Sensitive detection of active Shiga toxin using low cost CCD based optical detector

Area of Science:

• Food safety and diagnostics
• Biotechnology and biosensing
• Microbiology and toxicology

Background:

• Foodborne illnesses necessitate sensitive detection of active toxins like Shiga toxin type 2 (Stx2).
• Current immunoassays cannot differentiate between active and inactive toxin forms, limiting clinical relevance.
• There is a need for affordable, sensitive diagnostic tools for active toxin detection.

Purpose of the Study:

• To develop and evaluate a low-cost fluorescence detection system for measuring active Shiga toxin type 2 (Stx2) activity.
• To compare the performance of a charge-coupled device (CCD) based system with a commercial fluorometer.
• To demonstrate a clinically relevant method for toxin detection that is more accessible.

Main Methods:

• A low-cost fluorescence detection system was constructed using a CCD camera and LED excitation source.
• The system measured green fluorescent protein (GFP) inhibition by Shiga toxin.
• The system's performance was evaluated for detecting active Stx2 and compared to a commercial fluorometer.

Main Results:

• A negative linear relationship was observed between Stx2 concentration and GFP luminous intensity (R²=0.85 for CCD, R²=0.86 for fluorometer).
• The low-cost CCD system detected Stx2 activity at levels comparable to an expensive commercial fluorometer.
• The system demonstrated sensitivity in the range of 100 ng/mL to 0.01 pg/mL.

Conclusions:

• Low-cost CCD-based fluorescence detection is a viable and sensitive method for measuring active Shiga toxin activity.
• This approach offers a clinically relevant and affordable alternative to traditional immunoassays.
• The technology has the potential to increase the availability of foodborne bacterial toxin diagnostics, especially in resource-limited settings.