Nanoparticles create heat from light to manipulate electrical activity in neurons | Source

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Nanomaterials have been used in a variety of emerging applications, such as in targeted pharmaceuticals or to enhance other materials and products such as sensors and devices for energy recovery and storage. A team from the McKelvey School of Engineering at Washington University in St. Louis is using nanoparticles as heating elements to manipulate the electrical activity of brain neurons and heart cardiomyocytes.

The results, published on July 3, 2021, in Advanced materials, have the potential to be translated into other excitable cell types and to serve as a valuable tool in nano-neuroengineering.

Singamaneni (Photo: Ron Klein)

Srikanth Singamaneni, a materials scientist, and Barani Raman, a biomedical engineer, and their teams collaborated to develop a non-invasive technology that inhibits the electrical activity of neurons using polydopamine (PDA) nanoparticles and near light infrared. Negatively charged PDA nanoparticles, which selectively bind to neurons, absorb near infrared light which creates heat, which is then transferred to neurons, inhibiting their electrical activity.

“We have shown that we can inhibit the activity of these neurons and stop their activation, not only on and off, but gradually,” said Singamaneni, Professor Lilyan & E. Lisle Hughes in the Department of Mechanical Engineering and Science of materials. “By controlling the light intensity, we can control the electrical activity of neurons. Once we turn off the light, we can bring them back completely without any damage. “

In addition to their ability to efficiently convert light into heat, PDA nanoparticles are highly biocompatible and biodegradable. Nanoparticles eventually degrade, making them a handy tool to use in in vitro and in vivo experiences in the future.

Raman

Raman, professor of biomedical engineering, likens the process to adding cream to a cup of coffee.

“When you pour cream into hot coffee, it dissolves and becomes creamy coffee by the diffusion process,” he explained. “It’s similar to the process that controls which ions go in and out of neurons. Diffusion is temperature dependent, so if you control heat well, you control the rate of diffusion near neurons. This in turn would have an impact on the electrical activity of the cell. This study demonstrates the concept that the photothermal effect, converting light into heat, near neurons labeled with nanoparticles can be used as a way to remotely control specific neurons.

To continue the coffee analogy, the team designed a photothermal foam similar to a lump of sugar, forming a dense population of nanoparticles in a sealed package that act faster than individual sugar crystals that disperse, said Raman.

“With so many of them packaged in a small volume, the foam more quickly transduces light into heat and gives more effective control only to the neurons we want,” he said. “You don’t have to use high intensity power to generate the same effect. ”

Additionally, the team, which includes Jon Silva, associate professor of biomedical engineering, applied PDA nanoparticles to cardiomyocytes, or heart muscle cells. Interestingly, the photothermal process excited cardiomyocytes, showing that the process can increase or decrease the excitability of cells depending on their type.

“The excitability of a cell or a tissue, whether it is cardiomyocytes or muscle cells, depends to some extent on diffusion,” Raman said. “While cardiomyocytes have a different set of rules, the principle that controls temperature sensitivity may be similar.”

Now the team is examining how different types of neurons respond to the stimulation process. They will target particular neurons by selectively binding the nanoparticles to provide more selective control.


The McKelvey School of Engineering at Washington University in St. Louis promotes independent research and education with an emphasis on scientific excellence, innovation and collaboration without borders. McKelvey Engineering offers leading research and graduate programs across all departments, particularly in Biomedical Engineering, Environmental Engineering, and Computer Science, and has one of the most selective undergraduate programs in the world. country. With 140 full-time faculty, 1,387 undergraduates, 1,448 graduate students and 21,000 alumni alive, we work to solve some of society’s greatest challenges; prepare students to become leaders and innovate throughout their careers; and be a catalyst for economic development for the Saint-Louis region and beyond.

This project was supported by the Air Force Office of Scientific Research (# FA95501910394) and the National Institutes of Health (R01-HL136553).


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