Modern and Dedicated Methods for Producing Molecularly Imprinted Polymer Layers in Sensing Applications

Abstract

Molecular imprinting (MI) is the most available and known method to produce artificial recognition sites, similar to antibodies, inside or at the surface of a polymeric material. For this reason, scholars all over the world have found MI appealing, thus developing, in this past period, various types of molecularly imprinted polymers (MIPs) that can be applied to a wide range of applications, including catalysis, separation sciences and monitoring/diagnostic devices for chemicals, biochemicals and pharmaceuticals. For instance, the advantages brought by the use of MIPs in the sensing and analytics field refer to higher selectivity, sensitivity and low detection limits, but also to higher chemical and thermal stability as well as reusability. In light of recent literature findings, this review presents both modern and dedicated methods applied to produce MIP layers that can be integrated with existent detection systems. In this respect, the following MI methods to produce sensing layers are presented and discussed: surface polymerization, electropolymerization, sol–gel derived techniques, phase inversionand deposition of electroactive pastes/inks that include MIP particles.

Recent Trends in the Development of Carbon-Based Electrodes Modified with Molecularly Imprinted Polymers for Antibiotic Electroanalysis

“…The instrumentation used for sensing applications consists of the following interconnected parts: (1) a sensor, which is the sensing device composed of (i) a receptor (recognition element, e.g., the MIP) for the sensitive and selective detection of the target analyte in the presence of possible interfering species and (ii) a physical transducer (e.g., the electrode, like the GCE, on which the MIP was immobilized) that converts the chemical information into a measurable signal (in the case of electrochemical transducers this is a voltage or a current) [78], and (2) a suitable device (e.g., a computer running dedicated software) to process and offer the analytical information (Figure 3) [85]. MIP-based sensors were used in various detection methods (electrochemical, optical, fluorescence, ECL, surface plasmon resonance, ELISA) [81].…”

“…The surface imprinting method implies the formation of a pre-polymerization complex from the template molecule and the functional monomer on the surface of a solid substrate. After the initiator and a cross-linking agent are added, an imprinted polymer layer is formed at the substrate surface [85,123]. For example, CFZ or CFE (templates) were linked to the carboxylated-MWCNTs-modified GCE by covalent bonds between the -COOH groups of the MWCNTs and the -NH 2 group of CFZ/CFE after immersion of the electrode in the template solution for 4 h at room temperature.…”

“…The resulting electrode was immersed into a VAN solution to form a VAN-peptide complex (through five hydrogen bonds) and afterward, this electrode dopamine was electropolymerized to obtain the VAN-imprinted polymer. After the template extraction, the 3D cavities remained in polymeric film attached to the electrode surface [85,95]. Electropolymerization is easy to carry out and generates reproducible sizeand shape-controlled particles [84].…”

“…Template removal is a critical step in the preparation of most MIPs and the applied method is important because incomplete removal of the target molecules determines a low sensitivity and may lead to false-positive errors [85]. Sometimes, the polymer chain makes removal difficult, with the preservation of the formed polymeric structure, due to the links existing between the template and the MIP functional groups or due to sterically hindrance.…”

Molecularly Imprinted Polymer-Based Sensor for Electrochemical Detection of Cortisol

“…The additional components needed to generate MIPs are porogenic solvents. The selection of porogenic solvents for the electro-polymerization process is also still limited to phosphate-buffered saline (PBS) solutions suitable for biological research and capable of maintaining the properties of the dissolved molecules [ 78 ]. Although the bulk polymerization process often uses organic solvents such as chloroform, acetonitrile, dichloromethane, and methanol, the porogenic solvent still has limitations in the electro-polymerization process.…”