Details

Autor(en) / Beteiligte

• Sharma, Abeera
• Bhattarai, Jay K.
• Nigudkar, Swati S.
• Pistorio, Salvatore G.
• Demchenko, Alexei V.
• Stine, Keith J.

Titel

Electrochemical impedance spectroscopy study of carbohydrate-terminated alkanethiol monolayers on nanoporous gold: Implications for pore wetting

Ist Teil von

• Journal of electroanalytical chemistry (Lausanne, Switzerland), 2016-12, Vol.782, p.174-181

Ort / Verlag

Switzerland: Elsevier B.V

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• Electrochemical impedance spectroscopy (EIS) is used to compare the apparent electron transfer rate constant (kapp) for a series of alkanethiol and of carbohydrate-terminated alkanethiol self-assembled monolayers (SAMs) on both flat gold and on nanoporous gold (np-Au). Using the surface area for np-Au determined by oxide stripping, the values of kapp for the alkanethiol modified np-Au are initially over two orders of magnitude smaller than the values found on flat Au. This result provides evidence that the diffusing redox probe Fe(CN)63−/4− only accesses a fraction of the np-Au surface after alkanethiol modification suggesting very limited wetting of the internal pores due to the hydrophobic nature of these surfaces. In contrast, for np-Au modified by carbohydrate-terminated (mannose or galactose) alkanethiols the values of kapp are about 10–40 fold smaller than on flat gold, suggesting more extensive access of the diffusing redox probe within the pores and better but still incomplete wetting, a result also found for modification of np-Au with mercaptododecanoic acid. A short chain PEG thiol derivative is found to result in a comparison of kapp values that suggests nearly complete wetting of the internal pores for this highly hydrophilic derivative. These results are of significance for the potential applications of SAM modified np-Au in electrochemical sensors, especially for those based on carbohydrate–protein recognition, or those of np-Au modified by SAMs with polar terminal groups. [Display omitted] •Impedance spectroscopy applied to self-assembled monolayers (SAMs) on gold and on nanoporous gold (np-Au)•Comparison of a series of alkanethiols as SAMs on both surfaces•Comparison of carbohydrate terminated alkanethiols as SAMs on both surfaces•Results for electron transfer rate constants suggest limited wetting of alkanethiol modified np-Au.•Results suggest partial wetting with carbohydrate derivatives and full wetting with an oxyethylene derivative.