An integrated droplet based microfluidic platform for high throughput, multi-parameter screening of photosensitiser activity

摘要

With rapid advances in the field of cellomics, genomics, and proteomics, the demands for development of enabling technologies for performing high throughput biological experimentation are ever increasing. Droplet based microfluidic systems have recently been developed to perform high throughput experimentations. With the ability to generate droplets over 1 kHz frequency and perform combinatorial experiments via various passive and active manipulating techniques, microdroplet technology provides an ideal platform for combinatorial biological experiments whilst consuming minimal amount of reagent. As it is possible to generate droplets, manipulate them, and characterise droplets using highly sensitive on-line detection systems, it is now crucial to bring various functionalities together to create a micro total analysis system capable of performing complex biological experiments within microfluidic devices. As such, an integrated droplet based microfluidic platform was developed to assess the efficacy of photodynamic therapy against microbial organisms. Photodynamic therapy is an alternative efficacious treatment method for the treatment of localized microbial infections with several favourable features such as broad spectrum of action, efficient inactivation of multidrug-resistant bacteria, and low mutagenic potential. In order to perform the photosensitiser cytotoxicity screening, various microfluidic modules such as droplet generation, chamber based microdroplet storage and light irradiation, droplet reinjection, electrocoalescence and on-chip viability scoring of cells within droplets using a combination of carboxyfluorescein diacetate and propidium iodide were developed and integrated within the microfluidic platform. The microfluidic system was then used to screen the cytotoxicity of TBO against E.coli cells and the results were validated against conventional colony forming unit assays. Finally, the integrated system was used to assess the effects of several parameters on E.coli viability such as dark toxicity, photosensitiser concentration, light dose and poor oxygenation condition.