In flow metal-enhanced fluorescence for biolabelling and biodetection

Area of Science:

• Nanotechnology
• Microbiology
• Analytical Chemistry

Background:

• Accurate detection and quantification of bacteria like Escherichia coli are crucial for public health and environmental monitoring.
• Traditional methods for bacteria detection can be time-consuming and lack sensitivity.
• Metal Enhanced Fluorescence (MEF) offers a promising approach to enhance signal detection in biological samples.

Purpose of the Study:

• To develop and evaluate ultraluminescent core-shell nanoparticles for labeling and detecting Escherichia coli.
• To utilize Metal Enhanced Fluorescence (MEF) for enhanced signal amplification in bacteria imaging and flow cytometry.
• To establish a sensitive and reliable method for quantifying E. coli in water samples.

Main Methods:

• Synthesis of core-shell nanoparticles with a 40 nm core, silica spacer, and Rhodamine B (RhB) for fluorescence.
• Application of nanoparticles for non-covalent, ultraluminescent labeling of E. coli via hydrophilic silica spacer interaction.
• Detection and imaging using Laser Fluorescence Microscopy and quantification using flow cytometry, analyzing Side-scattered light (SSC) and Forward-scattered light (FSC).

Main Results:

• Bright and well-defined imaging of labeled E. coli was achieved using Laser Fluorescence Microscopy.
• Flow cytometry successfully detected labeled E. coli, showing increased SSC, FSC, and fluorescent event counts compared to unlabeled bacteria.
• The methodology demonstrated good sensitivity, enabling accurate quantification of E. coli in fortified water samples.

Conclusions:

• Ultraluminescent core-shell nanoparticles based on MEF provide an effective tool for sensitive E. coli detection and imaging.
• The developed nano-labeling technique offers a non-covalent, efficient approach for bacteria identification.
• This method shows potential for routine water quality monitoring and bacterial quantification applications.