Researchers at McKelvey School of Engineering at Washington University in St. Louis are presently using nanoparticles as heaters to control the neurons' electrical activity in the brain and of cardiomyocytes in the heart.
A ScienceDaily report specified that nanomaterials had been used in various emerging applications, such as in targeted pharmaceuticals, or to strengthen other materials and products such as sensors and energy that harvest and storage devices.
The findings of the study have the potential to be translated to other types of excitable cells and function as a valuable tool in nano-neuroengineering.
According to materials scientist Srikanth Singamaneni and biomedical engineer Barani Raman, their teams collaborated to develop a noninvasive technology that hinders the electrical activity of neurons through PDA or polydopamine nanoparticles and near-infrared light.
PDA Nanoparticles
Essentially, the negatively charged PDA nanoparticles, which are selectively binding to neurons, absorb near-infrared light that generates heat, which is then transmitted to the neurons, hindering their electrical activity.
Singamaneni, the Lilyan & E. Lisle Hughes Professor in the Department of Mechanical Engineering & Materials Science said, they showed they could inhibit these neurons' activity and prohibit their firing, not just on and off, although in a graded way.
By controlling the light intensity, the materials scientists added can control the neurons' electrical activity. Once the light was stopped, they can completely bring them back again minus any impairment.
On top of their ability to effectively transform light into heat, this study indicated that the PDA nanoparticles are both quite biodegradable and biocompatible.
The nanoparticles are ultimately degrading, making them a convenient tool for employment in both vitro and in vivo experiments in the future.
The 'Coffee' Analogy
Singamaneni explained that when one pours cream into hot coffee, it dissolves and becomes creamed coffee through a diffusion process.
In addition, it is similar to the process that's controlling which ions are flowing in and out of the neurons. Diffusion relies on temperature; thus, if one has a good handle on the heat, he controls the diffusion rate close to the neurons.
This would, in turn, affect the cell's electrical activity. The study, Reversible Photothermal Modulation of Electrical Activity of Excitable Cells using Polydopamine Nanoparticles, published in Advanced Materials, demonstrates the concept that the photothermal effect, converting light into heat, is close to the vicinity of nanoparticles tagged neurons can be applied as a method to remotely control specific neurons.
For their coffee analogy to continue, the team has designed a photothermal foam that's similar to a sugar cube, forming a density of population of nanoparticles in tight packaging, acting faster than individual sugar crystals dispersing, explained Raman.
He also said, with so many of the nanoparticles packed in a small volume, the foam is faster in transducing light to heat and gives more effective control to only neurons wanted.
Photothermal Process
A similar Phys.org report said One does not have to use high-intensity power to produce the same impact. Additionally, the team, which includes biomedical engineering associate professor Jon Silva applied the PDA nanoparticles to heart muscle cells or cardiomyocytes.
Intriguingly, the photothermal process excited the cardiomyocytes, showing that such a process can raise or lessen the excitability in cells that depend on their type.
According to Raman, the excitability of a tissue or cell, be it cardiomyocytes or muscle cells, relies to a certain extent on diffusion.
More so, while cardiomyocytes comprise various rules set, the principle that regulates the sensitivity to temperature can be anticipated to be the same.
Now, the team is examining how different neuron types are responding to the stimulation process. They will be aiming for particular neurons by selectively binding the nanoparticles for the more selective regulator to be provided.
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