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.
Abstract: This paper describes the use of crossed laminar flow microfluidics for the selective capture of multiple cell types on-chip aiming for high throughput screening of various cell treatment compounds. Parallel laminar streams containing different cell types were perfused and captured on a cell adhesion protein-functionalized reaction area. Thereafter, parallel streams containing cell treatment solutions were delivered orthogonally over the captured cells. Multiple cell types and a range of cell treatment conditions could therefore be assessed in a single experiment. We were also able to sort mixed cell populations via antibody array clusters, and to further deliver treatments to subpopulations of cells. Moreover, using solutions with different tonicities, we successfully demonstrated the incorporation of a live/dead cell viability assessment on-chip for a direct read out assay following the treatments. This crossed laminar flow microfluidics for generation of a cell-based assay could therefore offer an interesting platform for high throughput screening of potential drug candidates, nanoparticle toxicity testing, or other cellular and molecular interventions.
Pub.: 12 Jan '17, Pinned: 12 Mar '18
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
Abstract: With advances in nanotechnology, particles with various size, shape, surface chemistry, and composition can be easily produced. Nano- and microparticles have been extensively explored in many industrial and clinical applications. Ensuring that the particles themselves are not possessing toxic effects to the biological system is of paramount importance. This paper describes a proof of concept method, in which a microfluidic system is used in conjunction with a cell microarray technique aiming to streamline the analysis of particle-cell interaction in a high throughput manner. Polymeric microparticles, with different particle surface functionalities, were first used to investigate the efficiency of particle-cell adhesion under dynamic flow. Silver nanoparticles (AgNPs, 10 nm in diameter) perfused at different concentrations (0 to 20 μg/mL) in parallel streams over the cell microarray exhibited a higher toxicity compared to the static culture in the 96-well-plate format. This developed microfluidic system can be easily scaled up to accommodate a larger number of microchannels for high throughput analysis of the potential toxicity of a wide range of particles in a single experiment.
Pub.: 03 Mar '18, Pinned: 12 Mar '18