Conductive Graphene/Noble Metal Nanoparticle/Silk-PMMA Composite Thin Film Biomaterials

Evan K. Lee, Sophie R. Cohen, Thomas A. Alvermann, Jenny L. Wang, R. Kenneth Sims, Alexander N. Mitropoulos, Enoch A. Nagelli

Department of Chemistry & Life Science, Chemical Engineering Program, United States Military Academy, West Point, New York 10996

Abstract

Conductive biomaterials offer immense utility in biosensor, biomedical device, and energy storage applications. Biopolymers are limited by low conductivity, type of materials, and mechanical integrity. Moreover, current methods to develop conductive biomaterials involve the need for external stimuli sources and the use of harsh reducing agents. The superior properties of graphene make it ideal for enhancing electrical, thermal, chemical, and mechanical stability for noble metal nanoparticle-based biopolymers. Here we utilize spontaneous galvanic displacement driven by reduction potential difference to produce graphene-biopolymer-noble metal nanoparticle hybrid nanocomposites without the use of any chemical reducing agents. Copper supported graphene-silk thin films are immersed into aqueous noble metal salt solutions (HAuCl₄, K₂PtCl₄, and Na₂PdCl₄) to enable electroless noble metal nanoparticle deposition onto graphene-silk thin films through the galvanic displacement of copper. The resulting graphene/silk/noble metal nanoparticle thin films on copper are then encapsulated by poly(methyl methacrylate) (PMMA) before sacrificially etching the supporting copper substrate away to form free-standing conductive biomaterial films. We demonstrate the usage of reduction potential as the driving force for producing conductive silk fibroin makes the process a more simple, scalable, and cost-efficient alternative to current methods for developing conductive free-standing biomaterials, which necessitate the use of external stimuli and harsh reducing agents.

KEYWORDS: Graphene, Noble Metal Nanoparticles, Silk, Biomaterials, Thin Films

CONTACT: Dr. Enoch Nagelli, Department of Chemistry and Life Science, United States Military Academy, West Point, New York 10996. Email: enoch.nagelli@westpoint.edu