Stripping voltammetric detection of insulin at liquid–liquid microinterfaces in the presence of bovine albumin

Abstract

Electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) provides a platform for label-free detection of biomolecules. In this study, adsorptive stripping voltammetry (AdSV) was implemented at an array of microscale ITIES for the detection of the antidiabetic hormone insulin. By exploiting the potential-controlled adsorption of insulin at the ITIES, insulin was detected at 10 nM via subsequent voltammetric desorption. This is the lowest detected concentration reported to-date for a protein by electrochemistry at the ITIES. Surface coverage calculations indicate that between 0.1 and 1 monolayer of insulin forms at the interface over the 10-1000 nM concentration range of the hormone. In a step toward assessment of selectivity, the optimum adsorption potentials for insulin and albumin were determined to be 0.900 V and 0.975 V, respectively. When present in an aqueous mixture with albumin, insulin was detected by tuning the adsorption potential to 0.9 V, albeit with reduced sensitivity. This provides the first example of selective detection of one protein in the presence of another by exploiting optimal adsorption potentials. The results presented here provide a route to the improvement of detection limits and achievement of selectivity for protein detection by electrochemistry at the ITIES.

Electrochemical behaviour at a liquid-organogel microinterface array of fucoidan extracted from algae

“…However, careful optimisation of the electrolyte and adsorption potential conditions might help to alleviate this problem, as reported previously for insulin detection in the presence of serum albumin. 61 …”

Recent developments in electrochemistry at the interface between two immiscible electrolyte solutions for ion sensing

“…Different fabrication strategies to prepare these µITIES exist and have been reviewed elsewhere. 20,22 ITIES of microscopic dimensions are now routinely used under the form of a single µITIES [43][44][45][46][47][48]37,[49][50][51] ( Figure 1D) or of an array of µITIES [52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] ( Figure 1E) allowing to reach limits of detection in the range of tens of nM with an analysis time of a couple of minutes. Diffusion of ionic species at µITIES has shown an asymmetric profile.…”

“…31,32,86 This experimental set-up could be used for the calibration-free determination of ion Target analytes. The sensing of molecules of biological interest (small organic molecules, 52,53,28,87 carbohydrates, 88,29 and proteins 26,[54][55][56]30,[57][58][59][60] ), synthetic organic molecules (drug molecules, 61,43,[62][63][64]81,89 pollutants 44,45,27,42 ) and inorganic species (both cations 36,46,31,32,47,48,33,37,38,49,65,34,39,40,51,50,66,41 and anions 67,35,68 ) has been extensively studied in the 2010-2015 period covered in thi...…”

Electrochemical signature of hen egg white lysozyme at the glycerol-modified liquid-liquid interface

“…Finally, the desorption-peak ( Figure 1a, reverse scan, 0.66 V) is associated with desorption of the HEWL/TPBClcomplex from the interface ( Figure 1, reverse scan). This desorption process may involve the decomplexation of the adsorbed species and the subsequent back-transfer of the organic phase anion, which provides the charge transfer step employed in detection of proteins by this approach [23][24][25], or simply the desorption of the complex to the bulk aqueous phase.…”