Boronic Acid-Based\nGlucose Detection for Liver Three-Dimensional\nCellular Models

Liver 3D cell models are regularly employed as a screening\nplatform\nfor predicting the metabolic safety of drugs, by monitoring the physiological\nresponses of the spheroids, through the measurement of relevant markers\nof normal liver physiology, notably glucose. Measuring glucose levels\nwithin the spheroids and their surroundings provides insight into\nthe metabolic homeostasis of liver cells and may be employed as an\nindication of potential drug-induced toxicity. Several ortho-aminomethyl\nphenylboronic acid (PDBA) glucose sensors have been developed. Most\nrecently, Mc-CDBA ((((((2-(methoxycarbonyl)anthracene-9,10-diyl)bis(methylene))\nbis(methylazanediyl))bis(methylene))bis(4-cyano-2,1-phenylene))diboronic\nacid) was reported. Although Mc-CDBA exhibits good water solubility\nand sensitivity toward glucose, its ability for intra- and extracellular\nglucose monitoring in spheroids has not been determined. Here, we\npresent a set of Mc-CDBA derivatives: carboxylic (BA) and amide (BA\n5)-based Mc-CDBA sensors for extra- and intracellular glucose monitoring,\nrespectively. Both sensors exhibit superior spectroscopic features.\nBA 5 showed selective intracellular accumulation in liver spheroids\nand exhibited more than 3-fold higher basal fluorescence sensitivity\ncompared to Mc-CDBA. These observations led to the development of\nan extracellular hydrogel-embedded sensor (HG-BA 21) to monitor extracellular\nglucose levels under persistent solution flow mimicking physiological\nconditions. We have therefore demonstrated that the sensors developed\nby our team are suitable for a variety of assays, notably with liver\nspheroids, and provide powerful new tools for organ-on-a-chip applications\npredicting drug-induced liver injury in the early stages of drug development.