5600 LV, with accelerating voltage of 20-30 kV as described in Vanegas et al (2014). In order to corroborate the presence and distribution of GK and G3PO in the hydrogel/sol-gel matrix, laser scanning confocal microscopy (LSCM) images were taken using an Olympus FV1000 (Shinjuku, Japan) 6 laser multiscanning confocal system mounted on an Olympus IX81 inverted microscope.…”

“…DC potential amperometry (DCPA) was conducted in a working solutions of either TRIZMA buffer or MS media with 1 mM glycerol based on methods described in Vanegas et al (2014). The biosensor was polarized at constant potential of þ 700 mV versus Ag/ AgCl reference electrode with a sampling rate of 1 kHz; the electrical output signal was recorded while successively injecting ATP into the working solution.…”

Xanthine oxidase biosensor for monitoring meat spoilage

“…Based on the methodology described in previous work by our group 12,13 , amorphous platinum nanoclusters (nPt) were formed on the surface of the electrode via simultaneous sonication/electroplating at 10 V for 30 seconds in a solution of 1.44% chloroplatinic acid and 0.002% lead acetate. A CeO/rGO suspension was prepared by mixing CeO, GO, and AA in a 1 ml:2 mg:8 mg ratio, followed by ultrasonication for 30 minutes.…”