Molecularly imprinted polymer-based electrochemical sensors for biopolymers

Electrochemical synthesis and signal generation dominate among the almost 1200 articles published annually on protein-imprinted polymers. Such polymers can be easily prepared directly on the electrode surface, and the polymer thickness can be precisely adjusted to the size of the target to enable its free exchange. In this architecture, the molecularly imprinted polymer (MIP) layer represents only one ‘separation plate’; thus, the selectivity does not reach the values of ‘bulk’ measurements. The binding of target proteins can be detected straightforwardly by their modulating effect on the diffusional permeability of a redox marker through the thin MIP films. However, this generates an ‘overall apparent’ signal, which may include nonspecific interactions in the polymer layer and at the electrode surface. Certain targets, such as enzymes or redox active proteins, enables a more specific direct quantification of their binding to MIPs by in situ determination of the enzyme activity or direct electron transfer, respectively

Electrosynthesized molecularly imprinted polyscopoletin nanofilms for human serum albumin detection

Molecularly imprinted polymers (MIPs) rendered selective solely by the imprinting with protein templates lacking of distinctive properties to facilitate strong target-MIP interaction are likely to exhibit medium to low template binding affinities. While this prohibits the use of such MIPs for applications requiring the assessment of very low template concentrations, their implementation for the quantification of high-abundance proteins seems to have a clear niche in the analytical practice. We investigated this opportunity by developing a polyscopoletin-based MIP nanofilm for the electrochemical determination of elevated human serum albumin (HSA) in urine. As reference for a low abundance protein ferritin-MIPs were also prepared by the same procedure. Under optimal conditions, the imprinted sensors gave a linear response to HSA in the concentration range of 20–100 mg/dm3, and to ferritin in the range of 120–360 mg/dm3. While as expected the obtained limit of detection was not sufficient to determine endogenous ferritin in plasma, the HSA-sensor was successfully employed to analyse urine samples of patients with albuminuria. The results suggest that MIP-based sensors may be applicable for quantifying high abundance proteins in a clinical setting

Review of Electrochemically Triggered Macromolecular Film Buildup Processes and Their Biomedical Applications

International audienceMacromolecular coatings play an important role in many technological areas, ranging from the car industry to biosensors. Among the different coating technologies, electrochemically triggered processes are extremely powerful because they allow in particular spatial confinement of the film buildup up to the micrometer scale on microelectrodes. Here, we review the latest advances in the field of electrochemically triggered macromolecular film buildup processes performed in aqueous solutions. All these processes will be discussed and related to their several applications such as corrosion prevention, biosensors, antimicrobial coatings, drug-release, barrier properties and cell encapsulation. Special emphasis will be put on applications in the rapidly growing field of biosensors. Using polymers or proteins, the electrochemical buildup of the films can result from a local change of macromolecules solubility, self-assembly of polyelectrolytes through electrostatic/ionic interactions or covalent cross-linking between different macromolecules. The assembly process can be in one step or performed step-by-step based on an electrical trigger affecting directly the interacting macromolecules or generating ionic species

Electrochemical Biosensors Based on Molecularly Imprinted Polymer Biomimetic Receptors

Doctor of Philosophy (Chemistry), 2023This thesis presents the utilization of molecularly imprinted polymer (MIP) biomimetic receptors as recognition elements in the development of two MIP electrochemical biosensors. One is a MIP cryogel for the direct detection of insulin, performed in a flow system. The other is an electrochemical biosensor with dual MIPs for the simultaneous determination of creatinine and albumin to provide the albumin to creatinine ratio (ACR) value. The insulin sensor was prepared using a gold electrode modified with carboxylated multiwalled carbon nanotubes (f-MWCNTs) to provide a large surface area platform for the high loading of the MIP cryogel and to increase the conductivity of the sensor. The MIP cryogel porous structure provided a large number of the imprinted recognition sites and improved the access of insulin to/from the MIP cavities. In addition, the flow system facilitated the mass transfer and limited the non-specific binding. This MIP cryogel provided a 0.050-1.40 pM linear range and a low limit of detection (LOD) of 33 fM with good stability at room temperature. For the dual MIP sensor, it was prepared on the dual screen-printed carbon electrodes (SPdCEs) modified with f-MWCNTs and redox probes, polymethylene blue (PMB) and ferrocene (Fc). The surface imprinting and electropolymerization were carried out to obtain more controlled imprinted binding sites of the two analytes on the respective electrode. This sensor was able to selectively recognize the two analytes with linear ranges of 5.0-100 ng mL-1 and 100-2500 ng mL-1 for creatinine and 5.0-100 ng mL-1 for albumin with an LOD of 1.5±0.2 ng mL-1 and 1.5±0.3 ng mL-1, respectively. The two MIP electrochemical biosensors exhibited good reusability and the real sample detection results showed comparable performances to the clinically employed standard methods (P 0.05). The good performances of these MIP electrochemical biosensors, i.e., high sensitivity and selectivity, low limit of detection, and high stability indicate their potential as alternative methods for analysis

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

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)