Biophysical profiling of tissue hypoxia via delayed luminescence of erythrosine

Abstract

This study investigated the kinetics of delayed erythrosine luminescence in vitro using gastric tissue samples from cancer surgeries, specifically including tumor tissue, resection margins, and regional lymph nodes. Kinetic data were directly compared with corresponding histology results. Each sample was stained with a 1 mmol/L erythrosine solution and irradiated with ten pulses from a solid-state Ne:AlYG laser at 532 nm. Results indicate that kinetic curve characteristics depend heavily on tissue molecular oxygen levels and the rate constants of oxygen-dependent processes during laser excitation. Specifically, these include the rates of formation and consumption of singlet oxygen, alongside molecular oxygen diffusion from the atmosphere. Notably, pulse-periodic excitation revealed reversible quenching of delayed fluorescence intensity following the annihilation of triplet-excited erythrosine and singlet oxygen in tumor tissues. This quenching is attributed to tumor tissues exhibiting, when compared to normal tissues: (a) lower molecular oxygen content due to hypoxia and anaerobic glycolysis; (b) higher singlet oxygen chemical binding rates, presumably with radicals, membrane lipids, and proteins; and (c) reduced molecular oxygen diffusion caused by a dense extracellular matrix. Collectively, these factors create a temporary oxygen deficit, significantly altering the decay kinetics of the erythrosine label's long-term luminescence. Such kinetic differences between healthy and tumor tissues may reflect underlying metabolic variations in the samples studied, ultimately providing a reliable foundation for the rapid intraoperative determination of resection margins during surgery.

Speaker

Azamat Ishemgulov
Orenburg State University
Russia

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