In-situ rapid bioaerosol detection in the ambient air by miniature multiplex PCR utilizing technique

Given the current problems associated with the COVID-19 pandemic, research in the field of rapid and reliable detection and characterization of airborne pathogenic microorganisms is becoming of exceptional urgency. This project is focused on development of portable first alert bioaerosol monitoring technique utilizing personal bioaerosol sampler capable of high efficient trapping of airborne microorganisms into collecting liquid along with a laser based mini Polymerase Chain Reaction (PCR) machine in a multiplex format (multi-target simultaneous detection) with following identification of minimal time period required for detection of any airborne microbial targets in the ambient air. The experimental program was undertaken under controlled laboratory conditions utilizing of up to 7 plex PCR format for detection of airborne microbial targets in the dynamic aerosol chamber. The technology demonstrated efficient operation and was capable of detecting airborne microbial targets during even shortest experimental sampling periods of 10 s. The total time of detection/analysis was less than 40 min. The proposed sampling timeframe represents realistic scenario of bioaerosol exposure of humans’ moving through areas potentially contaminated by bioaerosol originated from natural or anthropogenic sources. The research outcomes look very promising enabling development of new generation of portable, reliable and fast bioaerosol monitors, which are unique and highly demanded in the areas of defence, public health and others

New personal sampler for viable airborne viruses: feasibility study

While various sampling methods exist for collecting and enumerating airborne bacteria and fungi, no credible methodology has yet been developed for airborne viruses. A new sampling method for monitoring the personal exposure to bioaerosol particles has recently been developed and evaluated with bacteria and fungi. In this method, bacterial/fungal aerosol is aspirated and transported through a porous medium, which is submerged into a liquid layer. As the air is split into numerous bubbles, the particles are scavenged by these bubbles and effectively removed. The current feasibility study was initiated to evaluate the efficiency of the new personal sampler prototype ("bubbler") with airborne viable viruses. Two common viral strains, Influenza (stress-sensitive) and Vaccinia (robust), were aerosolized in the test chamber and collected by two identical "bubblers" that operated simultaneously for a duration of upto 5 min. A virus maintenance liquid, proven to be the optimum collecting environment for the test organisms, was used as a collection fluid. After sampling, the collecting fluid was analyzed and the viral recovery rate was determined. The overall recovery (affected not only by the sampling but also by the aerosolization and the aerosol transport) was 20% for Influenza virus and 89% for Vaccinia virus. The new sampling method was found feasible for the collection and enumeration of robust airborne viruses

Personal sampler for viable airborne microorganisms: Main development stages

A new personal bioaerosol sampler has been developed and verified as an efficient tool for monitoring of viable/non-viable airborne microorganisms, including bacteria, fungi, and viruses. The operational principle of the device is based on continuous passage of an air sample through porous media submerged into a liquid layer. During motion along narrow and tortuous ways inside the porous media, the air stream is split into a large number of ultra small bubbles with the particulates are being scavenged by these bubbles and, thus, effectively trapped. The device was initially verified for monitoring of viable airborne bacteria and fungi, firstly, under controlled laboratory conditions and later in a field. It was demonstrated that bacterial recovery rates for these two groups of microorganisms were very high and the device was found to be fully feasible for such monitoring. The next step of the device investigation was performed in the laboratory on monitoring viable airborne viruses with a range of sensitivities to physical and biological stresses. As the result, the new personal sampler demonstrated a very high recovery rate even for viruses which are rather sensitive to environmental stress (Avian Influenza, SARS, Mumps, etc.). Some following field studies, undertook in a hospital and animal houses, also demonstrated an excellent performance of the new device for selective and reliable monitoring of viable airborne viruses even in environments highly contaminated by other microorganisms. This paper reviews the main development staged of the new personal bioaerosol sampler

A new thermophoretic precipitator for off-line particle analysis

A new thermophoretic particle precipitator has been developed for representative and efficient collection of aerosol particles from the ambient air and technological pipelines. The device consists of hot and cold plates (5×5cm) capable of operation at temperature gradients ranging from 20000 to 100000K/m. A gas sample is made to pass through a 1-mm slot between the plates at a flow rate of up to 1.5L/min, which makes the device suitable for operation in conjunction with common aerosol instruments including DMA and diffusion batteries with similar operational flow rates. It was shown that the efficiency of the device was highest for the lowest gas flow rate used (0.3L/min) reaching a level of above 99%. The efficiency was decreased reaching its minimal values at the highest flow rate investigated (1.5L/min). However, even for highest flow rate, the average efficiency for removal of particle smaller than 60nm was around 50%

Thermophoretic coating with molybdenum oxide nanoparticles

Thermophoretic and electrophoretic coatings are the main viable mechanisms for the coating of objects with nanoparticles. Unlike electrophoretic coating, thermophoretic coating has the advantage that electrically conductive substrates are not a requirement. This paper investigates the thermophoretic deposition and uniformity of molybdenum oxide nanoparticles, generated by a glowing wire generator, on various surfaces at three different flow rates (0.3, 1 and 1.5Lmin). The quantitative evidence of the presence of particles collected by a suggested thermophoretic precipitator at different flow rates has shown that a uniform distribution of the particles could be achieved across the whole area of the precipitator. SEM and TEM micrographs of the film confirmed that a homogeneous densely packed network of molybdenum oxide nanoparticles was built across the precipitation area at the flow rate of 1.5Lmin

Contribution of Fine Particles to Air Emission at Different Phases of Biomass Burning

Particle size distribution in biomass smoke was observed for different burning phases, including flaming and smouldering, during the combustion of nine common Australian vegetation representatives. Smoke particles generated during the smouldering phase of combustions were found to be coarser as compared to flaming aerosols for all hard species. In contrast, for leafy species, this trend was inversed. In addition, the combustion process was investigated over the entire duration of burning by acquiring data with one second time resolution for all nine species. Particles were separately characterised in two categories: fine particles with dominating diffusion properties measurable with diffusion-based instruments (Dp < 200 nm), and coarse particles with dominating inertia (Dp > 200 nm). It was found that fine particles contribute to more than 90 percent of the total fresh smoke particles for all investigated species

Control of Airborne Microorganisms by Essential Oils Released by VaxiPod

Currently, due to the global pandemic caused by severe acute respiratory syndrome coronavirus SARS-CoV-2, new procedures and devices for effective disinfection of indoor air are of obvious interest. Various studies demonstrated quite broad ranges of the efficiency of essential oils in the control of biological aerosols. This project reports the results of investigation of the antimicrobial activity of essential oils natural for Australia (tea tree oil, eucalyptus oil and lemon myrtle) distributed by newly developed VaxiPod device for various scenarios, including bacterial, viral and fungal inactivation on various surfaces and in aerosol form. It was found that the device was capable of operating continuously over 24-h periods, providing sufficient aerosol concentration to efficiently inactivate microorganisms both on the surface and in airborne form. Twenty-four to forty-eight hours were required to achieve inactivation above 90% of most of the tested microbes on solid surfaces (stainless steel discs and agar plates), whilst similar efficiency of inactivation on fibrous filter surface as well as in aerosol form was achieved over 30–60 min of the process run. The results look very promising for further development of bioaerosol inactivating procedures and technologies for air quality control applications