Evaluating 3D printed Gelatin-Hydroxyapatite-Reduced Graphene Oxide Nanocomposites

As bone regeneration continues to be a source of enormous potential—and challenge—in tissue engineering, scientists around the world are experimenting with a wide range of techniques and materials. In ‘Physical evaluation of 3D printed gelatin-hydroxyapatite-reduced graphene oxide nanocomposites as a bone tissue engineering scaffold,’ international researchers continue to work on improving biocompatible structures—ultimately for better sustainability of cells.

Due to the biocompatibility of graphene, it has been used in many applications for medicine in recent years, like drug delivery, orthopedics, and bioimaging. Growing in increasing popularity for use with bone replacement, graphene has also been used with hydroxyapatite (HA) and implants. In combining the two materials, HA becomes stronger.

HA and graphene have both also been used to reinforce gelatin, enhancing mechanical and biological properties and ultimately, producing a material with superior printability, allowing users to fabricate complex geometries using both HA and graphene sheets.

For this study, sample gels were prepared for 3D printing, with the following scaffolds being created:

• Pure gelatin
• Gelatin-HA
• Gelatin-HA-rGO

“The hydrogels were put in an oven (65 ^oC) and stirred for 12 h. The working bed temperature was -10 ^oC and the heating barrel fixed to the 3D printer was set to 40 ^oC. A 200 μm needle tip moving at a speed of 30 mm s^-1 was used to extrude the hydrogels. The solution blend was laid by varying the air pressures. The printed scaffolds subsequently were put in a freeze dryer (- 60 ^oC) for 72 h [35]. The scaffolds were printed in 3 cm x 3 cm dimensions and circled using a punch,” stated the researchers.

Graphene sheets were interconnected, forming a 3D structure, with graphene peaks covered by HA peaks. Following samples were a pure gelatin scaffold, gelatin molecule structure, and a pure gelatin scaffold image. Pores were spherical and measured under 30 micrometers. Other samples consisted of structures with closed porosities, one type measuring 300 micrometers, and the other at 30 micrometers.

The gelatin-HA scaffold showed non-spherical pores that were stretched due to HA particles. Bubbles were visible, with diameters of 200 micrometers.

“HA particles enhance the accuracy of the designed pores. The HA particles are likely to influence the rheology of the gels, and with the stability of all 3D printer factors, the scaffold structure’s accuracy is improved,” stated the researchers.

In the gelatin-HA-rGO scaffold, pores were smaller than previous samples, and also spherical. The gel was ‘altered’ due to the composition of the graphene sheets, leading to spherical porosities. Further as HA, rGO, and gelatin were combined, the researchers noted that the agents left over were bound to the gelatin, leaving HA and graphene ‘coherent.’ This resulted overall in a ‘three-way interconnection’ between the phases, with improved mechanical properties.

Last, the researchers noted cracking caused by the bending of scaffolds.

“As a result of the bending of the scaffolds, the cracks created in the gelatin-HA scaffold grow in a way that the resulting cracks are smaller than the cracks created in the pure gelatin scaffold and are moved to the corner of the scaffold. These changes in the shape of the cracks are also noticeable in the case of the gelatin-HA-rGO scaffold, which the crack is smaller and more inclined toward the corner than other scaffolds,” concluded the researchers.”These findings indicate that the presence of graphene and HA increased the bending resistance of the scaffolds.

“The findings of this study showed that the addition of graphene and HA to gelatin changed the rheology, reduced the size of pores, and increased the accuracy of the designed pores. The addition of HA and graphene also increased the bending strength and changed the shape of the resulting cracks. The findings of this study will be useful for the design of tissue engineering scaffolds.”

Scaffolds are and will inevitably continue to be a source of research as scientists consider different types of structures and materials, and techniques. What do you think of this news? Let us know your thoughts; join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

[Source / Images: ‘Physical evaluation of 3D printed gelatin-hydroxyapatite-reduced graphene oxide nanocomposites as a bone tissue engineering scaffold’]