Nonlabeled quartz crystal microbalance biosensor for bacterial detection using carbohydrate and lectin recognitions

Area of Science:

• Biotechnology
• Biosensor Technology
• Microbiology

Background:

• Harmful microbes bind to human cells via specific carbohydrate sequences.
• Lectins are known to interact with bacterial and fungal structures.
• Microorganisms possess both carbohydrate and lectin binding sites on their surface.

Purpose of the Study:

• To develop a sensitive and specific biosensor for detecting high molecular weight bacterial targets.
• To utilize a carbohydrate nonlabeled mass sensor combined with lectin-bacterial O-antigen recognition.
• To enhance bacterial adhesion and detection using molecular recognition elements.

Main Methods:

• A quartz crystal microbalance (QCM) transducer was employed.
• A mannose self-assembled monolayer and concanavalin A (Con A) lectin were used as recognition elements.
• Detection of Escherichia coli (E. coli) was performed using these components.

Main Results:

• The developed biosensor demonstrated high sensitivity and specificity for E. coli detection.
• A detection limit of a few hundred bacterial cells was achieved.
• A wide linear range (7.5 x 10^2 to 7.5 x 10^7 cells/mL) and rigid bacterial attachment were observed.
• Minimal nonspecific binding to other bacteria and proteins was noted.

Conclusions:

• The novel approach overcomes challenges in QCM-based bacterial detection.
• Combining carbohydrate and lectin recognition significantly enhances biosensor specificity and sensitivity.
• This method is suitable for fast, on-line screening of bacteria in various applications, including food, water, and clinical settings.