Quantitative protein detection using single molecule imaging enzyme-linked immunosorbent assay (iELISA)

Area of Science:

• Molecular Biology
• Biotechnology
• Immunology

Background:

• Protein detection is crucial for molecular biology research, pathogen testing, and disease diagnostics.
• Accurate quantification of specific proteins, like the porcine circovirus type 2 (PCV2) Cap protein, is essential for disease monitoring and research.
• Existing methods for protein detection can be time-consuming, requiring extensive sample preparation.

Purpose of the Study:

• To develop and validate a single molecule imaging enzyme-linked immunosorbent assay (iELISA) for quantitative detection of PCV2 Cap protein.
• To assess the speed, selectivity, and sensitivity of the proposed iELISA method.
• To demonstrate the potential of iELISA for fast trace protein detection.

Main Methods:

• Utilized a monoclonal antibody against PCV2 Cap protein immobilized on a polyethylene glycol (PEG) passivated slide via biotin-streptavidin interaction.
• Employed fluorescein isothiocyanate (FITC)-labeled secondary antibodies for detection.
• Employed total internal reflection fluorescence microscopy for single-molecule imaging and quantification.

Main Results:

• Achieved quantitative measurement of PCV2 Cap protein at the single-molecule level.
• Demonstrated that iELISA measurements can be completed within 1 hour, bypassing lengthy sample preparation.
• Obtained a linear relationship between fluorescent signals and the logarithm of target protein concentrations, with a detection limit of 7 ng/mL.
• Showcased excellent protein selectivity and anti-interference capabilities.

Conclusions:

• The single molecule iELISA is a rapid, accurate, and sensitive method for quantifying PCV2 Cap protein.
• The developed iELISA method offers significant advantages in terms of speed and simplicity compared to traditional assays.
• This technique holds potential for broad applications in fast trace protein detection for diagnostics and research.