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EM contributes to local production of PPE
Author: Jurgen Kriel
Published: 28/08/2020
​​One of the main reasons for the strict lockdown regulations in South Africa during COVID-19, was to prevent overcrowding of hospitals and provide them with precious time to prepare for the expected influx of patients as transmissions peaked. Over time, it became apparent that this preparation mainly centred around one critical element – the procurement of personal protective equipment (PPE). In light of these events, the Electron Microscopy (EM) Unit is currently providing critical EM analytical support to the Stellenbosch Nanofiber Company (SNC), which is in the process of manufacturing reusable filters for face masks.  


One of the filter layers (which is part of medical-grade face masks) before the SEM analysis.​​
An image of a SEM analysis of the filter.
Continuous provision of PPE to health care workers (HCWs) is of paramount importance in the fight against the COVID-19 pandemic. PPE constitutes a range of products including gloves, face shields, surgical gowns and face masks. HCWs come into contact with multiple patients per day and therefore require certified equipment to serve as an effective barrier between them and their patients. Therefore, PPE can be regarded as the barrier that not only prevents HCWs from becoming carriers of the novel coronavirus but also prevents hospitals themselves from becoming transmission ‘hotspots’, which can result in the closing of hospitals. Sadly, as a result of increased global demand, many countries are struggling to provide frontline HCWs with adequate PPE and South Africa is no exception. 

In response to these shortages, many local manufacturers have repurposed their production lines to manufacture various forms of PPE for general public use. The difficulty with mass producing medical-grade PPE is that manufacturers must adhere to the strict International Organization for Standardization guidelines as well as be certified by government to produce medical equipment. 

SNC is a prime example of a company specialising in the commercial-scale manufacturing of advanced biomedical nanofiber materials. Nanofiber materials have extremely versatile biomedical applications, encompassing wound dressing, drug release materials and cell culture scaffolds. In response to the growing demand for PPE, SNC is currently working on the production of the most important part of medical-grade face masks, namely the filter layer.  What is unique about SNC’s filter layers is that they physically entrap and immobilise viral particles as opposed to conventional melt-blown polypropylene layers that electrostatically trap particles. This might seem like a small difference, but it allows for the nanofiber-based filters to be washed and reused, whereas the electrostatic properties of the polypropylene-based filters diminish with each wash. 

In order to confirm whether these filter layers are capable of entrapping nanoscale particulates and to assess how robust these nanofibers are, scanning electron microscopy (SEM) analysis is required to measure the distance between fibres as well as the fibre size. This makes SEM analysis integral to the production of nanofiber-based filter layers. 

The ThermoFischer Apreo VolumeScope scanning electron microscope is the newest addition to the CAF Electron Microscopy Unit and has been instrumental in assisting SNC to perform this much-required analysis. Although the main purpose of the Apreo is to function as a serial block-face microscope, capable of acquiring 3D volumetric EM datasets, it is also a very capable scanning electron microscope for general image acquisition, which makes it an extremely versatile tool. 

The procurement of the Apreo was accompanied by the appointment of a new CAF staff member, Mr Jurgen Kriel. Currently finishing his PhD in Physiological Sciences at Stellenbosch University, Kriel was appointed in March 2020 to provide SEM analytical services to medical researchers on Tygerberg Campus. Although the national lockdown has put a hold on many research projects, the Apreo continued running to provide industry clients such as SNC with essential analytical services. However, these services are not provided without risk. Being near Tygerberg Hospital has its inherent dangers in a time when Tygerberg has the highest number of confirmed COVID-19 cases in the Western Cape (at the time of writing this article). 

Safety guidelines are of paramount importance, not only for the safety of employees but also for that of their families. “It was quite a difficult decision to go back to work. Right before the Level 5 lockdown was imposed, my mother started with chemotherapy. As much as I wanted to help SNC, I also did not want to place my family in harm’s way. My manager, Ms Madelaine Frazenburg, was very understanding and left the decision up to me. Having a vulnerable family member really puts the importance of adhering to the safety guidelines into perspective. After I decided to help SNC, I was very relieved to see how well everyone on Tygerberg Campus adhered to these guidelines” Kriel said.

Until a vaccine is developed, the demand for appropriate PPE will remain high. Being able to reuse medical-grade face masks will alleviate the financial burden on hospitals significantly. “Various tests are ongoing to demonstrate the robustness of the filters, but initial tests have already shown that we maintain filtration efficiency even after 10 cycles of submersion in boiling water for 10 minutes and air drying”  Dr Megan Coates, Research and Development Manager at SNC said.  SNC is currently in the process of building partnerships for further production of face masks once testing on the filters has been completed. 

(As published in the CAF Annual Report)