Selective Uropathogenic E. coli Detection Using Crossed Surface-Relief Gratings.

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Optical Sensing

Background:

• Urinary tract infections (UTIs) are a significant global health issue, often caused by uropathogenic Escherichia coli (UPEC).
• Rising antimicrobial resistance necessitates rapid and accurate UPEC detection methods.
• Current diagnostic approaches can be slow and costly, hindering timely treatment.

Purpose of the Study:

• To develop a real-time, selective, and label-free detection platform for UPEC.
• To utilize crossed surface-relief gratings (CSRGs) as nanometallic sensors for enhanced sensitivity.
• To create an inexpensive point-of-care diagnostic tool for UTIs.

Main Methods:

• Incorporation of CSRGs into an optical sensing platform for surface plasmon resonance (SPR) detection.
• Experimental validation using bulk refractive index (RI) measurements to determine sensitivity and resolution.
• Demonstration of selective UPEC capture and detection in phosphate-buffered saline (PBS) against other Gram-negative bacteria.

Main Results:

• The platform achieved a bulk sensitivity of 382.2 nm/RIU and a resolution of 10^-6 RIU.
• Real-time, selective detection of UPEC was demonstrated for the first time using CSRGs.
• The detection limit for UPEC was 10⁵ CFU/mL, with a dynamic range of four orders of magnitude.

Conclusions:

• CSRG-based optical sensing offers a promising approach for rapid and accurate UPEC detection.
• This technology can facilitate the development of cost-effective point-of-care devices for UTI diagnosis.
• Improved UTI diagnostics can aid in effective treatment and reduce the burden of recurrent infections.