(245d) Biomimetic Composites As Microfabricated, Flexible, Degradable Electrochemical Sensors

Biomimetic composites
as microfabricated, flexible, degradable electrochemical sensors

-       
M. Xu, S. Pradhan, R.K. Pal, V.K. Yadavalli

Department of Chemical and Life
Science Engineering, Virginia Commonwealth University, Richmond, VA

Biomimetic composites of
naturally derived and synthetic polymers provide exciting opportunities to
develop mechanically flexible, physiologically compliant, and degradable
bioelectronics systems. In prior work, we have shown that naturally derived
silk proteins and conducting polymers (specifically
poly(3,4-ethylenedioxythiophene) :poly(styrene
sulfonate) (PEDOT:PSS)) can form functional bioinks
for sensing and other electrochemical applications. These inks combine the
mechanical strength, biocompatibility and degradability of silk proteins, with
the conductivity and chemical functionalization of the PEDOT:PSS.
The fabrication and characterization of photopatternable,
water-based conductive inks comprising PEDOT:PSS and
synthesized photoreactive silk proteins was earlier shown [1] The presence of
photoreactive groups permits a fully aqueous photolithographic strategy to form
conductive microelectrodes on both rigid substrates as well as flexible silk
films [2].

Here we will present the latest
developments using this technology, showing how these devices can function for
flexible bioelectronics applications in the form of microelectrodes for
ultrasensitive detection, as well as components such as microsupercapacitors.[3,
4] 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. Due to the
room temperature, aqueous fabrication process, we can immobilize antibodies in
these sensors resulting in flexible immunosensors for targets such as vascular
endothelial growth factor (VEGF) for the first time [3]. The electroactivity of
conductive ink can be improved by the addition of small amounts dopants. 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 transient or implantable devices. This
platform can also be used for the specific control of cell culture in flexible
sheets. 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] "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

[3] “Flexible biosensors for
the impedimetric detection of protein targets using silk-conductive polymer biocomposites” – M Xu, VK Yadavalli,
ACS Sensors, in press, 2019

[4] “Fabrication of Flexible,
Fully Organic, Degradable Energy Storage Devices Using Silk Proteins” - RK Pal,
SC Kundu, VK Yadavalli, ACS Applied Materials
& Interfaces 10 (11), 9620-9628, 2018