Utilisation of Titanium and Titanium Dioxide as Scaffolds for Proliferating Coral Reef

Abstract:

Estimated 30 percent or more of coral reefs are now in danger of extinction by coastal construction increases and global temperatures rise. Several restoration techniques such as fragmentation, forming, Biorock have been developed in the past few years. In vertebrates such as mammals, osteoblast is known to form the bones composed of hydroxyapatite. Therefore, bone substitutional devices are generally surface modified to improve the adhesion of osteoblasts on the surfaces. Titanium dioxide film is often employed as the surface material for hard tissue substitutes made of titanium and its alloys. In hard corals, on the other hand, the soft tissue covered on the skeletons made of calcium carbonate has osteoblasts as well. The purpose of this work was to investigate the potential of titanium (Ti) and titanium dioxide (TiO₂) as scaffolds for proliferating coral reefs by analysing the several interfacial reactions. The rods of pure Ti were anodised in aqueous phosphoric acid at a constant voltage of 80 V. The surfaces were confirmed to be anatase type TiO₂. The coral fragments were kept in contact with the rods in a lab-scale aquarium with artificial seawater for several days. The colony of polyps vigorously expanded on the surfaces. Fragments of coral were placed on pure Ti, TiO₂ coated pure Ti in Petri dishes and were reared in artificial seawater. Fine spherical precipitates of calcium carbonate with aragonite structure, which is the same inorganic substance as corals, were observed radially and regularly on the surfaces of TiO₂. In addition, the adherence of planula larva to the sputtered TiO₂ film was observed by using a QCM (Quartz Crystal Microbalance) method. The approach and adhesion of planula larva to the surface could be detected by monitoring the resonance frequency and resistance. The surfaces might have a great potential in coral reef regenerations.

• Periodical: Materials Science Forum (Volume 1016)
• Pages: 1497-1502
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1016.1497
• Online since: January 2021
• Authors: Masato Ueda*, Chihiro Sawatari, Tomoyuki Takahashi, Hiroaki Tsuruta, Hidenobu Tokushige, Hirohisa Hikosaka, Daigo Yonetsu, Masahiko Ikeda
• Keywords: Bone, Calcium Carbonate, Hard Corals, Planula Larva, Quartz Crystal Microbalance

References

[1] https://wwf.panda.org/our_work/oceans/coasts/coral_reefs/coral_threats.cfm/.

[2] C. Henderson: Electric reefs, New Scientist (2002).

[3] C.A. Boch, A.N.C. Morse, Testing the effectiveness of direct propagation techniques for coral restoration of Acropora spp., Ecological Engineering 40 (2012) 11-17.

DOI: 10.1016/j.ecoleng.2011.12.026

[4] T. Kokubo, F. Miyaji, H. M. Kim, T. Nakamura, Spontaneous formation of bonelike apatite layer on chemically treated titanium metals, J. Am. Ceram. Soc. 79 (1996) 1127–1129.

DOI: 10.1111/j.1151-2916.1996.tb08561.x

[5] X. X. Wang, K. Hayakawa, K. Tsuru, A. Osaka, Bioactive titania gel layers formed by chemical treatment of Ti substrate with a H2O2/HCl solution, Biomaterials 23(2002) 1353–1357.

DOI: 10.1016/s0142-9612(01)00254-x

[6] M. Ueda, R. Matsunaga, M. Ikeda, M. Ogawa, Hydrothermal crystallization of TiO2 gel films on Ti substrates and formability of hydroxyapatite, Mater. Trans. 49 (2008) 1706-1709.

DOI: 10.2320/matertrans.mrp2008132

[7] M. Ueda, M. Ikeda and M. Ogawa, Chemical-hydrothermal combined surface modification of titanium for improvement of osteointegration, Mater. Sci. Eng. C 29 (2009) 994–1000.

DOI: 10.1016/j.msec.2008.09.002

[8] M. Ueda, Y. Sasaki, M. Ikeda, M. Ogawa, W. Fujitani, T. Nakano, Chemical-hydrothermal synthesis of bioinert ZrO2-TiO2 films on pure Ti substrates and proliferation of osteoblast-like cells, Mater. Trans. 50 (2009) 2147-2153.

DOI: 10.2320/matertrans.maw200910

[9] H.W. Kang, K. Ida, Y. Yamamoto, H. Muramatsu, Monitoring of morphology and physical properties of cultured cells using a micro camera and a quartz crystal with transparent indium tin oxide electrodes after injections of glutaraldehyde and trypsin, Analytica Chimica Acta 2 (2008) 154-161.

DOI: 10.1016/j.aca.2008.06.037

[10] E. Watarai, R. Matsuno, T. Konno, K. Ishihara, M. Takai, QCM-D analysis of material–cell interactions targeting a single cell during initial cell attachment, Sensors and Actuators B: Chemical 171-172 (2012) 1297-1302.

DOI: 10.1016/j.snb.2012.05.010

[11] K. Kushiro, C.H. Lee, M. Takai, Simultaneous chacterization of protein-material and cell-protein interactions using dynamic QCM-D analysis on SAM surfaces, Biomaterials Science 4 (2016) 989-997.

DOI: 10.1039/c5bm00613a