A mechanism of adsorption of beta-nicotinamide adenine dinucleotide on graphene sheets: experiment and theory.
Chemistry (Weinheim an der Bergstrasse, Germany)
confidence
Key findings
Adsorption of NAD+ on graphene edges and defects due to interaction with oxygen-containing groups; theoretical and XPS study of electrochemical passivation.
View source on PubMed (PMID 19746361) ↗
- Sample size
- N/A
- Population
- N/A (in vitro material study)
- Dosing
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- Duration
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- Route
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- Blinding
- not_reported
- Controls
- none
- Drug class
- coenzyme
Full abstract
Beta-nicotinamide adenine dinucleotide (NAD(+)) and its reduced form (NADH) play major roles in the development of electrochemical enzyme biosensors and biofuel cells. Unfortunately, the oxidation of NADH at carbon electrodes suffers from passivation of the electrodes and a decrease in passing currents. Here, we investigate experimentally and theoretically the reasons for such passivation. High-resolution X-ray photoelectron spectroscopy (HR-XPS), voltammetry, and amperometry show that adsorption occurs on the edges and "edge-like" defects of graphene sheets. HR-XPS and ab initio molecular dynamics show that the adsorption of NAD(+) molecules on the edges of graphene happens due to interaction with oxygen-containing groups such as carboxylic groups, while graphene edges substituted only with hydrogen are prone to passivation.