Joseph W. Lowdon

The versatility of molecularly imprinted polymers (MIPs) has led to their integration into applications like biosensing, separation, environmental monitoring, and drug delivery technologies. This diversity of applications has resulted in a plethora of synthesis approaches to precisely tailor the materials’ properties to the specific demands. A critical, yet often overlooked, factor in MIP synthesis is the choice of porogen. Porogens play a pivotal role in defining the morphology, surface properties, swelling behavior, and binding efficiencies of the resulting MIPs. While aprotic solvents have traditionally been the standard in molecular imprinting, recent developments have expanded the variety of employed porogens accompanied by notable improvements in MIP performance. Therefore, this review aims to highlight both traditional and emerging types of porogens used in molecular imprinting, their influence on polymer properties and sorption performance, and their application across various sensing and extraction applications.

Antimicrobial resistance (AMR) poses a significant threat to global health, powered by pathogens that become increasingly proficient at withstanding antibiotic treatments. This review introduces the factors contributing to antimicrobial resistance (AMR), highlighting the presence of antibiotics in different environmental and biological matrices as a significant contributor to the resistance. It emphasizes the urgent need for robust and effective detection methods to identify these substances and mitigate their impact on AMR. Traditional techniques, such as liquid chromatography-mass spectrometry (LC-MS) and immunoassays, are discussed alongside their limitations. The review underscores the emerging role of biosensors as promising alternatives for antibiotic detection, with a particular focus on electrochemical biosensors. Therefore, the manuscript extensively explores the principles and various types of electrochemical biosensors, elucidating their advantages, including high sensitivity, rapid response, and potential for point-of-care applications. Moreover, the manuscript investigates recent advances in materials used to fabricate electrochemical platforms for antibiotic detection, such as aptamers and molecularly imprinted polymers, highlighting their role in enhancing sensor performance and selectivity. This review culminates with an evaluation and summary of commercially available and spin-off sensors for antibiotic detection, emphasizing their versatility and portability. By explaining the landscape, role, and future outlook of electrochemical biosensors in antibiotic detection, this review provides insights into the ongoing efforts to combat the escalating threat of AMR effectively.

Per- and polyfluoroalkyl substances (PFAS) are a class of materials that have been widely used in the industrial production of a wide range of products. After decades of bioaccumulation in the environment, research has demonstrated that these compounds are toxic and potentially carcinogenic. Therefore, it is essential to map the extent of the problem to be able to remediate it properly in the next few decades. Current state-of-the-art detection platforms, however, are lab based and therefore too expensive and time-consuming for routine screening. Traditional biosensor tests based on, e.g., lateral flow assays may struggle with the low regulatory levels of PFAS (ng/mL), the complexity of environmental matrices and the presence of coexisting chemicals. Therefore, a lot of research effort has been directed towards the development of biomimetic receptors and their implementation into handheld, low-cost sensors. Numerous research groups have developed PFAS sensors based on molecularly imprinted polymers (MIPs), metal–organic frameworks (MOFs) or aptamers. In order to transform these research efforts into tangible devices and implement them into environmental applications, it is necessary to provide an overview of these research efforts. This review aims to provide this overview and critically compare several technologies to each other to provide a recommendation for the direction of future research efforts focused on the development of the next generation of biomimetic PFAS sensors.

Molecular Imprinted Polymers (MIPs) are well known for their specific recognition of a wide variety of different analytes. However, the complex immobilization process of MIPs onto sensor electrodes poses a significant challenge. This research introduces a novel approach to enhance the application potential of MIPs by exploiting dye-displacement MIPs. These synthetic receptors can selectively release dye upon exposure to an aqueous target. A disposable and low-cost lab-on-chip cartridge is presented, enabling the MIPs to interact with the target solution for dye displacement. Furthermore, these cartridges are coupled to a portable optical sensor setup that can be used for screening samples in a user-friendly and fast manner. Characterization experiments demonstrate the capability of the spectrometer setup to identify different color dyes and intensities. Finally, a proof-of-application shows the use of our sensing setup for the indirect detection of 2-methoxphenidine (2-MXP) using dye-loaded MIPs, employing a dose-response characterization (4PL). Furthermore, as the dye displacement and sensing principle are universal, this setup holds promise for various other sensing applications, including food quality assessment, environmental testing, and pharmaceutical analysis.

