Inkjet printing multilayered reflectins thin films for bioelectronics

Proteins called reflectins, located in the reflective and iridescent skin cells of squid and other cephalopods, have garnered interest in the development of proton-conductive components for biocompatible electronics.

Reflectins have relatively high bulk proton conductivities and carrier mobilities, which hold potential for a wide range of applications, such as protonic transistors for next-generation biological sensing. They also support the growth of neural stem cells, making them useful in research on neurological diseases and brain injuries.

The general method for processing the proteins into thin films for electrical performance evaluation has been drop casting, i.e., mixing the proteins in a solvent, then spreading the solution onto substrates, where a solid film would form as the solution evaporates. The process is labor intensive, inefficient, and often require organic solvents.

Lu et al. sought to improve the process by incorporating inkjet printing in their approach, and used water as the solvent to fabricate layers of reflectin. The researchers tested two of the resulting reflectin thin films using both gold and palladium electrodes.

They used electrochemical impedance spectroscopy to measure the electrical properties of the proteins in the presence of water and deuterium oxide. They compared their results with those published on reflectins made using drop casting and found good agreement between the results.

“Our methodology constitutes a promising step forward for the manufacturing and continued improvement of advanced bioelectronic platforms from the reflectin class of proteins,” said author Alon Gorodetsky.

Source: “Proton conduction in inkjet-printed reflectin films,” by Yujia Lu, Preeta Pratakshya, Atrouli Chatterjee, Xiaoteng Jia, David D. Ordinario, Long Phan, Juana A. Cerna Sanchez, Rylan Kautz, Vivek Tyagi, Priyam Patel, Yegor Van Dyke, MyAnh K. Dao, Justin Couvrette, Justin P. Kerr, James Long, Alex Allevato, Jessica Leal-Cruz, Eric Tseng, Ethan R. Peng, Andrew Reuter, Samantha Drake, Fiorenzo Omenetto, and Alon A. Gorodetsky, APL Materials (2020). The article can be accessed at https://doi.org/10.1063/5.0019552 .