Particle Diffusometry: An Optical Detection Method for Vibrio cholerae Presence in Environmental Water Samples

Area of Science:

• Environmental microbiology
• Biosensor technology
• Nucleic acid detection

Background:

• Current diagnostics struggle with rapid, sensitive detection of low pathogen concentrations in complex sample matrices.
• Nucleic acid amplification methods, while standard, face challenges in robustly detecting minimal pathogen levels without enrichment.
• Existing methods lack the sensitivity and speed required for real-time environmental pathogen monitoring.

Purpose of the Study:

• To develop a rapid, robust, and sensitive biosensor for detecting low pathogen concentrations.
• To utilize particle diffusometry for measuring amplified nucleic acids and assessing pathogen presence.
• To demonstrate the biosensor's efficacy using Vibrio cholerae (V. cholerae) in environmental water samples.

Main Methods:

• Amplified nucleic acids were combined with fluorescent particles.
• Changes in particle diffusion coefficients were measured using particle diffusometry.
• Vibrio cholerae was used as a model pathogen in molecular-grade and pond water samples.

Main Results:

• Detection of as few as 1 V. cholerae cell in molecular-grade water within 20 minutes.
• Detection of 10 V. cholerae cells in pond water within 35 minutes, demonstrating environmental relevance.
• Particle diffusometry showed 10-fold higher sensitivity compared to standard fluorescence detection of nucleic acid amplification.

Conclusions:

• Particle diffusometry offers a highly sensitive and rapid method for pathogen detection in environmental samples.
• The developed biosensor eliminates the need for sample enrichment or purification steps.
• This technique is a promising advancement for real-time, low-level pathogen detection in native environments.