Optimizing immunomagnetic separation for efficient E. coli O157:H7 recovery and detection

TL;DR

This study optimizes immunomagnetic separation to efficiently detect E. coli O157:H7 in ground beef by adjusting factors like antibody concentration, temperature, and incubation time.

Contribution

The study identifies optimal conditions for immunomagnetic separation to maximize E. coli O157:H7 recovery and detection.

Findings

Lower IgG dilutions (1:100) result in higher binding efficiency of E. coli O157:H7 to immunomagnetic beads.

An incubation temperature of 32°C is optimal for bead-cell interactions, with deviations reducing binding efficiency.

Longer incubation times (up to 120 min) improve antibody coating on beads, enhancing target cell capture.

Abstract

Immunomagnetic separation is an invaluable tool in biomedical and food safety applications due to their high specificity and efficiency in capturing target cells. This study is a comprehensive investigation of the Ag-Ab reaction and the effects of several factors such as IgG concentration, incubation temperature, and incubation time on the binding efficiency of target cells to the immunomagnetic beads aiming to maximize captured E. coli O157 cells from ground beef samples. Our findings reveal a concentration-dependent relationship between IgG dilution and binding efficiency, with lower dilutions (1:100) yielding higher binding percentages. Additionally, the optimal incubation temperature for bead-cell interactions was identified as 32 °C, with deviations above or below this temperature impairing binding efficiency. Longer incubation times (up to 120 min) significantly improved antibody coating on the beads, enhancing their ability to capture target cells. The study also demonstrated a strong correlation between bacterial load and binding efficiency, highlighting the sensitivity of the immunomagnetic separation method in detecting E. coli O157 even at low concentrations. These findings underscore the importance of precisely controlling experimental parameters to maximize the efficiency and specificity of immunomagnetic separation techniques, providing a valuable framework for researchers aiming to refine bead-based cell capture protocols for diagnostic or research applications.

The online version contains supplementary material available at 10.1186/s13568-025-01991-6.

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