Electrochemically synthesized polymers in molecular imprinting for chemical sensing

This critical review describes a class of polymers prepared by electrochemical polymerization that employs the concept of molecular imprinting for chemical sensing. The principal focus is on both conducting and nonconducting polymers prepared by electropolymerization of electroactive functional monomers, such as pristine and derivatized pyrrole, aminophenylboronic acid, thiophene, porphyrin, aniline, phenylenediamine, phenol, and thiophenol. A critical evaluation of the literature on electrosynthesized molecularly imprinted polymers (MIPs) applied as recognition elements of chemical sensors is presented. The aim of this review is to highlight recent achievements in analytical applications of these MIPs, including present strategies of determination of different analytes as well as identification and solutions for problems encountered

Polymers imprinted with three REG1B peptides for electrochemical determination of Regenerating Protein 1B, a urinary biomarker for pancreatic ductal adenocarcinoma

Three peptides (each containing 13–18 amino acids) were synthesized and used as templates for molecular imprinting and epitope recognition of the Regenerating Protein 1B (REG1B), which is one of the urinary biomarkers for pancreatic ductal adenocarcinoma (PDAC). Poly(ethylene-co-vinyl alcohol)s were employed as the host for molecular imprinting of the peptides. Following their preparation, the molecularly imprinted polymers (MIP) were examined by cyclic voltammetry. The electrochemical responses of a screen-printed gold substrate coated with the MIP were measured at a working voltage of 300 mV (vs. Ag/AgCl); the entire protein and the peptides gave similar responses at concentrations of <1.0 pg⋅mL−1, with detection limits as low as 0.1 pg⋅mL−1. Urine samples from healthy and PDAC patients were then analyzed by using this modified gold electrode, and the results are in agreement with data obtained with ELISA

Solubility and size of polymer nanoparticles

The solubility of polymer nanoparticles is a complex phenomenon dependent on solvent–solute and solute–solute interactions. Contrary to phase separation in standard polymerization reactions, which is a well established research area, the relationship between the solubility of polymer nanoparticles and the resulting diameter of the nanoparticles has been largely overlooked. Herein we demonstrate that the absolute size of polymer nanoparticles can be predicted (and controlled) by varying the relevant parameters of the polymerization conditions that influence the solubility and Flory parameter, χs, p. The position of the spinodal, associated with a given χs, p equivalent and determined with a simple thermodynamic model, allows an absolute value, Δχspinodal, to be applied in predicting polymer dimensions. The hydrodynamic diameter of particles at the primarily observed fraction was found to be dependent on D (nm) = −74Δχspinodal + 367 nm, where Δχspinodal must be positive for successful separation. Variation with total polymer fraction over a limited range can also be observed to follow a trend of approximately D (nm) = 173 ln[(xN)2 10−36/Δχspinodal] − 193 nm, thus giving a more general description of polymerization. We also assert the importance of separating spinodal-character phase separation from binodal-character phase separation in polymer nanoparticle synthesis. To the best of our knowledge this is the first successful Flory–Huggins based thermodynamic model of polymer nanoparticles, and should provide a useful guide to predictive design of future nanomaterial

Molecularly imprinted polymers for the recognition of proteins: The state of the art.

Molecular imprinting has proved to be an effective technique for the creation of recognition sites on a polymer scaffold. Protein imprintinghas been a focus for many chemists working in the area of molecular recognition, since the creation of synthetic polymers that can specificallyrecognise proteins is a very challenging but potentially extremely rewarding objective. It is expected that molecularly imprinted polymers (MIPs)with specificity for proteins will find application in medicine, diagnostics, proteomics, environmental analysis, sensors and drug delivery. In thisreview, the authors provide an overview of the progress achieved in the decade between 1994 and 2005, with respect to the challenging area of MIPsfor protein recognition. The discussion furnishes a comparative analysis of different approaches developed, underlining their relative advantagesand disadvantages and highlighting trends and possible future directions

Surface grafted molecularly-imprinted polymers for protein recognition.

A technique for coating microplate wells with molecularly imprinted polymers (MIP's) specific for proteins is presented. 3-Aminophenylboronic acid was polymerized in the presence of the following templates: microperoxidase, horseradish peroxidase, lactoperoxidase, and hemoglobin, via oxidation of the monomer by ammonium persulfate. This process resulted in the grafting of a thin polymer layer to the polystyrene surface of the microplates. Imprinting resulted in an increased affinity of the polymer toward the corresponding templates. The influence of the washing procedure, template concentration, and buffer pH on the polymer affinity was analyzed. It was shown that the stabilizing function of the support and spatial orientation of the polymer chains and template functional groups are the major factors affecting the imprint formation and template recognition. Easy preparation of the MIPs, their high stability, and their ability to recognize small and large proteins, as well as to discriminate molecules with small variations in charge, make this approach attractive and broadly applicable in biotechnology, assays and sensors

On the properties of poly-aminophenylboronate coatings in capillary electrophoresis for the selective separation of small diol-containing analytes and glycoproteins.

The polymerisation of 3-aminophenylboronic acid (APBA) in aqueous environment has been used for the open tubular modification of capillary electrophoresis (CE) capillaries. Being poly-APBA endowed with boronic acid, aromatic rings and secondary amines groups, it posses a variety of functional groups affecting selectivity. Diastereoisomers (e.g. ascorbic and isoascorbic acid) and proteins (e.g. haemoglobins) were successfully separated onto poly-APBA column, by means of a combination of electrophoresis and open tubular electrochromatography. The mechanism of selection was investigated: results indicate an interplay between enhancing or silencing the contribution of the protonable functionahties (amino groups, boronic acid). The properties of APBA polymer coating make it attractive for CE separation and for further application in affinity separations and chip technologies. (C) 2003 Elsevier B.V. All rights reserved

Substitution of antibodies and receptors with molecularly imprinted polymers in enzyme-linked and fluorescent assays.

A new technique for coating microtitre plates with molecularly imprinted polymers (MIP), specific for low-molecular weight analytes (epinephrine, atrazine) and proteins is presented. Oxidative polymerization was performed in the presence of template; monomers: 3-aminophenylboronic acid (APBA), 3-thiopheneboronic acid (TBA) and aniline were polymerized in water and the polymers were grafted onto the polystyrene surface of the microplates. It was found that this process results in the creation of synthetic materials with antibody-like binding properties. It was shown that the MIP-coated microplates are particularly useful for assay development. The high stability of the polymers and good reproducibility of the measurements make MIP coating an attractive alternative to conventional antibodies or receptors used in enzyme linked immunosorbent assay (ELISA)