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A new “biomaterial” for diagnostics and tissue implants

A new biomaterial that is elastic, conducts electricity and supports living cells was fabricated at IISc recently. This polymer blend - called dPEDOT - has promising applications in robotics and medicine.
Biomaterials are special: they are used in devices that interact with the human body during diagnostic procedures and surgery. They are also used in tissue implants, as scaffolds on which cells are grown, and as biosensors to detect the presence of specific proteins. Incorporating the conductivity of metals with the ease in materials processing using polymers presents many challenges to researchers looking to increase the versatility of materials in biological applications. Scientists have had to choose between either good electrical conductivity or flexibility, while the perfect combination of both properties has eluded them. 
Namrata Gundiah’s group at the Department of Mechanical Engineering in IISc has achieved this elusive combination by blending a widely used polymer in solar cell applications, PEDOT-PSS, with two chemical additives, glycerol and polyvinyl alcohol. 
The biomaterial was made by thoroughly mixing ingredients in fixed proportions, spreading the mixture into a thin sheet and baking it to obtain a film. The researchers performed experiments on this film, stretching it to study mechanical properties and testing its electrical conductivity at various temperatures. 
The results were impressive. “We managed to make a polymer which is not only mechanically compliant, but also electrically the best…,” says Suchi S Agrawal, one of the authors on the study. The material’s conductivity had shot up seven-fold and its stretchability increased by up to six times as compared to its parent polymer.
But a polymer can be used in proximity with living tissue only after testing for its tolerance towards the material. There should not be an adverse reaction to the polymer if it is used in implants or medical devices placed inside the body. The researchers performed a clinching test to find that animal cells could thrive on the surface of a dPEDOT film while retaining their normal growth and survival ability.
This experiment is an important first step in establishing such biocompatibility, says Agrawal. 
The perfect recipe which makes dPEDOT so special was not discovered by accident, though. Pranav C. Khandelwal, one of the authors, came up with the idea of using specific ingredients to make the final composite. Glycerol gives the polymer its higher conductivity and water-resistance while polyvinyl alcohol makes the material flexible. The authors also found unique chemical interactions and molecular arrangements in their biomaterial when visualized using advanced microscopy.  
Gundiah’s group wants to take their study further by using a dPEDOT-based apparatus to study the response of heart cells to electric impulses. “This is only one small aspect of our study…we have big aims with it,” Agrawal says. 
But the researchers are clearly excited; dPEDOT appears to be a material with many possibilities.
About the authors
Namrata Gundiah is an Assistant Professor at the Department of Mechanical Engineering, IISc. Suchi Agrawal works in her lab. Pranav Khandelwal carried out all the reported work in her lab when affiliated as a Masters student at Indian Institute of Science Education and Research, Thiruvananthapuram. Manoj A. G. Namboothiry is an Assistant Professor at the Department of Physics in the Indian Institute of Science Education and Research, Thiruvananthapuram. 
Journal information: Journal of Materials Chemistry B is an international journal published by the Royal Society of Chemistry.