Controlled PAH-mediated method with enhanced optical properties for simple, stable immunochromatographic assays

Area of Science:

• Analytical Chemistry
• Nanotechnology
• Biotechnology

Background:

• Metal growth methods enhance signal amplification in gold nanoparticle-based immunochromatographic assays (AuNP-ICA).
• Existing methods suffer from non-specificity and lack robust growth control, limiting practical application.
• Sensitive detection of food-borne pathogens like Escherichia coli O157:H7 is crucial for public health.

Purpose of the Study:

• To develop a novel polyallylamine hydrochloride (PAH)-mediated metal growth strategy for AuNP-ICA.
• To enhance colorimetric signal amplification for improved detection sensitivity.
• To establish a stable and reproducible method for detecting Escherichia coli O157:H7.

Main Methods:

• Utilized polyallylamine hydrochloride (PAH) as a controlled growth framework for copper (Cu) shell deposition on gold nanoparticles (AuNPs).
• Applied the PAH-mediated AuNP probes in an immunochromatographic assay (ICA) for Escherichia coli O157:H7 detection.
• Investigated the effect of PAH on non-specific adsorption and signal-to-noise ratios.

Main Results:

• Achieved highly controlled Cu shell growth on AuNPs, leading to significantly enhanced colorimetric signals.
• Eliminated non-specific adsorption of Cu ions on the nitrocellulose membrane, maximizing signal-to-noise ratios.
• Established a detection limit of 9.8 CFU/mL for Escherichia coli O157:H7 with good reproducibility (CV <13%) and stability.

Conclusions:

• The PAH-mediated metal growth method provides a robust and effective signal enhancement strategy for AuNP-ICA.
• This approach enables rapid, stable, and highly sensitive detection of food-borne pathogens.
• The developed system holds potential for broader applications using various metal growth schemes (Au, Ag, etc.).