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The paper is a self-review of works on development of new approaches to formation of mimics of receptor and catalytic sites of biological macromolecules in the structure of highly cross-linked polymer membranes and thin films. The general strategy for formation of the binding sites in molecularly imprinted polymer (MIP) membranes and thin films was described. A selective recognition of a number of food toxins, endocrine disruptors and metabolites is based on the results of computational modeling data for the prediction and optimization of their structure. A strategy proposed for the design of the artificial binding sites in MIP membranes was supported by the research performed by the authors on development of a number of the MIP membrane-based affinity and catalytic biosensors for selective and sensitive measurement (detection limits 0.3–100 nM) of the target analytes. Novel versatile approaches aimed at improving sensitivity of the developed biosensor systems were discussed.

Sucrose is a primary metabolite in plants, a source of energy, a source of carbon atoms for growth and development, and a regulator of biochemical processes. Most of the traditional analytical chemistry methods for sucrose quantification in plants require sample treatment (with consequent tissue destruction) and complex facilities, that do not allow real-time sucrose quantification at ultra-low concentrations (nM to pM range) under in vivo conditions, limiting our understanding of sucrose roles in plant physiology across different plant tissues and cellular compartments. Some of the above-mentioned problems may be circumvented with the use of bio-compatible ligands for molecular recognition of sucrose. Nevertheless, problems such as the signal-noise ratio, stability, and selectivity are some of the main challenges limiting the use of molecular recognition methods for the in vivo quantification of sucrose. In this review, we provide a critical analysis of the existing analytical chemistry tools, biosensors, and synthetic ligands, for sucrose quantification and discuss the most promising paths to improve upon its limits of detection. Our goal is to highlight the criteria design need for real-time, in vivo, highly sensitive and selective sucrose sensing capabilities to enable further our understanding of living organisms, the development of new plant breeding strategies for increased crop productivity and sustainability, and ultimately to contribute to the overarching need for food security.

In this paper for the first time we successfully detect bacterial flagellar filaments from Proteus mirabilis using molecularly imprinted artificial receptors. These receptors acted as a sensing layer of the biosensors, assembled by imprinting flagellar proteins onto a polymeric backbone of electropolymerized phenol. In short, flagellar filaments were absorbed onto a carbon support, phenol was electropolymerized around it through the carbon conductive matrix to create the protein molecular molds, and finally the flagellar proteins were removed by enzymatic and electrochemical action. Each removed flagellar protein gave rise to an imprinted site with eventual rebinding ability. Electrical impedance spectroscopy (EIS) and square wave voltammetry (SWV) were employed to measure the interaction of flagellar filaments with the sensing layer assembled on commercial screen-printed electrodes, providing low detection limits, high precision and selectivity toward the targeted protein. The detection limit was 0.7 ng/mL by EIS and 0.9 ng/mL by SWV. The artificial receptors were further assembled on home-made paper-printed electrodes, with the three-electrode system printed on a paper substrate, offering the possibility of detecting flagellar filaments at as low as 0.6 ng/mL with a disposable and cost-effective portable device. To the best of our knowledge this is the first sensing device where molecularly imprinted artificial receptors are tailored on home-made electrode based on paper substrates with three electrodes assembled together, which is a suitable approach for the fabrication of easy and cost-effective tailored electrodes. [ABSTRACT FROM AUTHOR]

Phenolic compounds are secondary metabolites frequently found in plants that exhibit many different effects on human health. Because of the relevant bioactivity, their identification and quantification in agro-food matrices as well as in biological samples are a fundamental issue in the field of quality control of food and food supplements, and clinical analysis. In this review, a critical selection of sensors and biosensors for rapid and selective detection of phenolic compounds is discussed. Sensors based on electrochemistry, photoelectrochemistry, fluorescence, and colorimetry are discussed including devices with or without specific recognition elements, such as biomolecules, enzymes and molecularly imprinted materials. Systems that have been tested on real matrices are prevalently considered but also techniques that show potential development in the field. [ABSTRACT FROM AUTHOR]