Integrated lab-on-chip technology for zebrafish embryo sorting and larvae immobilization for drug discovery

The major current hurdle to widespread deployment of zebrafish embryos and larvae in large-scale drug discovery is the problem of enabling analytical platforms with high throughput. In order to spearhead drug discovery using zebrafish as a model, platforms need to determine pre-test sorting of organisms to ensure quality control and standardisation, and determine that their in-test positioning is suitable for high-content imaging with modules for flexible drug delivery. Manual procedures for sorting hundreds of embryos are very monotonous and therefore liable to significant analytical errors caused by operators’ fatigue. In this thesis, we present an innovative proof-of-concept design for a micromechanical large-particle in-flow sorter.<br><br>This thesis investigated infra-red sensor detection and image acquisition and compared them for their ability to distinguish between viable and dead embryos. High-definition additive manufacturing systems for fabrication of 3D printed moulds of the type used in soft lithography were also explored. 3D printing using SLA provides a rapid microfabrication of the moulds with high definition and optical transparency, as is confirmed by both scanning electron microscopy and confocal microscopy. SLA technologies may be applied for the rapid and accurate fabrication of millifluidic devices that can trap millimetre-sized specimens such as living zebrafish larvae. We applied this new manufacturing method in a proof-of-concept prototype device capable of trapping and immobilising living zebrafish larvae for the purpose of recording heart rate variations in cardio-toxicity experiments.<br><br>Static conventional culture plates limit the throughput data, and is not suitable for modern compound library screening, while currently available conventional microtiter well plates require manual pipetting, which is labour intensive and time consuming. This research offers promising avenues for the development of a miniaturised, automated system for handling and manipulating zebrafish embryos and larvae, using innovative microfluidic lab-on-chip (LOC) technologies and additive manufacturing technologies.