Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose

Multilocus Distance-Regulated Sensor Array for Recognition of Polyphenols via Machine Learning and Indicator Displacement Assay

Developing new strategies to construct sensor arrays that can effectively distinguish multiple natural components with similar structures in mixtures is an exceptionally challenging task. Here, we propose a new multilocus distance-modulated indicator displacement assay (IDA) strategy for constructing a sensor array, incorporating machine learning optimization to identify polyphenols. An 8-element array, comprising two fluorophores and their six dynamic covalent complexes (C1-C6) formed by pairing two fluorophores with three distinct distance-regulated quenchers, has been constructed. Polyphenols with diverse spatial arrangements and combinatorial forms compete with the fluorophores by forming pseudocycles with quenchers within the complexes, leading to varying degrees of fluorescence recovery. The array accurately and effectively distinguished four tea polyphenols and 16 tea varieties, thereby demonstrating the broad applicability of the multilocus distance-modulated IDA array in detecting polyhydroxy foods and natural medicines.

Electrochemical quantification of Ag2S quantum dots: evaluation of different surface coating ligands for bacteria determination

In this work, novel silver sulphide quantum dots (Ag₂S QD) are electrochemically quantified for the first time. The method is based on the electrochemical reduction of Ag⁺ to Ag⁰ at -0.3 V on screen-printed carbon electrodes (SPCEs), followed by anodic stripping voltammetric oxidation that gives a peak of currents at +0.06 V which represents the analytical signal. The optimized methodology allows the quantification of water-stabilized Ag₂S QD in the range of approximately 2 × 10⁹-2 × 10¹² QD·mL^-1 with a good reproducibility (RSD: 5%). Moreover, as proof-of-concept of relevant biosensing application, Ag₂S QD are evaluated as tags for Escherichia coli (E. coli) bacteria determination. Bacteria tagged with QD are separated by centrifugation from the sample solution and placed on the SPCE surface for quantitative analysis. The effect of two different Ag₂S QD surface coating/stabilizing agents on both the voltammetric response and the bacteria sensing is also evaluated. 3-mercaptopropionic acid (3-MPA) is studied as model of short length coating ligand with no affinity for the bacteria, while boronic acid (BA) is evaluated as longer length ligand with chemical affinity for the polysaccharides present in the peptidoglycan layer on the bacteria cells surface. The biosensing system allows to detect bacteria in the range 10^-1-10³ bacteria·mL^-1 with a limit of detection as low as 1 bacteria·mL^-1. This methodology is a promising proof-of-concept alternative to traditional laboratory-based tests, with good sensitivity and short time and low cost of analysis. Graphical abstractNovel silver sulphide quantum dots (Ag₂S QD) are electrochemically quantified for the first time. Moreover, Ag₂S QD are evaluated as tags for Escherichia coli bacteria determination. The effect of two different QD surface coating ligands is also evaluated.

Tests of intestinal mucosal hyperpermeability: Many diseases, many biomarkers and a bright future

The number of disorders now linked to increased intestinal mucosal permeability implies that a substantial percent of the population is affected. Drug interventions targeting reduced tight junctional permeability are being pursued. Although hyper-permeability in itself is not a clinically recognized disease entity, its relationship to disease processes has driven interest in measuring, and even monitoring mucosal permeability in vivo. Along with improved knowledge of gut barrier physiology, advances have been made in tests and biomarkers of barrier function. Drawing from our experiences in the past decade, considerations and challenges faced in assessing in vivo intestinal permeability are discussed herein, along with indications of what the future might hold.