An automated microreactor for semi-continuous biosensor measurements.

Area of Science:

• Synthetic Biology
• Microfluidics
• Biosensing

Background:

• Living cells, particularly bacteria and yeast, serve as bioreporters for detecting chemical analytes and sample toxicity.
• Synthetic gene circuitry enables these cells to produce reliable signals, like fluorescence or bioluminescence, in response to specific targets, forming flexible analytical platforms.

Purpose of the Study:

• To adapt bacterial cells expressing fluorescence reporters (bactosensors) for automated, semi-continuous target analysis on a microfluidic biochip.
• To demonstrate the utility of this bactosensor chip for real-time environmental monitoring.

Main Methods:

• Engineered Escherichia coli bactosensor cells were continuously cultured in nanoliter-volume reactors integrated into a microfluidic chip.
• Cells were directed to a sample exposure area for concentration and reaction with target chemicals, triggering localized fluorescent reporter signals.
• The system's performance was evaluated for automated arsenite detection.

Main Results:

• The bactosensor chip enabled automated, semi-continuous detection of 50 μg/L arsenite in water over consecutive days and one week of continuous operation.
• Optimal bactosensor induction (6-9 fold) was achieved at a dilution rate of 0.12 h⁻¹ in a 50 nl microreactor.
• The system demonstrated robust and reliable performance in detecting the target analyte.

Conclusions:

• The developed bactosensor chip offers a novel approach for automated, semi-continuous analysis using engineered microbial cells.
• This technology has broad applicability for constructing automated monitoring devices for diverse targets in various environmental settings.