Xin Chen, Fudan University, Shanghai, China, Raffaele Mezzenga, ETH Zürich, Switzerland, and colleagues show that under carefully selected experimental conditions graphene nanosheets are able to direct one-dimensional self-assembly of silk fibroin (SF).

Silkworm cocoons were dissolved in water at a pH above 10 to get a solution of silk protein. Sheets of graphene oxide and a drop of hydrazine to reduce the graphene oxide to graphene were added. A new type of hybrid nanocomposites formed after stirring the black suspension for six hours at 70 °C. Atomic force microscopy showed that silk fibers completely coved the graphene sheets.

By simply using a vacuum-assisted filtering process, these colloidal hybrids can be processed into well-structured macroscopic films, which have excellent physical properties combing features from both graphene and silk: The sheets were 100 times more conductive and more than 10 times tougher than pure graphene oxide, and remained flexible.
Human cervical cancer cells were grown on the sheets to test the material’s biocompatibility. The cells grew to cover an area on the new material five times larger than on pure graphene.

Due to the facile fabrication process and their tunable nanostructures, these hybrids show promise in applications as diverse as tissue engineering, drug delivery, nanoelectronics, nanomedicine, biosensors, and functional composites.

• Directed Growth of Silk Nanofibrils on Graphene and Their Hybrid Nanocomposites,
  Shengjie Ling, Chaoxu Li, Jozef Adamcik, Suhang Wang, Zhengzhong Shao, Xin Chen, Raffaele Mezzenga,
  ACS Macro Lett. 2014, 3, 146–152.
  DOI: 10.1021/mz400639y