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.

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.

Sensing syringic acid in food samples is highly valuable in food quality control due to its health promoting effects. To this purpose, syringic acid MIPs aligning with green chemistry have been developed by employing a bio-based functional monomer as DES and ethanol-water as porogen. MIP was implemented into a low-cost thermal readout platform as functional layer utilizing carbon tape for deposition. The sensor was characterized using SEM, IR, TGA and laser diffraction and its performance was evaluated through loading assays with syringic acid solutions, selectivity studies using structural analogues and food components, and quantification of syringic acid in thyme and walnut benchmarked by LC-MS. This work is the first to accurately quantify a molecular target using thermal readout with resulting LOD and LOQ of 0.28 ± 0.06 and 0.84 ± 0.18 μM respectively, linear ranges between 0.5 - 2.5 μM and 2.5 - 17.5 μM and recoveries ranging between 96.0 - 111 %.

This work focuses on the pH‐triggered disassembly of supramacromolecular microgels, which are composed of the temperature‐responsive poly(N‐vinylcaprolactam) (PVCL) and the natural polyphenol tannic acid (TA). A systematic investigation of the microgel formation demonstrates that a retarded addition of tannic acid during semi‐batch precipitation polymerization influences the yield, chemical composition, and properties of the microgels to a great extent. Microgel properties, such as size, deformability, and chemical stability, can be easily tuned by varying the ratio between both building blocks PVCL and TA. Finally, the pH‐triggered disassembly of supramacromolecular microgels at different pH and temperatures demonstrates that their chemical structure can precisely control the degradation profile. Temperatures lower than the volume phase transition temperature (VPTT) of PVCL (T < 32 °C) and a pH > 10 result in a complete disassembly of the microgels into PVCL chains and TA due to the destruction of the hydrogen bonds responsible for the formation of a colloidal microgel. Interestingly, at temperatures above VPTT, the microgels keep their integrity due to enhanced hydrophobic interactions between the polymer chains of the microgel and are no longer affected by pH changes.

Xylazine adulterated Fentanyl is considered one of the deadliest drug threats ever faced in the United States. However, due to the complexity of the illegal drug supply, xylazine detection in the frame of drug-checking (harm reduction) remains an unsolved challenge, one which has cost numerous lives across North America. In this work, we present two sensor platforms for detecting xylazine in drug-checking applications. Both platforms are based on molecularly imprinted polymers (MIPs) using vinyl phosphonic acid as the main monomer. By combining the MIPs with thermometric and colorimetric readouts, we achieved xylazine detection in a wide concentration range, relevant in real-world scenarios. First, the heat-transfer method (HTM) allowed xylazine detection in the low concentration range within 15 min per concentration, with a limit of detection (LoD) of 16.5 ng/mL (75 nM). Second, a dye displacement assay employing methylene blue provided rapid ( 76 μg/mL-five times lower than the average concentration reported for street samples. Additionally, the colorimetric sensor exhibited potential for detecting various unwanted xylazine analogues, which could potentially act as fentanyl adulterants in the future. Most importantly, the colorimetric sensor consistently detected xylazine in a highly complex, street-like fentanyl sample containing five common interferents. The synergy of the proposed sensors offers a promising alternative for centralized and on-site xylazine screening in harm reduction settings.