A NASBA on microgel-tethered molecular-beacon microarray for real-time microbial molecular diagnostics

Area of Science:

• Biotechnology
• Molecular Diagnostics
• Microarray Technology

Background:

• Molecular beacon (MB) hybridization probes offer advantages but face challenges in microarray formats due to probe-substrate interactions increasing background noise.
• Previous work demonstrated tethering MB probes to surface-patterned microgels effectively localizes probes and minimizes surface interactions in a microarray setting.
• This study extends the microgel-tethered MB probe approach to incorporate real-time detection and integrated nucleic acid sequence-based amplification (NASBA).

Purpose of the Study:

• To develop and validate a novel microarray-based molecular diagnostic platform for detecting pathogens in bloodstream infections.
• To integrate real-time detection and isothermal amplification (NASBA) with microgel-tethered molecular beacon probes.
• To assess the sensitivity and specificity of the developed platform for detecting bacterial and fungal RNA targets.

Main Methods:

• Fabrication of small microarray assays (simplex, duplex, five-plex) with controllable spot characteristics using microgel-tethered molecular beacon probes.
• Integration of targets, primers, and probes in a single isothermal reaction chamber for nucleic acid sequence-based amplification (NASBA) and real-time detection.
• Extraction of total RNA from clinical blood samples for pathogen detection and differentiation.

Main Results:

• Demonstrated successful detection of bacteria and fungi in a bloodstream infection model using multiplexed assays.
• Achieved real-time detection without post-amplification labeling, differentiating Gram-positive and Gram-negative infections.
• Reported a sensitivity of tens of bacteria per ml for specific ribosomal RNA sequences in a simplex assay.
• Showcased 1 fM sensitivity for detecting synthetic target DNA amplicons in small sample volumes.

Conclusions:

• The microgel-tethered molecular beacon microarray platform offers a promising alternative for rapid, real-time molecular diagnostics.
• This approach effectively overcomes limitations of traditional microarray probe-substrate interactions, enabling sensitive pathogen detection.
• The integrated NASBA and real-time detection capabilities facilitate efficient analysis of clinical samples for bloodstream infections.