Optical biosensors for bacteria detection by a peptidomimetic antimicrobial compound

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Label-free biosensors offer advantages over traditional methods.
• Antimicrobial peptides (AMPs) show potential for targeted molecular recognition.
• Porous silicon nanostructures are effective optical transducers.

Purpose of the Study:

• To develop and characterize a novel label-free optical biosensor for rapid bacteria detection.
• To utilize a synthetic peptide-mimetic compound as the recognition element.
• To demonstrate sensitive and reproducible detection of Escherichia coli (E. coli).

Main Methods:

• Functionalization of oxidized porous silicon (PSiO2) nanostructures with a synthetic peptide-mimetic (K-7α12).
• Monitoring changes in the reflectivity spectrum upon exposure to bacterial suspensions and lysates.
• Evaluating biosensor performance with varying concentrations of E. coli.

Main Results:

• The biosensor detected E. coli cell fragments with high sensitivity (down to 10(3) cells/mL).
• Optical response was proportional to E. coli concentration in bacterial lysates.
• Intact bacterial cells showed poor capture and insignificant optical response.
• Preferential capture of E. coli fragments was observed over Gram-positive and other Gram-negative bacterial lysates.

Conclusions:

• The developed OAK-based biosensor provides a rapid, sensitive, and reproducible method for E. coli detection.
• This approach offers advantages over antibody-based assays, including simple and cost-effective production.
• The peptide-mimetic functionalization strategy allows for customizable detection schemes.