Optical images of 3D-printed bioceramic scaffold (a) and 4mg/mL polydopamine modified bioceramic scaffold (b) on the top view; scanning electron microscopy (SEM) images of pure bioceramic scaffold (c) and 4mg/mL polydopamine modified bioceramic scaffold with a uniformly self-assembled Ca-P/polydopamine nanolayer surface (d).Repairing bones damaged by cancer surgery requires scaffold materials that are able to support tissue regeneration while suppressing tumor regrowth. Few such scaffold materials have been reported, but now Chinese researchers have come up with a promising approach inspired by the way mussels cling to rocks.
Chengtie Wu at Shanghai Institute of Ceramics, along with coworkers at East China Normal University and Shanghai Jiao Tong University, have created a bioceramic scaffold coated with a self-assembled Ca-P/polydopamine surface layer that can both kill tumor cells and support bone regrowth [Ma et al., Biomaterials 111 (2016) 138].
“It remains a significant challenge to achieve a new biomaterial that can kill the bone tumor cells and inhibit tumor regrowth while at the same time possessing the ability to stimulate log-term bone regeneration after surgical intervention,” explains Wu.
The scaffold is fabricated from a bioceramic (Ca7Si2P2O16), which can be printed into three-dimensional shapes. Inspired by the example of mussels, which adhere tightly to any material, the researchers created a nanostructured surface that helps bone cells stick onto the scaffold and proliferate. The Ca-P/polydopamine layer brings surface roughness, affinity to water (or hydrophilicity), and bioactive functional groups (OH- and NH2-), all of which support cell adhesion, proliferation, and differentiation.
The researchers believe that organic chemical groups in the polydopamine known as ‘catechol’ groups could also serve to improve the nucleation and growth of the apatite minerals that make up bone.
But the Ca-P/polydopamine layer has yet another potential benefit. It exhibits a photothermal effect – heating up in response to light stimulation – which can be harnessed to kill tumor cells and inhibit growth. Near-infrared laser irradiation of the Ca-P/polydopamine scaffolds induces a temperature of 92 degrees C in air and 50 degrees C in a wet environment.
“Taking advantage of the photothermal effect of polydopamine, the bifunctional scaffolds could effectively induce tumor cell death in vitro and significantly inhibit tumor growth,” says Wu.
The temperature increase is rapid and controllable, say the researchers, and leads to effective tumor growth inhibition in mice. The only issue that needs improvement, admits Wu, is that the center of the scaffold reaches a higher temperature than the periphery. But he is confident that this shortcoming can be improved upon.
The researchers are now looking for industrial and clinical partners to take the technology toward applications.