A pinboard by
Scott McCormick

PhD Student, University of South Australia


A high-throughput microfluidic platform for testing toxicity of nanomaterials on human cells

The ever-expanding catalogue of nanomaterials in modern industry and society is leading to a rise in potential nanotoxicants that can be introduced to human biology. In order to screen for toxic effects, current methodologies employ large scale static methods that do not account for damage caused by the circulation and motion of nanomaterials that is possible in the human body. To improve upon this system, we propose a microfluidic device that can capture and culture multiple human cell types inside microchannels, which can then be exposed to multiple toxicological conditions per device. The controlled flow possible in microfluidics will improve the speed and ease of testing, and the device design will allow for microscopy techniques to improve and eventually automate cell viability counting.

Our research has included a device for the combined exposure of both nanomaterials and irradiation – in this case, ultraviolet light. We have tested nanoscale titanium dioxide, known for its photocatalytic nature, to determine whether it leads to increased cytotoxicity with or without the presence of UV. The device allows for a 2x2 grid of toxicological parameters to be produced with perpendicular irradiation, creating multiple analysis areas per device.


Optimization of binding B-lymphocytes in a microfluidic channel: surface modification, stasis time and shear response.

Abstract: Binding and maintaining cells inside microfluidic channels is a challenging task due to the potential release of cells from the channels with the flow and accompanying shear stress. In this work we optimized the binding of human B-lymphocyte cells (HR1K) inside a microfluidic channel and determined the strength of this binding under shear stress of flowing liquid. In order to determine the parameters required for a live/dead test in microfluidic devices, populations of both living and dead cells were tested separately. Channels were prepared in glass-polydimethylsiloxane hybrid chips, with a self-assembled monolayer of 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) before covalently immobilizing anti-CD20 antibody. Without GPTMS linker, ~90% of the CD20-expressing cells detached at 200 μL/min (the highest flow rate studied). With GPTMS linker, the bonding method proved critical for sustained immobilization of HR1K cells under flow. Masking the channel area during plasma bonding preserves the antibody functionality; the masked surface gives 15% cell detachment at 200 µL/min compared with 80% for an unmasked surface. Sealing the chip via clamping (without plasma treatment) was similar to masked plasma treatment (20% detachment) and allowing a post-adhesion stasis time (30 min) did not significantly change the relative cell detachment for the flow rates studied. Membrane integrity and calcium spiking behaviour were measured fluorescently, and demonstrated that the live cells retained comparable functionality to unanchored cells for the duration of the flow experiments. Non-viable HR1K cells were found to detach more readily, exhibiting only 20% cell retention at 200 μL/min compared with > 80% for live cells.

Pub.: 24 Oct '17, Pinned: 12 Mar '18