Professor Yoonkey Nam’s research team from the Department of Bio and Brain Engineering has developed a technology that uses inkjet printing to create thermo-plasmonic interfaces capable of modulating neuron activity. The fusion of the inkjet printing and nanoparticle technologies allows for selective nano-photothermic stimulation of neurons and has potential to introduce a new type of therapy for neural diseases such as epilepsy. This work was published in the February issue of ACS Nano under the title “Inkjet-Printed Biofunctional Thermo-Plasmonic Interfaces for Patterned Neuromodulation”, with PhD student Hongki Kang as the first author.
Thermo-plasmonic nanoparticles, metal nanoparticles that generate heat in response to absorption of light at a specific wavelength, have been gaining attention for their potential application in modulating brain activity. Professor Nam’s team had previously discovered that the photothermal effect of these nanoparticles could induce neural inhibition and has been researching methods to use this phenomenon to control the unusual neural activities observed in brain diseases.
Previous research in inkjet printing thermo-plasmonic interfaces entailed many limitations in spatial selectivity and resolution due to the insufficient development of the technologies behind nanoparticle inks and substrate surface printing. The team proposed the use of biocompatible polyelectrolyte layer-by-layer (LbL) coating as a solution to the existing problems with resolution. LbL coating is advantageous in that it can turn any non-printable substrate into a printable one and exhibits exceptional pattern fidelity through nanoparticle pinning. The nanoparticles in the ink are fixed in their assigned positions by their electrostatic interactions with the substrate surfaces. With these advantages, the team was able to create biocompatible interfaces with precisely micro-patterned thermo-plasmonic heat waves and proved that they could very finely control the intensity and effect range of the thermo-plasmonic effect.
The heat waves created this way can be used to selectively modulate neuronal activity: when the inkjet-patterned nanoparticles are exposed to near-infrared (NIR) light, they emit heat in the same pattern that suppresses the activity of only the neurons in the network exposed to the heat. Such selective suppression of desired cells will be useful in providing brain disease patients with customized photothermic neural stimulation therapy. The new technology is also applicable to thin and flexible surfaces, opening up new possibilities for implanted brain devices and wearable medical devices.
Professor Nam commented, “This technology can be used widely in several fields of engineering because it can easily print the desired pattern of heat anywhere.” He added, “In bioengineering, it can be applied to various interfaces that use light and heat to control biological functions and could also be used in new anti-counterfeiting technology.”