3.8 Article

Enhanced Electroactivity, Mechanical Properties, and Printability through the Addition of Graphene Oxide to Photo-Cross-linkable Gelatin Methacryloyl Hydrogel

期刊

ACS BIOMATERIALS SCIENCE & ENGINEERING
卷 7, 期 6, 页码 2279-2295

出版社

AMER CHEMICAL SOC
DOI: 10.1021/acsbiomaterials.0c01734

关键词

GelMA; graphene oxide; soft electroactive hydrogel; soft conductive hydrogel; 3D printing

资金

  1. ARC Centre of Excellence for Electromaterials Science (ACES)
  2. Aikenhead Centre for Medical Discovery -St Vincent's Hospital

向作者/读者索取更多资源

The challenge of creating soft and electroactive materials to interface with sensitive human tissues has been addressed by developing biocompatible photo-cross-linkable soft hybrid electroactive hydrogels based on GelMA and graphene oxide. These materials show significantly enhanced electroactivity while retaining desired mechanical properties, making them suitable for a wide range of applications in bioelectronics, tissue engineering, and drug delivery.
The human tissues most sensitive to electrical activity such as neural and muscle tissues are relatively soft, and yet traditional conductive materials used to interface with them are typically stiffer by many orders of magnitude. Overcoming this mismatch, by creating both very soft and electroactive materials, is a major challenge in bioelectronics and biomaterials science. One strategy is to imbue soft materials, such as hydrogels, with electroactive properties by adding small amounts of highly conductive nanomaterials. However, electroactive hydrogels reported to date have required relatively large volume fractions (>1%) of added nanomaterial, have shown only modest electro-activity, and have not been processable via additive manufacturing to create 3D architectures. Here, we describe the development and characterization of improved biocompatible photo-cross-linkable soft hybrid electroactive hydrogels based on gelatin methacryloyol (GelMA) and large area graphene oxide (GO) flakes, which resolve each of these three limitations. The addition of very small amounts (less than a 0.07% volume fraction) of GO to a 5% w/v GelMA hydrogel resulted in a dramatic (similar to 35-fold) decrease in the impedance at 1 Hz compared with GelMA alone. The GelMA/GO coated indium tin oxide (ITO) electrode also showed a considerable reduction in the impedance at 1 kHz (down to 170 Omega compared with 340 Omega for the GelMA-coated ITO), while charge injection capacity increased more than 6-fold. We attribute this enhanced electroactivity to the increased electroactive surface area contributed by the GO. Despite this dramatic change in electroactivity, the GelMA/GO composite hydrogels' mechanical properties were only moderately affected. Mechanical properties increased by similar to 2-fold, and therefore, the hydrogels' desired softness of <4 kPa was retained. Also, we demonstrate how light attenuation through the gel can be used to create a stiffness gradient with the exposed surface of the gel having an elastic modulus of <1.5 kPa. GO addition also enhanced the rheological properties of the GelMA composites, thus facilitating 3D extrusion printing. GelMA/GO enhanced filament formation as well as improved printability and the shape fidelity/integrity of 3D printed structures compared with GelMA alone. Additionally, the GelMA/GO 3D printed structures presented a higher electroactive behavior than nonprinted samples containing the same GelMA/GO amount, which can be attributed to the higher electroactive surface area of 3D printed structures. These findings provide new rational choices of electroactive hydrogel (EAH) compositions with broad potential applications in bioelectronics, tissue engineering, and drug delivery.

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