Molecularly Imprinted Electropolymer for a Hexameric Heme Protein with Direct Electron Transfer and Peroxide Electrocatalysis

Abstract

For the first time a molecularly imprinted polymer (MIP) with direct electron transfer (DET) and bioelectrocatalytic activity of the target protein is presented. Thin films of MIPs for the recognition of a hexameric tyrosine-coordinated heme protein (HTHP) have been prepared by electropolymerization of scopoletin after oriented assembly of HTHP on a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold electrodes. Cavities which should resemble the shape and size of HTHP were formed by template removal. Rebinding of the target protein sums up the recognition by non-covalent interactions between the protein and the MIP with the electrostatic attraction of the protein by the SAM. HTHP bound to the MIP exhibits quasi-reversible DET which is reflected by a pair of well pronounced redox peaks in the cyclic voltammograms (CVs) with a formal potential of −184.4 ± 13.7 mV vs. Ag/AgCl (1 M KCl) at pH 8.0 and it was able to catalyze the cathodic reduction of peroxide. At saturation the MIP films show a 12-fold higher electroactive surface concentration of HTHP than the non-imprinted polymer (NIP).

Electrosynthesized molecularly imprinted polyscopoletin nanofilms for human serum albumin detection

“…While several electropolymerizable monomers emerged for protein imprinting applications [12] for preparing the HSA-imprinted MIP we used scopoletin as monomer, which has been introduced by Gajovich-Eichelmann [34] for the electrosynthesis of protein-MIPs and proved to enable the recognition of several protein targets. [34][35][36][37][38] By electropolymerization scopoletin forms an insulating polymer film, the thickness of which can be tuned to match the characteristic dimensions of the protein. The protein binding to the MIP was detected by measuring the oxidative current of a redox probe on the underlying electrode, i.e., the protein binding hinders the permeability of the redox probe through the MIP nanofilm.…”

Electrosynthesized MIPs for transferrin: Plastibodies or nano-filters?

“…The DET and the bioelectrocatalysis achieved by proteins at MIP-covered electrodes is in fact hardly possible if the respective globular proteins would not approach the surface of the protein-imprinted electrodes (Bosserdt et al, 2013) (Peng et al, 2016). In the present study the chemisorption via SH-groups explains the strong binding of urease to both the bare and the MIP covered Au-electrode as well as the incomplete removal of Trf from both electrode types as it is demonstrated by SEIRAS.…”

“…For the presented Trf-MIP the linear measuring range and the K d for Trf obtained by SWV of a redox marker and SPR are in the lower micromolar concentration range, i.e. comparable with scopoletin-based MIPs for cyt c (Bosserdt et al, 2013), concanavalin A (Dechtrirat et al, 2014) and HTHP (Peng et al, 2016) where a SAM prevents any direct binding to the Au-surface. Thus the binding sites in this study seem not to be affected significantly by electrode-protein interaction (Table S2).…”

Enzymes as Tools in MIP-Sensors

“…Two major principles have been applied: (i) Electroactive targets, such as morphine, paracetamol, tamoxifen, and diclofenac can permeate through the cavities of the MIP to the electrode and an electrochemical signal can be generated by the conversion of the target using different electrochemical methods. This principle has been frequently used for drugs which contain phenolic structures but also for a few proteins which show direct electron transfer, e.g., cytochrome c, hemoglobin, and hexameric tyrosinecoordinated heme protein (HTHP) [21,70,71]. (ii) Binding of the target modulates the diffusive permeation of redox markers in a concentrationdependent manner.…”

“…Some ten percent of MIP papers describe artificial receptors for proteins [7,[10][11][12][13], including enzymes [13][14][15][16][17][18][19][20][21]. Molecularly imprinted polymers have been mostly developed for binding of targets, thus mimicking the function of antibodies.…”