Selectivein situpotential-assisted SAM formation on multi electrode arrays

Abstract

The selective modification of individual components in a biosensor array is challenging. To address this challenge, we present a generalizable approach to selectively modify and characterize individual gold surfaces in an array, in an in situ manner. This is achieved by taking advantage of the potential dependent adsorption/desorption of surface-modified organic molecules. Control of the applied potential of the individual sensors in an array where each acts as a working electrode provides differential derivatization of the sensor surfaces. To demonstrate this concept, two different self-assembled monolayer (SAM)-forming electrochemically addressable ω-ferrocenyl alkanethiols (C) are chemisorbed onto independent but spatially adjacent gold electrodes. The ferrocene alkanethiol does not chemisorb onto the surface when the applied potential is cathodic relative to the adsorption potential and the electrode remains underivatized. However, applying potentials that are modestly positive relative to the adsorption potential leads to extensive coverage within 10 min. The resulting SAM remains in a stable state while held at potentials <200 mV above the adsorption potential. In this state, the chemisorbed SAM does not significantly desorb nor do new ferrocenylalkythiols adsorb. Using three set applied potentials provides for controlled submonolayer alkylthiol marker coverage of each independent gold electrode. These three applied potentials are dependent upon the specifics of the respective adsorbate. Characterization of the ferrocene-modified electrodes via cyclic voltammetry demonstrates that each specific ferrocene marker is exclusively adsorbed to the desired target electrode.

Grafting of short elastin-like peptides using an electric field

“…2 a). Previous studies indicate that an applied positive potential vs. a Ag/AgCl reference electrode impacts the packing density of alkane thiols during adsorption, presumably via enhancing the electron transfer process between sulfur and gold surface 33 – 35 , and thus may also impact the packing density of the peptides in this study. Other studies have observed increases in packing density of a thioctic acid derivative when negative potentials were applied and suggested a potential-dependent surface reaction with no electron transfer was occurring 36 .…”

Modulating the Faradic Operation of All-Printed Organic Electrochemical Transistors by Facile in Situ Modification of the Gate Electrode

“…For long-chain alkanethiols on Au, significant shortening of processing time can be achieved by a potential-controlled assembly, , but a more time-effective strategy, which can be applied ideally to any SAM-forming thiol and even to biomacromolecules, is the potential-pulse-assisted method developed by Schuhmann and co-workers . This strategy, based on pulse-type potential modulation, yields SAM formation on polycrystalline gold within a few minutes and depends on the relationship between timestep and the length of the alkyl chain and on the point of zero charge of the electrode before and after SAM formation, which determines the potential range of the steps.…”

Controlling DNA/Surface Interactions for Potential Pulse‐Assisted Preparation of Multi‐Probe DNA Microarrays

“…[14][15][16][17][18] Haag et al presented a general approach to selectively modify individual gold electrodes in an array with alkylthiols, by using two gold wafers placed adjacent to each other. [19] Adsorption/desorption was controlled by applying constant potentials, while a cross-talk between electrodes was atenuated by keeping the already modified electrode at a so-called hold potential that neither desorbs immobilized aklylthiol layer nor promotes adsorption of a new layer.…”