On-Chip Optical Nano-Tweezers for Culture-Less Fast Bacterial Viability Assessment.

Area of Science:

• Biomedical Engineering
• Microbiology
• Optical Physics

Background:

• Antibiotic misuse fuels the rise of antibiotic resistance, a significant global health concern.
• Current culture-based bacterial tests are slow (1-2 days), necessitating broad-spectrum antibiotic use before pathogen identification.
• Rapid diagnostics are crucial for timely and effective antimicrobial therapy.

Purpose of the Study:

• To develop a novel, rapid, culture-less method for assessing bacterial viability and response to stress.
• To demonstrate a proof-of-concept using optical tweezing for single-cell bacterial analysis.

Main Methods:

• Utilizing on-chip optical tweezing with a laser-loaded nanobeam cavity to trap individual bacteria.
• Measuring shifts in optical resonance caused by the bacterium's optical index, correlated with cell wall changes.
• Applying thermal stress (45°C, 51°C, 70°C) to bacteria and analyzing viability via optical index shifts.

Main Results:

• The optical index changes of bacteria directly correlated with the level of thermal stress.
• The method successfully differentiated between viable and non-viable bacteria based on optical properties.
• Bacterial viability was assessed in under 4 hours, significantly faster than traditional 24-hour culture methods.

Conclusions:

• This culture-less optical tweezing approach offers a disruptive, rapid diagnostic tool for bacterial viability.
• The technology enables single-cell analysis, providing faster insights into bacterial response to stress.
• Accelerated diagnosis can lead to more precise and timely therapeutic interventions, combating antibiotic resistance.