The Use of Lab on a Chip Devices to Evaluate Infectious Biofilm Formation and Assess Antibiotics and Nano Drugs Treatments
Authors: Bourguignon Natalia , Kamat Vivek A , Lerner Betiana , Perez Maximiliano , Bhansali Shekhar 
Published: February 2020

The microfluidics devices are identified as Lab On a Chip (LOC) and they consist of a network of microchannels that are compose by different sections, chambers, columns and reservoirs [1]. The LOC application to study organisms is an emerging field where the benefits of miniaturization of the system offer new opportunities to study and sense different bioprocesses. In addition, microorganisms form surface-adherent community structures called biofilms and these biofilms play a critical role in wound infections. Microbial biofilms have inherent defense and survival mechanisms including: avoidance of host inflammatory cells, resistance to antibiotics, and dynamic cell-cell communication pathways with gene exchange (Quorum Sensing), which inhibit wound healing [2]. Also nanoparticles targeting anti-biofilm therapy have gained recognition due to their unique features.

In this work we propose LOC as a platform for the formation of infectious biofilm in skin wounds and assess new treatments with antibiotics and nano drugs and these drugs have antimicrobial and anti-biofilm properties.

The microdevices were built with glass base and polydimethylsiloxane (PDMS) cover. PDMS was mixed with curing agent in a 10:1 ratio and then the mixture was placed under vacuum to remove air bubbles, poured onto the SU8-mold and cured in an oven at 80 °C overnight. The microchip design microchannels (Figure 1) allows for higher throughput with multiple channels are located in one chip (parallelized measurements). Each microchannel has 11 culture chambers with a height of 100 µm and an internal volume of 5.36 µL with. The microchannels were washed with 70% ethanol and were disinfected using NaOH (0.5 mol L-1) for 30 minutes. Pseudomonas aeruginosa and Propionibacterium acnes were used in a continuous culture either as a single culture or as co-culture in the microchip as a bioreactor for biofilm formation in the microchannels. After 3 days of culture good cell adhesions to the substrate and biofilm formation inside the microchannels were observed. Different concentrations of nanoparticles of silver, gold and antibiotics were evaluated for the inhibition of the infections biofilm.

After 48 h of each anti-biofilm treatment condition the physiological characteristics were analyzed by transcriptomics (RNAm sequencing) and the morphological characterization of biofilm architecture was evaluated by Scanning Electron Microscopy (SEM) and Confocal Scanning Laser Microscopy (CSLM).The results of this study show that the use of microchip as a culture system allows a good biofilm formation and is a valuable tool for quickly screening of antimicrobial activity of nano drugs in biofilms. This microchip can be used in drug testing and biomedical applications.

1- Whitesides, G.M., (2006). The origins and the future of microfluidics. Nature. 442(7101):368-373

2- Alvarado-Gomez, E., Martínez-Castañon, G., Sanchez-Sanchez, R., Ganem-Rondero, A., Yacaman, M. J., & Martinez-Gutierrez, F. (2018). Evaluation of anti-biofilm and cytotoxic effect of a gel formulation with Pluronic F-127 and silver nanoparticles as a potential treatment for skin wounds. Materials Science and Engineering: C, 92:621-630.

Figure 1