Investigation of the Effect of Channel Structure and Flow Rate on On-Chip Bacterial Lysis

Abstract

Successful lysis of cells/microorganisms is a key step in the sample preparation in fields like molecular biology, bioengineering, and biomedical engineering. This study therefore aims to investigate the lysis of bacteria on-chip and its dependence on both microfluidic channel structure and flow rate. Effects of temperature on lysis on-chip were also investigated. To perform these investigations, three different microfluidic chips were designed and produced (straight, zigzag and circular configurations), while the length of the channels were kept constant. As an exemplary case, Mycobacterium smegmatis was chosen to represent the acid-fast bacteria. Bacterial suspensions of 1.5 McFarland were injected into the chips at various flow rates (0.6-8 µl/min) either at room temperature or 50° C. In order to understand the on-chip lysis performance fully, off-chip experiments were carried out at durations which are equal to those bacteria spent in the channel from inlet to the outlet at different flow rates. We also performed COMSOL multiphysics program simulations to evaluate further the effect of the applied parameters. As a result, we found that the structure and the flow rate do not affect lysis over all in all investigated channel types, however on-chip experiments at room temperature produced more effective lysis compared to the on-chip and the off-chip samples performed at higher temperatures. Interestingly on-chip experiments at higher tempratures do not result in effective lysis. Index Terms-Microfluidic chip, Thermal lysis, On-chip bacterial lysis, Mycobacterium smegmatis I. INTRODUCTION acterial infections have continued to be a major cause of human morbidity and mortality [1]. Among them, tuberculosis and leprosy are categorized as acid-fast bacteria diseases since they could resist decolorization in acid, and these bacteria are responsible for millions of deaths each year and a great effort has been made by health institutions to control these This study was conducted in the frame of a Newton Katip Celebi Fund between Turkey and UK and supported by Turkish Scientific and Technological Council under the grant number of 217S793.

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