Triggering Neurotransmitters Secretion from Single Cells by X-ray Nanobeam Irradiation

Abstract

The employment of ionizing radiation is a powerful tool in cancer therapy, but beyond targeted effects, many studies have highlighted the relevance of its off-target consequences. An exhaustive understanding of the mechanisms underlying these effects is still missing, and no real-time data about signals released by cells during irradiation are presently available. We employed a synchrotron X-ray nanobeam to perform the first real-time simultaneous measurement of both X-ray irradiation and in vitro neurotransmitter release from individual adrenal phaeochromocytoma (PC12) cells plated over a diamond-based multielectrode array. We have demonstrated that, in specific conditions, X-rays can alter cell activity by promoting dopamine exocytosis, and such an effect is potentially very attractive for a more effective treatment of tumors.

Advanced real-time recordings of neuronal activity with tailored patch pipettes, diamond multi-electrode arrays and electrochromic voltage-sensitive dyes

“…The micrographitized diamond MEA (16 channels), when used as amperometric sensors, have been employed to detect quantal release events not only from neuroendocrine chromaffin and PC12 cells [83], whose oxidation of granule content produces current events of hundreds of picoamperes and lasting tens of milliseconds, but also from cultured midbrain dopaminergic neurons: in this case, spike duration is completed within hundreds of microseconds [109]. Monitoring quantal exocytosis from dopaminergic neurons requires to increase the sampling frequency from 4 to > 25 kHz [109].…”

XMEA: A New Hybrid Diamond Multielectrode Array for the In Situ Assessment of the Radiation Dose Enhancement by Nanoparticles

“…A diamond multielectrode array (MEA) device was originally designed to study the chemical products of exocytotic events from cells [ 40 ], but its unique architecture, combining the diamond electrodes to a cell-culture well, would also potentially allow the quantification of the radiation dose to the cell cultures, given the radiation sensitivity of the electrode material [ 41 ].…”

An Ultramicroelectrode Electrochemistry and Surface Plasmon Resonance Coupling Method for Cell Exocytosis Study

“…UME electrochemistry is the most commonly used method to study electroactive substances released during exocytosis, such as neurotransmitters. − The electrodes, with diameters ranging from micrometers to nanometers, are positioned near or inserted into the cell by using microscopic devices. The electroactive substances react on the electrode surface, generating redox peaks or current spikes, allowing for the determination of kinetics, chemical information, and substance concentrations released during exocytosis. ,, Among the existing ultramicroelectrodes, the carbon nanopipette (CNP) electrode has a cavity geometry similar to a microcollection bottle, which can reduce the diffusion loss of released neurotransmitters. − In addition, CNP electrodes are easy to prepare and modify and have an adjustable electroactive area. Therefore, they have been widely used in exocytosis studies. ,− While those methods provide a tremendous amount of valuable information about single cell and individual event, it is not enough to obtain only single-cell exocytosis information in many cases, just like in the pharmaceutical industry, in which it is necessary to test the response of candidate drugs to cell cultures and even organisms, rather than just evaluating their impact on a single target molecule .…”