title: In-Depth Electrochemical Investigation of Surface Attachment Chemistry via Carbodiimide Coupling.
abstract: Aminoferrocene is used as an electroactive indicator to investigate carbodiimide coupling reactions on a carboxylic acid-functionalized self-assembled monolayer. The commonly used attachment chemistry with 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) is used for surface activation. A number of conditions are investigated, including EDC and NHS concentration, buffer solutions, incubation timing, and aminoferrocene concentration. Ferrocene is a well-documented electroactive species, and the number of surface-bound ferrocene species can be calculated using electrochemical methods. This capability allows determination of optimal conditions, as well as providing a method for comparing and investigating novel carboxylated surfaces. An EDC-mediated procedure with ∼5 mM EDC and NHS (1:1) made in water, with a full acid monolayer, with 250 μM aminoferrocene for 40 min was found to give the highest ferrocene attachment. An application of this is demonstrated for preparing a probe-DNA-coated surface for DNA sensing. By backfilling with aminoferrocene, a differential quantification of the amount of probe DNA available for sensing can be obtained. This provides an elegant method to monitor an important aspect, namely, probe surface characterization, which will be highly useful for biosensing purposes.
authors.affiliation: †Digital Sensing Limited, 16 Beatrice Tinsley Crescent, Albany, Auckland 0632, New Zealand.
authors.forename: Marsilea Adela
authors.initials: MA
authors.lastname: Booth
authors.affiliation: †Digital Sensing Limited, 16 Beatrice Tinsley Crescent, Albany, Auckland 0632, New Zealand.
authors.forename: Karthik
authors.initials: K
authors.lastname: Kannappan
authors.affiliation: †Digital Sensing Limited, 16 Beatrice Tinsley Crescent, Albany, Auckland 0632, New Zealand.|‡Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Ali
authors.initials: A
authors.lastname: Hosseini
authors.affiliation: †Digital Sensing Limited, 16 Beatrice Tinsley Crescent, Albany, Auckland 0632, New Zealand.|‡Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Ashton
authors.initials: A
authors.lastname: Partridge
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002234:Carbodiimides / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D013499:Surface Properties
chemical_list: D002234:Carbodiimides; D004247:DNA