Digital One-Step Competitive Detection of a Small Molecule in Synthetic and Environmental Waters

Area of Science:

• Analytical Chemistry
• Biotechnology
• Environmental Science

Background:

• Single-molecule analysis offers potential for highly accurate and sensitive detection of target molecules.
• Developing rapid and efficient methods for detecting small molecules in diverse water matrices is crucial for environmental monitoring and public health.

Purpose of the Study:

• To demonstrate an efficient optical biosensing approach for the competitive detection of small molecules in water.
• To validate the method's performance across various water qualities, including ultrapure water, river water, and wastewater effluent.

Main Methods:

• Utilized a single-DNA biochip for parallelized tethered particle motion real-time measurements.
• Employed antibodies and modified targets as molecular competitors for competitive assay design.
• Analyzed conformational changes in DNA tethers (looped to unlooped) indicative of target binding.

Main Results:

• Successfully detected fluorescein, a model target molecule, in various water samples.
• Achieved similar dose-response curves across different water qualities, from nanomolar to micromolar concentrations.
• Established a limit of detection for fluorescein around 2 nM.

Conclusions:

• The developed biosensing method is effective for sensitive and rapid detection of small molecules in diverse aquatic environments.
• The approach demonstrates robustness and consistent performance across varying water complexities.
• This technique holds promise for real-time environmental monitoring applications.