A Molecularly Imprinted Polymer Based Biosensor for Electrochemical Impedance Spectroscopic Analysis

Abstract

Biosensor, a device used in the detection of an analyte, combines a biological/chemical sensor component with a physicochemical transducer. The sensor and the transducer elements recognize and detect the analyte qualitatively and/or quantitatively [1][2][3]. The biological sensor element may be in the form of tissue, microorganism, organelle, receptor, enzyme, antibody, nucleic acid, molecule, etc., which may be attached to the metal, polymer or glass surface of the electrode through chemical and physical means.A biological sensor element may be relatively short-lived and with complications in handling; therefore, they may be replaced with artificial elements that are components of a receptor-based sensing system. Molecular Imprinting Technology (MIT) is a method that aims to overcome these complications by producing selectively specific artificial receptors. It utilizes molecular imprinting polymer (MIP), formed as a dependable molecular recognition element with room temperature stability that mimicks natural recognition elements, such as antibodies and receptors. MIT is used in the detection, separation and purification of biological and chemical molecules, such as amino acids and proteins, nucleotids, toxins, drugs, etc. A 3D polymeric network is formed between the analyte and monomer through functional hydrogen bonds, dipole-dipole and ionic interactions. After polymerization, upon removal of the analyte, specific recognition sites that are in the shape, size and chemical structure of the analyte are formed in the polymer [4][5][6][7][8][9][10][11].There are examples of MIP based sensors equipped more commonly with SPRS and QCM based transducers [4]. However, they have not been experimented in the detection of small ABSTRACTA molecularly imprinted polymer (MIP)-based impedimetric biosensor was developed for the electrochemical analysis of low-weight biological molecules. Synthetic polymeric matrices with specific and selective recognition sites, which are complementary to the shapes and sizes of the functional groups of analytes, can be prepared using the molecular imprinting method. In this study, a small molecule, tris(hydroxymethyl)aminomethane (TRIS), was used to coat a graphite pencil tip with a TRIS-containing polyacrylamide gel to fabricate a working electrode. The electrode modification and performance were evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical properties of the modified electrodes were observed using an electrochemical cell comprising a Ag/AgCl reference electrode, a Pt wire as the counter electrode, and a pencil graphite tip as the working electrode using a redox-phosphate buffer solution with different concentrations of TRIS and Ethylenediaminetetraacetic acid (EDTA). The I-V and impedance performance of the chemically modified graphite pencil-tip electrodes exhibited decreased conductance and increased impedance correlating with the increase in TRIS concentration. Thus, MIP-based small-molecule biosensor prototypes can be promising eco...