(93d) "Fabrication of Micropatterned Flexible Biofunctional Devices Based on Silk Proteins"

Polymers from nature provide exciting possibilities as biomimetic materials for the development of mechanically deformable and biodegradable systems. In particular, biopolymers from the silkworm - fibroin and sericin, are being extensively explored due to exceptional mechanical and optical properties, along with biocompatibility and degradability. Our group reported on a technique that permits the use of photolithography via photoreactive conjugates of silk proteins that behave like negative tone photoresists.¹ High resolution protein features can be precisely patterned at sub-microscale resolution (µm) at the bench-top over macroscale areas (cm), easily and repeatedly with high-throughput. This fabrication strategy using proteins can be used for application areas ranging from tissue engineering to bioelectronics, photonics, and drug delivery. We show how periodic, microstructured arrays can be patterned on flexible films to form structurally induced iridescent and functional, soft optical structures.² To demonstrate the broader applicability of silk protein lithography, we present the formation of a fully organic, biodegradable and flexible bioelectronic device. The conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with photo-sericin is used to form a photoreactive, aqueous-conductive ink. Conducting micropatterns are then formed on a flexible silk fibroin sheet using photolithography. We show how this flexible and conformable organic device can be used to sense electroactive biomolecules such as dopamine and ascorbic acid, or to encapsulate enzymes such as glucose oxidase for the specific detection of glucose.³ The silk-based micropatternable functional composites are formed using all water based green fabrication approach and shown to be cell friendly and degradable. Such systems can find applications in implantable optical devices, in-vivo bio-sensors, and bio-optoelectronic devices.

References:

1. "Precise patterning of silk microstructures using photolithography" - NE Kurland, Tuli Dey, SC Kundu, VK Yadavalli, Advanced Materials, 25(43), 6207-6212, 2013.

2. "Biopatterning of silk proteins for soft micro-optics" - RK Pal, NE Kurland, C Wang, SC Kundu, VK Yadavalli, ACS Applied Materials & Interfaces, 7(16), pp 8809â??8816, 2015

3. "Conducting polymer-silk biocomposites for flexible and biodegradable electrochemical sensors" - RK Pal, AA Farghaly, MM Collinson, SC Kundu, VK Yadavalli, Biosensors & Bioelectronics, 2016, in press