Isolation of pathogenic bacteria from sputum samples using a 3D-printed cartridge system

Area of Science:

• Biomedical Engineering
• Microfluidics
• Molecular Diagnostics

Background:

• Sputum sample preparation for Polymerase Chain Reaction (PCR) is critical for diagnosing respiratory infections.
• Current methods can be costly, time-consuming, and prone to contamination.
• There is a need for efficient, cost-effective, and user-friendly sample preparation systems.

Purpose of the Study:

• To develop and evaluate a 3D-printed cartridge system for streamlined sputum sample preparation.
• To enable convenient and cost-efficient sample processing for subsequent PCR-based detection.
• To ensure the integrity and viability of bacterial cells for diverse downstream analyses.

Main Methods:

• Design and fabrication of a 3D-printed microfluidic cartridge system.
• Utilizing pneumatic actuations for fluidic control within a closed system.
• Employing amine-functionalized expanded glass beads for bacterial cell enrichment.
• Comparing the performance of expanded glass beads with magnetic particles.
• Testing the system with artificial and real sputum samples spiked with *Escherichia coli* and *Moraxella catarrhalis*.

Main Results:

• The 3D-printed cartridge system demonstrated convenient and cost-efficient sputum sample preparation.
• The closed system minimized contamination risk during sample processing.
• Expanded glass beads outperformed magnetic particles, yielding intact and viable bacterial cells.
• Larger channel dimensions with glass beads reduced hydrodynamic resistance for viscous sputum.
• The system successfully processed artificial and real sputum samples.

Conclusions:

• The developed 3D-printed cartridge offers a robust solution for sputum sample preparation.
• The system supports sensitive detection methods like PCR and preserves cell viability for other assays.
• Expanded glass beads are a superior choice for particle-based enrichment in this microfluidic system.
• This technology has the potential to improve the accessibility and efficiency of respiratory pathogen diagnostics.