Free-form co-axial bioprinting of a gelatin methacryloyl bio-ink by direct in situ photo-crosslinking during extrusion

O’Connell, Cathal; Konate, Salamata; Onofrillo, Carmine; Kapsa, Robert M. I.; Baker, Chris I.; Duchi, Serena; Eekel, Timon; Yue, Zhilian; Beirne, Stephen; Barnsley, Grant; Bella, Claudia Di; Choong, Peter; Wallace, Gordon G.

doi:10.1016/j.bprint.2020.e00087

Cited by 35 publications

(27 citation statements)

References 26 publications

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“…create a stiffness gradient through an opaque photo-crosslinkable gel. 71 This strategy relies on the idea that the rate of photo-cross-linking is proportional to incident light intensity. The high absorption coefficients for a 405 nm light through the GelMA/GO precursor solutions (Figure 1B) suggest that the light intensity may be significantly attenuated via quenching through a 2 mm thick hydrogel.…”

Section: Resultsmentioning

confidence: 99%

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

Mendes

Silva

O’Connell

et al. 2021

ACS Biomater. Sci. Eng.

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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 electroactivity, 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 (∼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 Ω compared with 340 Ω 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 ∼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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Section: Resultsmentioning

confidence: 99%

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

Mendes

Silva

O’Connell

et al. 2021

ACS Biomater. Sci. Eng.

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“…An advancement in the creation of free-standing structures without the need of support materials was made recently by Connell et al who performed in situ rapid photocrosslinking of GelMA bioinks as it is being extruded from the nozzle [ 126 ]. They also demonstrated a co-axial extrusion system, allowing the encapsulation of a soft or liquid core within the rapidly photocrosslinked shell filament.…”

Section: Biofabrication Of Natural Hydrogel-based Scaffoldsmentioning

confidence: 99%

Biofabrication of natural hydrogels for cardiac, neural, and bone Tissue engineering Applications

Elkhoury

Morsink²,

Sánchez-González³

et al. 2021

Bioactive Materials

111

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Natural hydrogels are one of the most promising biomaterials for tissue engineering applications, due to their biocompatibility, biodegradability, and extracellular matrix mimicking ability. To surpass the limitations of conventional fabrication techniques and to recapitulate the complex architecture of native tissue structure, natural hydrogels are being constructed using novel biofabrication strategies, such as textile techniques and three-dimensional bioprinting. These innovative techniques play an enormous role in the development of advanced scaffolds for various tissue engineering applications. The progress, advantages, and shortcomings of the emerging biofabrication techniques are highlighted in this review. Additionally, the novel applications of biofabricated natural hydrogels in cardiac, neural, and bone tissue engineering are discussed as well.

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“…O 'Connell et al, demonstrated rapid crosslinking (less than 1 second) of a coaxial bioink directly following extrusion. At an optimal formulation of GelMA 10%, gelatin 3% and HA 1%, this overcomes printability and gelation issues observed with some pre-and postcrosslinking methods in bioprinting (Connell et al, 2020).…”

Section: Personalised Treatmentmentioning

confidence: 91%

3D scaffolds in the treatment of diabetic foot ulcers: New trends vs conventional approaches

Glover

Stratakos

Váradi

et al. 2021

International Journal of Pharmaceutics

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Free-form co-axial bioprinting of a gelatin methacryloyl bio-ink by direct in situ photo-crosslinking during extrusion

Cited by 35 publications

References 26 publications

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

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

Biofabrication of natural hydrogels for cardiac, neural, and bone Tissue engineering Applications

3D scaffolds in the treatment of diabetic foot ulcers: New trends vs conventional approaches

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