Kanazawa University research

A biosensor for measuring extracellular hydrogen peroxide concentrations

KANAZAWA, Japan, Feb. 26, 2021 /PRNewswire/ -- Researchers at Kanazawa University report in Biosensors and Bioelectronics a successful test of a sensor for measuring hydrogen peroxide concentrations near cell membranes.  The sensor has the potential to become a tool for new cancer therapies.

Several processes in the human body are regulated by biochemical reactions involving hydrogen peroxide (H₂O₂). Although it can act as a 'secondary messenger', relaying or amplifying certain signals between cells, H₂O₂ is generally toxic because of its oxidant character. The latter means that it converts (oxidizes) biochemical molecules like proteins and DNA. The oxidizing property of H₂O₂ is of potential therapeutic relevance for cancer, though: deliberately causing tumor cells to increase their H₂O₂ concentration would be a way to destroy them. In light of this, but also for monitoring pathologies associated with H₂O₂ overproduction, it is crucial to have a means to reliably quantify hydrogen peroxide concentrations in the extracellular environment. Now, Leonardo Puppulin from Nano Life Science Institute (WPI-NanoLSI), Kanazawa University and colleagues have developed a sensor for measuring concentrations of H₂O₂ in the vicinity of cell membranes, with nanometer-resolution.

The biosensor consists of a gold nanoparticle with organic molecules attached to it. The whole cluster is designed so that it anchors easily to the outside of a cell's membrane, which is exactly where the hydrogen peroxide molecules to be detected are. As attachment molecules, the scientists used a compound called 4MPBE, known to have a strong Raman scattering response: when irradiated by a laser, the molecules consume some of the laser light's energy. By measuring the frequency change of the laser light, and plotting the signal strength as a function of this change, a unique spectrum is obtained — a signature of the 4MPBE molecules. When a 4MPBE molecule reacts with a H₂O₂ molecule, its Raman spectrum changes. Based on this principle, by comparing Raman spectra, Puppulin and colleagues were able to obtain an estimate of the H₂O₂ concentration near the biosensor.