3D打印石墨烯三维结构

Adam E. Jakus,Ethan B. Secor,Alexandra L. Rutz,Sumanas W. Jordan,Mark C. Hersam,*and Ramille N. Shah*

† ‡ )

Three-Dimensional Printing ofHigh-Content Graphene Scaff olds for ElectronicandBiomedicalApplications †,• † ‡,• ^ ,†,

^ ,†,•,^ Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, United States, Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, §United States, Simpson Querrey Institute for BioNanotechnology, Northwestern University, 303 East Superior Street, Chicago, Illinois 60611, United States, Department of Surgery, Northwestern

University, 251 East Huron Street,

Galter 3-150, Illinois 60611, United States, andDepartment of Chemistry, Northwestern University, 2220 Campus Drive, Evanston Illinois 60208, United States

ABSTRACT The exceptional properties of graphene enable

applications in electronics, optoelectronics, energy storage, and

structural composites. Here we demonstrate a 3D printable

graphene (3DG) composite consisting of majority graphene and

minority polylactide-co-glycolide, a biocompatible elastomer, 3D-

printed from a liquid ink. This ink can be utilized under ambient

conditions via extrusion-based 3D printing to create graphene structures with features as small as

100 μm composed of as few as two layers (10 cm thick object). The resulting 3DG material is mechanically robust and flexible while retaining electrical conductivities greater than 800 S/m, an order of magnitude increase over previously reported 3D-printed carbon materials. In vitro experiments in simple growth medium, in the absence of neurogenic stimuli, reveal that 3DG supports human mesenchymal stem cell (hMSC) adhesion, viability, proliferation, and neurogenic differentiation with significant upregulation of glial and neuronal genes. This coincides with hMSCs adopting highly elongated morphologies with features similar to axons and presynaptic terminals. In vivo experiments indicate that 3DG has promising biocompatibility over the course of at least 30 days. Surgical tests using a human cadaver nerve model also illustrate that 3DG has exceptional handling characteristics and can be intraoperatively manipulated and applied to fine surgical procedures. With this unique set of properties, combined with ease of fabrication, 3DG could be applied toward the design and fabrication of a wide range of functional electronic, biological, and bioelectronic medical and nonmedical devices.

KEYWORDS: graphene . 3D printing . tissue engineering . neurogenesis )

G raphene has been the focus of

significant interest in both

academic

settings.

4 1 2 and industrial 3 With exceptional electronic, mechanical, and thermal properties, it is widely hailed for a

range of applications from high-speed

electronics and energy storage devices to

electrochemical sensors. 7,8 5 6 More recently,

9,10 it has been used as a new biocom- patible, conductive biomaterial for drug 11 12 delivery, stem cell differentiation, 13 14 biosensors, imaging, and osteo, cardiac,

and neuro tissue engineering and 1518 regeneration. The direct manipulation

of graphene, on micro- and macroscopic

scales, is desirable for many of these

applications. In this regard, digital,

additive, and solutionphase printing

technologies offer a promising approach.

For example, inkjet and gravure printing of

graphene have been de- transistors, supercapacitors, transparent 7,1924 conductors, and interconnects. While significant and having many applications, demonstrations to date remain limited to thin film, paper, or hydrogel composite 7,11,2327 formats. Here we extend the fabrication of graphene structures to the third dimension using three-dimensional (3D) printing to greatly expand the versatility and functionality of this material for emerging electronic and biomedical applications. 3D printing is widely considered a revolutionary manufacturing technology, with significant promise in a broad range of fields including tissue and organ engineering. Direct ink writing is an extrusion-based 3D printing technique involving the deposition of a liquid material ink that rapidly solidifies upon extrusion and allows the fabrication of 3D objects layer-by-layer. Direct ink writ- * Address correspondence to [email protected], [email protected]. Received for review February 20, 2015 and accepted April 10, 2015. Published online April 10, 2015 10.1021/acsnano.5b01179 C

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JAKUS ET AL. V OL. 9 ’ NO. 4 ’ 4636–4648 ’