(729d) Electroactive Silk Biomimetic Composites As Flexible Electrochemical Sensors

Biomimetic composites of naturally derived and synthetic polymers provide exciting opportunities to develop soft and flexible, physiologically compliant bioelectronics systems. We show that the combination of naturally derived silk proteins and the conducting polymer poly(3,4-ethylenedioxythiophene) :poly(styrene sulfonate) (PEDOT:PSS) enables the formation of functional bioinks for sensing and other electrochemical applications. The inks combine the mechanical strength, biocompatibility and degradability of silk proteins, with the conductivity and chemical functionalization of the PEDOT:PSS. Our group earlier demonstrated the fabrication and characterization of photopatternable, water-based conductive inks comprising PEDOT:PSS and synthesized photoreactive silk proteins. [1] The presence of photoreactive groups permits a fully aqueous photolithographic strategy to form conductive micropatterns on both rigid substrates as well as flexible silk films.

In this presentation, we discuss how the composite ink can function for flexible electronics applications in the form of electrodes and electroactive coating materials for conventional rigid electrodes to enhance their electrochemical performance. Investigations with the biomimetic conductive ink have led to the development of biosensing systems in multiple formats without the use of other charge collector support materials. [2, 3] We show how electroactive biomolecules such as neurotransmitters can be detected sensitively, while non-electroactive biomolecules such as glucose and glutamic acid, can be detected by encapsulating specific enzymes. The electroactivity of conductive ink can be improved by the addition of small amounts of reduced graphene oxide (rGO) dopant to obtain highly sensitive detection. Using these doped composites, we further demonstrate flexible energy storage devices due to the capacitive nature of the biomaterial. The presence of silk proteins as the matrix of the composite makes it completely biodegradable and biocompatible, potentially resulting in implantable devices. The mechanical, biochemical and electrochemical characterization of the composite and its microfabrication are discussed. By virtue of a range of versatile properties, utility as bio-sensors, opto-electronic devices and flexible energy storage systems are envisioned.

References:

[1] "Photolithographic micropatterning of conducting polymers on flexible silk matrices" - RK Pal, AA Farghaly, MM Collinson, SC Kundu, VK Yadavalli, Advanced Materials, 28(7), 1406-1412, 2016

[2] “Biosensing using photolithographically micropatterned electrodes of PEDOT:PSS on ITO substrates”- RK Pal, SC Kundu, VK Yadavalli Sensors and Actuators B, 242, 140-147, 2017

[3] "Conducting polymer-silk biocomposites for flexible and biodegradable electrochemical sensors" - RK Pal, AA Farghaly, MM Collinson, SC Kundu, VK Yadavalli, Biosensors & Bioelectronics, 81, 294-302, 2016