Selective detection of bacteria in urine with a long-range surface plasmon waveguide biosensor

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microbiology

Background:

• Urinary tract infections (UTIs) are common, necessitating sensitive diagnostic tools.
• Current methods for bacterial detection in urine can be time-consuming or lack specificity.
• Low-concentration bacterial detection in complex matrices like urine is challenging.

Purpose of the Study:

• To develop and validate a novel biosensor for the selective detection of Gram-negative and Gram-positive bacteria in human urine.
• To assess the biosensor's sensitivity at clinically relevant bacterial concentrations.
• To evaluate the biosensor's performance in the presence of interfering urinary constituents.

Main Methods:

• Utilized long-range surface plasmon polariton (LR-SPP) waveguides as the sensing platform.
• Tested the biosensor with human urine samples spiked with known concentrations of bacteria.
• Employed a negative control urine solution with a high concentration of non-target substances to assess selectivity.
• Measured signal ratios to quantify bacterial detection.

Main Results:

• The LR-SPP waveguide biosensor demonstrated selective detection of both Gram-negative and Gram-positive bacteria.
• Achieved detection limits of 10^5 CFU/ml, aligning with the diagnostic threshold for UTIs.
• Obtained a positive-to-negative signal ratio of 5.4 in the presence of a 1000x higher concentration of interfering substances.

Conclusions:

• Long-range surface plasmon polariton waveguides are effective biosensors for bacterial detection in human urine.
• The developed biosensor offers high sensitivity and selectivity for diagnosing UTIs.
• This technology holds promise for rapid and accurate point-of-care diagnostics.