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Molecular recognition has been described as the “ultimate” form of sensing and plays a fundamental role in biological processes. There is a move towards biomimetic recognition elements to overcome inherent problems of natural receptors such as limited stability, high-cost, and variation in response. In recent years, several alternatives have emerged which have found their first commercial applications. In this review, we focus on molecularly imprinted polymers (MIPs) since they present an attractive alternative due to recent breakthroughs in polymer science and nanotechnology. For example, innovative solid-phase synthesis methods can produce MIPs with sometimes greater affinities than natural receptors. Although industry and environmental agencies require sensors for continuous monitoring, the regulatory barrier for employing MIP-based sensors is still low for environmental applications. Despite this, there are currently no sensors in this area, which is likely due to low profitability and the need for new legislation to promote the development of MIP-based sensors for pollutant and heavy metal monitoring. The increased demand for point-of-use devices and home testing kits is driving an exponential growth in biosensor production, leading to an expected market value of over GPB 25 billion by 2023. A key requirement of point-of-use devices is portability, since the test must be conducted at “the time and place” to pinpoint sources of contamination in food and/or water samples. Therefore, this review will focus on MIP-based sensors for monitoring pollutants and heavy metals by critically evaluating relevant literature sources from 1993 to 2022.

Molecular imprinted polymer (mip) sensors offer a high potential in the development of cheap small-scale disposable biomimetic sensors. Molecular imprinting leads to the formation of inert polymer particles with nanocavities, which can exhibit similar selectivity and specificity to target molecules as antibodies or enzymes. These sensors open up many possible applications in the field of mass-market consumer products such as food packaging sensors. One such application is the detection of histamine in spoiled fish, which causes scombroid poisoning, a common seafood poisoning. This contribution provides one possible solution for easing the use of these sensors in field applications. A screen-printed short-range wireless mip-based biosensor based upon passive radio frequency identification (rfid) tags was developed as a proof of principle. Histamine molecules binding to an mip recognition layer induce a dielectric change in the sensor capacitance, resulting in a resonance frequency shift that is transmitted by inductive coupling. This wireless sensor is capable of detecting histamine concentrations as low as 50 nm at a range of a few centimeters.

A miniaturised, low cost impedance analyser is developed to ease the use of impedance spectroscopy in biological setups. This could form the first step towards fully standalone, hand-held biosensor applications. The system is capable of performing quasi-simultaneous time resolved impedance measurements on eight different channels in a frequency range of 10Hz-100kHz. The unit is accurate in a broad impedance range and is able to perform stable measurements over intervals of several days. The system is characterised by passive components, a temperature controlled wet cell based impedance setup and a biomimetic molecularly imprinted polymer (MIP) based histamine sensor. The test results all indicate accurate and stable functioning of the unit, making it suitable for bioanalytical applications. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. ispartof: Physica Status Solidi A, Applications and Materials Research vol:208 issue:6 pages:1357-1363 status: published

In dieser Arbeit wurden fluoreszierende MIP-Partikel hergestellt, um polare Analyten von biologischer und ökologischer Bedeutung zu analysieren, zum Beispiel den Krebs-Biomarker Sialinsäure (SA) und die Herbizide Glyphosat (GPS), Haloxyfop P und Fenoxaprop P. Die MIP-Schale wurde auf Siliziumdioxid und siliziumdioxid-beschichtete Polystyrol (PS)-Kernpartikel synthetisiert und enthielt einen Fluoreszenzfarbstoff, dessen Signal in Anwesenheit der Zielanalyten verstärkt wurde. Die Leistungsfähigkeit aller MIP-Partikel wurde durch den Vergleich ihres Bindungsverhaltens mit den nicht geprägten Polymer (NIP)-Partikeln und/oder durch ihre Diskriminierungsfähigkeit gegenüber konkurrierenden Analyten bewertet. Fluoreszierende Monomer für die MIP-Synthese erwiesen sich als vorteilhaft, da sowohl die Bindungsleistung als auch die Assoziationskonstanten einfacher bestimmt werden konnten. Als Alternative zur traditionellen Wasserstoffbrückenbindung zwischen Analyt und Bindungseinheit des Farbstoffes in unpolaren Lösungsmitteln, kann die Deprotonierung-Protonierung von harnstoffhaltigen Farbstoffen als Sensing-Mechanismus in polaren Medien wie DMF verwendet werden. Darüber hinaus führte die Verwendung eines „Dummy“-Analyten für die NIP-Partikel-Synthese zu einer Polymerschicht mit ähnlichen Eigenschaften wie die der MIP-Partikel, womit "Dummy"-NIPs als deutlich bessere Kontrollpartikel herangezogen werden konnten. Insgesamt erwies sich die Bestimmung der Diskriminierung der MIPs gegenüber konkurrierenden Analyten als konsistenteres Maß für die Leistungsbeurteilung. Mit Siliziumdioxid beschichtete, farbstoffdotierte PS-Partikel erwiesen sich als vielseitige Plattform für das Aufwachsen fluoreszierender MIP-Schalen, um zweifach fluoreszierende MIPs zu erhalten. Das Vorhandensein eines Kontrollsignals ist vorteilhaft für die Korrektur instrumenteller Schwankungen während analytischer Tests., Fluorescent MIP particles were prepared to target highly polar analytes of biological and environmental significance, namely sialic acid (SA) and glyphosate (GPS), haloxyfop P and fenoxaprop P. Silica and silica-coated polystyrene (PS) particles were used as core supports on which a MIP shell was synthesized. In all systems, the MIP shell contained a fluorescent dye with urea sensing motifs whose signal was enhanced in the presence of the target analyte. The performance of all MIP particles was evaluated by comparing their binding behaviour to that of non-imprinted polymer (NIP) controls and/or determining their discrimination ability against competing analytes. It was found that the application of fluorescent monomers in MIP synthesis is advantageous due to simplified determination of binding performance and binding parameters such as association constants. It was also shown that deprotonation-reprotonation of urea containing dyes can be used as a sensing mechanism in polar media such as DMF, as an alternative to traditional hydrogen bonding in non-polar aprotic solvents. In addition, the results showed that the inclusion of a “dummy” template during NIP synthesis led to the formation of a polymer layer with similar properties as the MIP, and thus, “dummy” NIPs provided a more relevant comparison for MIP binding. Overall, the discrimination of MIPs against competing analytes was found to be a more consistent measure of MIP performance. When a urea containing dye was used to prepare MIPs targeting anions by hydrogen bonding in non-polar media, the choice of counterion used during imprinting influenced the binding behaviour of the resulting MIPs and must be carefully chosen. Lastly, silica-coated dye-doped PS was found to be a versatile platform for the grafting of fluorescent MIP shells to achieve dual fluorescent MIPs, and the presence of a control signal was beneficial in correcting instrumental fluctuations during analytical assays.