Raja K. Vadivelu, Chin Hong Ooi, Nam-Trung Nguyen*

Griffith University, 170 Kessels Road, 
Nathan 4111, Queensland, Australia.


The liquid marble (LM) is a reliable bioreactor suitable for growing three-dimensional (3D) tissue models such as spheroids and toroids. Furthermore, a LM also serves as a bioassay with in vivo relevance. A LM is created by coating a liquid droplet containing cells with micro-sized hydrophobic powder.1 The encapsulation creates a porous shell that allows gas exchange for growing cells. Furthermore, the LM can float on a liquid bath, of which the LM can move across with little resistance.2 Manipulation of the LM motion could generate internal flows which allow the cells within to distribute and associate freely. The LM can be driven across the liquid surface via magnetic3 or surface tension gradient force.4 Recently, the LM has been used to grow multiple spheroids of olfactory ensheathing cells (OEC) and co-cultures with Schwann cells and astrocyte.5 We explore further by embedding a hydrogel sphere containing growth factor into a LM filled with a suspension of dissociated cells. The hydrogel acts as a slow-release carrier. This platform is suitable for the assessment of chemotaxis dependent cell migration, aggregation and self-assembly of cells into toroidal aggregates. On the other hand, LM’s coalesce upon collision at high Weber numbers. Thus, a simple bioassay can be developed to analyze cell interaction between distinct niches by coalescing multiple LM’s with different microenvironments.6 It is envisioned that the versatility of LM as a microbioreactor could contribute substantially to therapeutic applications and developing organoids.

1 Aussillous, P.; Quere, D., Proc. R. Soc. A 2006, 462 (2067), 973-999, Properties of liquid marbles.
2 Ooi, C. H.; Nguyen, A. V.; Evans, G. M.; Dao, D. V.; Nguyen, N. T., Sci. Rep. 2016, 6, 38346, Measuring the Coefficient of Friction of a Small Floating Liquid Marble.
3 Khaw, M. K.; Ooi, C. H.; Mohd-Yasin, F.; Vadivelu, R.; John, J. S.; Nguyen, N.-T., Lab on a Chip 2016, 16 (12), 2211-2218, Digital microfluidics with a magnetically actuated floating liquid marble.
4 Ooi, C. H.; Nguyen, A. V.; Evans, G. M.; Gendelman, O.; Bormashenko, E.; Nguyen, N.-T., RSC Adv. 2015, 5 (122), 101006-101012, A floating self-propelling liquid marble containing aqueous ethanol solutions.
5 Vadivelu, R. K.; Ooi, C. H.; Yao, R. Q.; Tello Velasquez, J.; Pastrana, E.; Diaz-Nido, J.; Lim, F.; Ekberg, J. A.; Nguyen, N. T.; St John, J. A., Sci. Rep. 2015, 5, 15083, Generation of three-dimensional multiple spheroid model of olfactory ensheathing cells using floating liquid marbles.
6 Vadivelu, R. K.; Kamble, H.; Munaz, A.; Nguyen, N.-T., Biomedical microdevices 2017, 19 (2), 31, Liquid marbles as bioreactors for the study of three-dimensional cell interactions.

Biographic Details
Name: (Prof.) Nam-Trung Nguyen
Phone: + (617) 373 53921  E-mail: nam-trung.nguyen@griffith.edu.au
Name: (Mr.) Raja K. Vadivelu
Phone: + (617) 373 58010  E-mail: raja.vadivelu@griffithuni.edu.au
Name: (Dr.) Chin Hong Ooi
Phone: + (617) 373 58008  E-mail: chinhong.ooi@griffithuni.edu.au

Affiliation, Country: Queensland Micro- and Nanotechnology Centre, Griffith University, Australia