In pursuit of key features for constructing electrochemical biosensors – electrochemical and acid-base characteristic of self-assembled monolayers on gold

ABSTRACT

Electrochemical biosensors are a well-known group of tools used widely in a variety of industries. Due to interactions between analytes and a surface, a measurable signal occurs which can then be processed to quantitative and/or qualitative data. The knowledge of surfaces’ electrochemical properties as well as their pK_a is of great importance when it comes to the construction of biosensors based on an electrochemical signal. In our work, we focused on determining electrochemical properties as well as pK_a of thiol-based SAMs – commonly used linker layers in biosensors. By applying cyclic voltammetry and electrochemical spectroscopy we were able to describe the overall resistive behaviour of SAMs synthesised with both alkanethiols and thiols with carboxyl and amine groups. Coherent use of contact angle measurements let us also describe the overall polarity of the investigated surfaces. The obtained data of pK_a values differed from the ones described for bulk solutions of modifying agents, which yields important information for further modification of the surface.

GRAPHICAL ABSTRACT

KEYWORDS:

• Surface pK_a
• self-assembled monolayer
• gold
• electrochemistry
• contact angle

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the University of Gdansk under [Grant No. 538-8210-B325-18].