Matoori, SimonMooney, David2021-04-132020-05-16Matoori, Simon and David J. Mooney. (2020). Near‐Infrared Fluorescence Hydrogen Peroxide Assay for Versatile Metabolite Biosensing in Whole Blood. Small 60, no. 20. doi:10.1002/smll.2020003691613-68101613-6829https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37367257In emergency medicine, blood lactate levels are commonly measured to assess the severity and response to treatment of hypoperfusion-related diseases (e.g., sepsis, trauma, cardiac arrest). Clinical blood lactate testing is conducted with laboratory analyzers, leading to a delay of three hours between triage and lactate result. Here we describe a fluorescence-based blood lactate assay, which could be utilized for bedside testing, based on measuring the hydrogen peroxide generated by the enzymatic oxidation of lactate. To establish a hydrogen peroxide assay, near-infrared cyanine derivatives were screened and sulfo-cyanine 7 was identified as a new HRP substrate, which loses its fluorescence in presence of HRP and hydrogen peroxide. As hydrogen peroxide is rapidly cleared by erythrocytic catalase and glutathione peroxidase, sulfo-cyanine 7, HRP, and lactate oxidase were encapsulated in a liposomal reaction compartment. In lactate-spiked bovine whole blood, the newly developed lactate assay exhibited a linear response in a clinically relevant range after 10 min. Substituting lactate oxidase with glucose and alcohol oxidase allowed for blood glucose, ethanol, and methanol biosensing, respectively. This easy-to-use, rapid, and versatile assay may be useful for the quantification of a variety of enzymatically oxidizable metabolites, drugs, and toxic substances in blood and potentially other biological fluids.en-UShydrogen peroxidelactateliposomenear-infrared dyessulfo-cyanine 7Journal Article2021-04-13