Development and validation of a microfluidic reactor for biofilm monitoring via optical methods

Abstract

We present the design, fabrication, and verification of a microfluidic platform for optical monitoring of bacterial biofilms. Biofilm formation characterizes the majority of infections caused by bacteria that are developing increased resistance to traditional antibiotic treatment, necessitating the development of reliable tools not only for study of biofilm growth, but also for in situ examination of the response to applied stimuli. The presented platform was used to continuously and non-invasively observe the dependence of Escherichia coli biofilm formation on bacterial signaling by monitoring the change in biofilm optical density over the growth period. Results were corroborated by measurement of biofilm morphological properties via confocal microscopy, and statistical analysis was applied to verify the repeatability of observed optical and morphological differences in the biofilms formed. The presented platform will be used to characterize biofilm formation and response in drug discovery applications.

Critical review on biofilm methods

“…However, on-chip detection is normally desired to get a fully integrated device or to observe in situ and real time effects. Optical detection methods are often employed (Meyer et al, 2011;Zhu et al, 2013) in particular fluorescence (Johnson & Landers, 2004). Many studies have applied microfluidic technology due to its remarkable potentials: small liquid volume control, confining cells and molecules in a spatial geometry, temperature control and precise gradient generation, enabling low cost, rapid and precise analysis.…”

“…Custom-made microfluidic devices using PDMS techniques for manufacturing have been employed by several groups, e. g. systems where compartments are separated by a semi-diffusible membrane to allow the study of nutrient or signal molecules Skolimowski et al, 2010Skolimowski et al, , 2012, a system employing a micro-structured surface to study filamentous biofilm (steamer) formation (Hassanpourfard et al, 2014), a simple device for easy microscopic investigations of biofilms using reflection confocal microscopy (Yawata et al, 2010), a system to study the influence of shear stress due to changes in flow conditions (Salta et al, 2013), a system to allow the assessment of the effects of antibiotics in an on-line mixing system (Terry & Neethirajan, 2014), and a system to online study the development of biomass (biofilm thickness) (Meyer et al, 2011). The general usability of microfluidic techniques is, however, still limited by the difficulty of the methodology and the skills needed for successful employment.…”

AI-2 analogs and antibiotics: a synergistic approach to reduce bacterial biofilms

“…1) was described in Meyer et al (2011). The device base is a coverslip, which provides a transparent substrate thin enough for highresolution confocal microscopy.…”

Platforms for Engineering Experimental Biomedical Systems

“…Sensing of this transmission is achieved via an array of photopixels placed underneath of the microfluidic growth chamber, where the analog voltage outputs of the pixels are inversely proportional to the biofilm optical density at that point. The advantage of this sensing mechanism is that it provides a means of non-invasive and continuous detection of biofilm growth that is otherwise difficult to obtain (Meyer 2011). Additional study of the biofilm is achievable through end-point measurements of density and morphology through the use of confocal microscopy.…”