A physically small, antifouling sensor for selective detection of dopamine

In this work, we will focus on our efforts in developing structurally small carbon electrodes with considerable antifouling capabilities against both biofouling and electrochemical fouling, making them suitable for in vivo dopamine detection in a complex biological matrix. Very often, a challenge during in vivo dopamine detection is biofouling of electrodes arising from impeded electron transfer of
dopamine on an electrode by a nearly impermeable layer formed by nonspecifically adsorbed amphiphilic biological molecules (proteins, peptides, lipids, etc.) present in extracellular fluid. Similarly, oxidation of dopamine is known to yield an adsorbed dopamine-o-quinone layer on an electrode surface that leads to electrochemical fouling. Diminishing transient dopamine signals in such work have generated compromising results in time-dependent in vivo dopamine detection experiments. In this work, we have systematically investigated an organic silane reduction strategy on structurally small carbon electrodes (~2 μm tip diameters and ~9 μm axial length) to develop a hydrogenated carbon sensor with a hydrophobic surface that deters adsorption of amphiphilic species and dopamine-o-quinone, while favouring the dopamine electron transfer reaction. Results obtained using triethylsilane, n-butylsilane, phenylsilane, and diphenylsilane will be presented. The antifouling properties of these carbon electrodes will be compared by evaluating the analytical detection of dopamine at electrodes that were deliberately incubated in a laboratory synthetic fouling solution containing bovine serum albumin (a protein), cytochrome c (a protein), caproic acid (a lipid) and human fibrinopeptide (a peptide), before being applied to real-life biological samples.