Glucose biosensors play an extremely important role in health care systems worldwide. Therefore, the field continues to attract significant attention leading to the development of innovative technologies. Due to their characteristics, Molecularly Imprinted Polymers (MIPs) represent a promising alternative to commercial enzymatic sensors. In this work, a low‐cost, flexible MIP‐based platform for glucose sensing by integrating MIP particles directly into screen‐printed electrodes (SPEs) is realized. The sensor design allows the detection of glucose via two different transducer principles, the so‐called “heat‐transfer method” (HTM) and electrochemical impedance spectroscopy (EIS). The sensitivity and selectivity of the sensor are demonstrated by comparing the responses obtained toward three different saccharides. Furthermore, the application potential of the MIP‐SPE sensor is demonstrated by analyzing the response in urine samples, showing a linear range of 14.38–330 µm with HTM and 1.37–330 µm with EIS. To bring the sensor closer to a real life application, a handheld dipstick sensor is developed, allowing the single‐shot detection of glucose in urine using EIS. This study illustrates that the simplicity of the dipstick readout coupled with the straightforward manufacturing process opens up the possibility for mass production, making this platform a very attractive alternative to commercial glucose sensors.

Offering high specificity and selectivity, molecularly imprinted polymers (MIPs) are synthetic polymeric affinity reagents that have become increasingly popular over the last couple of decades. Due to their long‐term chemical and physical stability and low production cost, they have become an increasingly popular choice of receptor in the realm of sense. MIPs have therefore been associated with the detection of small molecules, proteins, cells, and pathogens, proving a highly robust and useful tool in the production of next‐gen sensing platforms. This said, the development of these sensors pivots on one simple fact; these receptors have to be deposited onto a substrate for their desired application. The deposition of MIPs during sensor fabrication is therefore of great importance, with the field utilizing an array of mechanical and chemical deposition methods to achieve this. To this end, this review, therefore, sets aim at coalescing these different deposition approaches, classifying them, and outlining their utility when it comes to receptor design and integration. Thus, offering a knowledge base on current deposition methods, potential future approaches and analyzing where the MIP deposition field is tending toward.

Molecularly imprinted polymers (MIPs) have gained growing interest among researchers worldwide, due to their key features that make these materials interesting candidates for implementation as receptors into sensor applications. In fact, MIP-based glucose sensors could overcome the stability issues associated with the enzymes present in commercial glucose devices. Various reports describe the successful development of glucose MIPs and their coupling to a wide variety of transducers for creating sensors that are able to detect glucose in various matrices. In this review, we have summarized and critically evaluated the different production methods of glucose MIPs and the different transducer technologies used in MIP-based glucose sensors, and analyzed these from a commercial point of view. In this way, this review sets out to highlight the most promising approaches in MIP-based sensing in terms of both manufacturing methods and readout technologies employed. In doing so, we aim at delineating potential future approaches and identifying potential obstacles that the MIP-sensing field may encounter in an attempt to penetrate the commercial, analytical market.

In recent years, melamine-sensing technologies have increasingly gained attention, mainly due to the misuse of the molecule as an adulterant in milk and other foods. Molecularly imprinted polymers (MIPs) are ideal candidates for the recognition of melamine in real-life samples. The prepared MIP particles were incorporated into a thermally conductive layer via micro-contact deposition and its response towards melamine was analyzed using the heat-transfer method (HTM). The sensor displayed an excellent selectivity when analyzing the thermal response to other chemicals commonly found in foods, and its applicability in food safety was demonstrated after evaluation in untreated milk samples, demonstrating a limit of detection of 6.02 μM. As the EU/US melamine legal limit in milk of 2.5 mg/kg falls within the linear range of the sensor, it can offer an innovative solution for routine screening of milk samples in order to detect adulteration with melamine. The results shown in this work thus demonstrate the great potential of a low-cost thermal platform for the detection of food adulteration in complex matrices.

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.