Microfluidic strategies for on-chip culture of bacterial whole-cell biosensors

Abstract

The increasing heavy metal pollution of our water supplies is a cause for grave concern. Due to the rapid industrialisation during the 20th and the 21st century, our lakes, oceans and rivers have seen a rise in contamination due to heavy metal particles, a by-product of industrial and mining waste. Heavy metals such as cadmium, lead, mercury, zinc, etc. have been demonstrated to have catastrophic effects to whole ecosystems. More importantly, these heavy metal particles can often enter cities’ water supplies and end up causing grave health problems to a larger part of the population. Heavy metal poisoning has been widely demonstrated to affect many vital organs, causing chronic conditions and even death. For this purpose, testing has become a habitual and important process when assessing the quality of our water supplies. Water testing for heavy metal particles has historically been championed by atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectroscopy (ICP-MS), and electrochemical sensors. Nonetheless, these methods are low-throughput, costly and non-portable, making testing in remote areas troublesome. A novel technique, with the use of genetically modified whole-cell bacteria has been proposed to overcome these problems. Bacterial whole-cell biosensors are a low cost, high-throughput, sensitive alternative to traditional water quality assays. Bacterial whole-cell biosensors are amenable to miniaturization. Therefore, microfluidic cell culturing becomes a great candidate for miniaturising these assays. In this thesis several microfluidic approaches are introduced for bacterial on-chip cell culture. Additionally, a single-layer microfluidic valve is presented and fabricated to culture bacterial biosensors. The results indicate that the LOD of this bacterial biosensor is of 44.8 ppb for cadmium heavy metal particles.

Date of Award	2020
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology