Microfluidic system for genotoxicity testing of biomaterials

This research summary written by Varvara Gribova describes a new automated microfluidic-based method for the genotoxicity testing of new biomaterials.

The peer-reviewed article “A miniaturized genotoxicity evaluation system for fast biomaterial-related risk assessment” was co-authored by Jesus Manuel Antunez Dominguez, Alan Morin, Julia Sepulveda Diaz, Philippe Lavalle, and Nihal Engin Vrana and published in Analytical Methods in February 2023.

Abstract

Genotoxicity testing is an important aspect of biocompatibility assessment of new materials being developed for biomedical applications. However, the classic genotoxicity test (Ames test) is complex and requires much space; therefore, it is rarely used by biomaterials researchers. In this work, we introduce a new simplified genotoxicity test that takes place in a microfluidic chip. Our test is faster and requires significantly less material and space. In addition, an automatization option with a microfluidics-based control system has also been designed. We believe that this simplified system will allow researchers to evaluate genotoxicity earlier during materials’ development, thus contributing to their increased safety for the patients.

Introduction | Optimizing genotoxicity testing for biocompatibility

The goal of the project was to miniaturize and simplify the traditional microbiological Ames test that takes place in Petri dishes (d = 10 cm), requires a lot of space and includes an agar heating step.¹ The test uses pathogenic Salmonella typhimurium bacteria, which are able to grow only when treated with a mutagen.

We also propose an automatized system that will limit the contact of researchers with pathogenic microorganisms, ensuring a safer genotoxicity testing protocol.

Aims

• Create a simplified genotoxicity test readily available to biomaterials researchers.
• Make the test adaptable to standard biomaterials laboratories.
• Automatize and customize the testing chamber and the microfluidic control system to optimize and improve the availability of genotoxicity testing of biomaterials.

Experiment setup | Creating a faster genotoxicity detection method

We designed a microfluidic chip (2.55 x 7.55 cm), allowing us to perform three genotoxicity testing in parallel (Figure 1), and a faster genotoxicity detection method using fluorescent labelling of bacteria.

Materials

• Oxoid #2 medium, minimal glucose agar plates, nutrient agar plates, histidine/biotin 0.5 mM solution, typhimurium TA100 strain, NaN₃ (Trinova Biochem, Germany).
• Agar (Sigma)
• SYTO™24 green fluorescent nucleic acid stain (Invitrogen).
• Biocompatible resin BioMed Clear (FormLabs, France)
• 3D printer Mars 2 Pro with a 2K mono LCD (ELEGOO, China)
• Mux wire valve controller (Elvefow, France) operated via the ESI software
• Elveflow Cobalt Autonomous Microfluidic Pump

Key findings | A faster, safer, and effective testing protocol

We developed a new approach to genotoxicity testing using fluorescent labelling of bacteria instead of colony formation test (classic Ames test). This method allows the detection of mutant bacteria after only 24 hours of incubation, compared to 48 hours necessary for the classic test.

In addition, we miniaturized the test, moving from Petri dishes (d = 10 cm) to 6-well plates (Figure 2A) and finally to a microfluidic chip (Figure 2B).

The miniaturized genotoxicity test can be performed manually, but we also propose an automated option using a Mux wire valve controller (Figure 3) (Elvefow, France).

Conclusions | A novel microfluidic approach for testing biocompatibility

In this work, we developed a microfluidic genotoxicity testing approach, which significantly reduces the space and time required for the test compared to the classic Ames test. An automatization option with a microfluidics-based control system has also been designed to reduce the contact of researchers with pathogenic bacteria.

We believe that our system can contribute to better genotoxicity testing and evaluations of new materials and molecules and thus to increasing the safety for the patients.