3-D printed polyvinyl alcohol matrix for detection of airborne pathogens in respiratory bacterial infections

Novel sampling matrices were manufactured using 3D printing for the detection of respiratory pathogens in expired air. A specific configuration of the matrices was designed using Computer-Aided Design software. Polyvinyl alcohol (PVA) was printed using fused deposition modelling to create a multilayer matrix to enhance the capture of bacteria. The performance of these matrices was compared with gelatine filters that have been used for this work to date. PVA matrices (60 mm diameter) were contaminated with bacteria either by direct inoculation, or by aerosol exposure using an Omron A3 nebuliser. Rough and smooth morphotypes of Mycobacterium abscessus, M. smegmatis and M. bovis BCG, were used in this study to contaminate the matrices. PVA matrices and gelatine sampling filters were contaminated to compare recovery rates for quantitative analyses. These were dissolved in water, bacteria pelleted and DNA extracted followed by a Mycobacterium-specific quantitative Polymerase Chain Reaction (qPCR).The results showed that 3D printed PVA matrices are very effective to capture the bacteria. 3D printed PVA matrix and gelatine filters yielded results of the same order of magnitude for mycobacterial analyses, however, PVA matrix offers several advantages over the latter material. 3D printed PVA is considered as an economic and time-effective matrix as it is cheaper than gelatine filters. PVA is sufficiently robust to be handled and loaded into the surgical masks for sampling, compared to the brittle gelatine filters that required supportive frames. PVA is a synthetic material and it is suitable for DNA-based analyses, whilst gelatine is derived from animal collagen, and carries a high bacterial DNA background that interferes with the target DNA analysis. Furthermore, PVA dissolves in distilled water without requiring chemicals or enzymes, such as the case for gelatine hydrolysis. To summarise, 3D printed PVA sampling matrix is considered a promising tool used for microbiological diagnostic purposes.