ECG of cardiomyocytes
New sensors monitor the electrical activity of heart cells without damaging them
Tatiana Matveeva, "Scientific Russia"
Engineers from the University of California, San Diego (USA) have developed a new tool that tracks electrical activity inside heart cells using tiny sensors that penetrate cells without damaging them. The device directly measures the movement and speed of electrical signals passing inside one heart cell and between several heart cells – including in 3D-printed tissues, the press service of the university reports. A description of the development appeared in the journal Nature Nanotechnology. (Wang et al., Three-dimensional transistor arrays for intra- and inter-cellular recording).
The new sensor allows you to make very high-resolution images that show what is happening in the heart: which cells are malfunctioning, which parts are out of sync with others. Using such "maps", researchers can determine where the electrical signal passes weakly.
The device consists of a three-dimensional array of microscopic field-effect transistors, which have the shape of pointed tips. These tiny field-effect transistors penetrate cell membranes without damaging them. They are sensitive enough to detect electrical signals – even very weak ones – directly inside cells. Field-effect transistors can simultaneously monitor signals from several cells and even from different parts of the same cell. So that the sensors can stay inside the cells for a long time, they are covered with a phospholipid double layer.
Creating the device, the team first manufactured field-effect transistors in the form of two-dimensional shapes, and then attached individual points of these shapes to a pre-stretched sheet of elastomer. Then the scientists loosened the elastomer sheet – and the device bent, and the field-effect transistors folded into a three-dimensional structure so that they could penetrate into the cells. It's like a book with three-dimensional pictures: when we open it, the panorama pictures grow vertically. So is the new device: at first it is a flat sheet, and under the action of compressive force it becomes voluminous – the tips "pop out" in some areas.
The team tested the device on cultures of heart muscle cells and on heart tissues grown in the laboratory. The scientists placed the samples at the top of the device, and then monitored the electrical signals that were picked up by the sensors of the field-effect transistors. By seeing which sensors detected the signal first and measuring the time it took for other sensors to catch the signal, the team was able to determine the direction of the signals and their speed – both for those that move between neighboring cells, and – for the first time – for those that move inside one heart muscle cell.
The scientists also noticed that signals inside individual heart cells pass almost five times faster than signals between several cells.
The device can help to get more detailed information about heart diseases, such as arrhythmia (heart rhythm disturbance), heart attack and cardiac fibrosis (thickening or thickening of the heart tissue).
Portal "Eternal youth" http://vechnayamolodost.ru