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During the last years, artificial nanostructured materials attracted increasing scientific interest due to some remarkable properties such as high surface-to-volume ratio, low cost and straightforward preparation and handling. Among others, such materials show high potential for highly selective recognition in different fields of Analytical Chemistry, such as chemical sensor design. Carrying forward the approach of molecular imprinting from bulk/thin film to nanoparticles is one possible way to actually achieve that goal. Recent years have hence seen substantial increase in the number of MIP nanoparticle publications. This review gives a detailed overview of established precipitation and microemulsion methods for synthesising molecularly imprinted polymer (MIP) nanoparticles (NPs) as well as giving an outlook on improving those by “living” polymerisation techniques to achieve controlled geometry and thickness as well as post-synthesis functionalisation. Besides these techniques, novel solid-phase imprinting approaches have recently emerged that show high potential for automatically synthesising MIP NP and transferring the protocols to large-scale production at reduced costs. In terms of sensor application, MIP NPs lead to appreciable sensitivity and selectivity. Moreover, nano-composite materials can be tailored to include additional functionality such as magnetic and semi-conductive cores. Within optical sensors, implementation of quantum dots (QDs) as optosensing material with a MIP shell even allows for fluorescence detection of non-optically active analytes. Sensitivity can be substantially improved by introducing Surface Plasmon Resonance (SPR) and Surface-Enhanced Raman Scattering (SERS), which have recently been successfully combined with MIP NPs and are promising chemical and biological sensors. Finally, MIP NPs have also proven very useful as plastic antibodies in pseudo-immunoassays.

Dimethyl methylphosphonate (DMMP) and Escherichia coli are mimics for chemical and biological agents, respectively. For designing robust sensor systems aiming at detecting them in real-life indoor environments, we designed artificial receptors based on bulk and surface imprinted polymers, respectively. Bulk-imprinted artificial recognition materials for DMMP yielded detection limits of 0.2 ppm in air on quartz crystal microbalance (QCM) sensor with selectivity factors of >40 towards indoor background contaminants, such as alcohols or acetic esters. The sensor layers retain their sensitivity for at least one year thus showing potential for maintenance-free long term sensing. They can be combined with pre-concentrator units to increase the overall performance of the system. Surface-imprinted polyurethanes optimized to selectively recognize E. coli showed ten times higher sensor responses on QCM than the respective non-imprinted polymers. Detection limits of these sensors turned out to be in the range of 0.1 mg/ml E. coli in aqueous solution. Different strains of this species (b and w, respectively) could be discriminated with selectivity factors of at least three thus implementing bioanalogous recognition in robust, man-made materials.