Microorganisms recognition and quantification by lectin adsorptive affinity impedance

Area of Science:

• Electrochemistry
• Biosensors
• Microbiology

Background:

• Accurate and rapid detection of bacteria is crucial for public health and diagnostics.
• Existing methods often require labeling or complex procedures, limiting their applicability.
• Lectin-carbohydrate interactions offer a specific recognition mechanism for microbial surfaces.

Purpose of the Study:

• To develop and evaluate a label-free impedimetric biosensor for bacteria detection.
• To utilize lectin-functionalized screen-printed gold electrodes (SPEs) for selective bacterial recognition.
• To demonstrate the capability of electrochemical impedance spectroscopy (EIS) for quantifying bacteria.

Main Methods:

• Screen-printed gold electrodes were modified with biotinylated Concanavalin A (Con A).
• Bacteria (e.g., Escherichia coli) were captured via lectin-carbohydrate binding, forming a complex in solution.
• Electrochemical impedance spectroscopy (EIS) was used to measure changes in electron transfer resistance upon complex adsorption onto the electrode surface.

Main Results:

• The biosensor demonstrated specific binding of Con A to E. coli, with no significant non-specific adsorption.
• The impedimetric response showed a linear relationship with the logarithm of E. coli concentration over four orders of magnitude.
• Principal component analysis (PCA) of responses from nine lectins and three bacteria (E. coli, Staphylococcus aureus, Mycobacterium phlei) enabled distinct bacterial classification.
• Electrochemical monitoring of beta-galactosidase activity further differentiated between E. coli and S. aureus.

Conclusions:

• Lectin-based SPEs combined with EIS provide a sensitive and label-free platform for bacteria detection and identification.
• The developed biosensor exhibits high selectivity and a broad linear range for E. coli quantification.
• This approach offers a promising tool for rapid microbial analysis in various applications.