Using Space-Charge Electret Products for Contamination Control

Jianliang Gong- C-POLAR Technologies, Inc., Hong Kong

Chun Yin Or- C-POLAR Technologies, Inc., Hong Kong

Jeanne Moldenhauer- C-POLAR Technologies, Inc., Lake Villa, IL

Introduction

Recently, the European Union released a revision to the Good Manufacturing Practices (GMP) Annex 1, which provides the rules for the manufacture of sterile drug products. It took 14 years of development to make this revision. The revised requirements, which are set to take effect 25 August 2023, govern the manufacturing of sterile drugs made in the EU, as well as imported products. An interesting addition to this document is while the Annex 1 is intended to provide guidance for the manufacture of sterile products, it has wording that says, “some of the principles and guidance, such as contamination control strategy, design of premises, cleanroom classification, qualification, validation, monitoring and personnel gowning, may be used to support the manufacture of other products that are not intended to be sterile such as certain liquids, creams, ointments and low bioburden biological intermediates, but where the control and reduction of microbial, particulate and endotoxin/pyrogen contamination is considered important.” (Eglovitch, 2022)

With the increased regulatory scrutiny on contamination control, prevention of contamination provides the most cost-effective means of dealing with this issue. Waiting until one has a contamination event can result in the need to perform an investigation, additional testing, and delay of releasing the batch of product or actual loss of the production batch.

While there are numerous sanitization, disinfection, and sterilization products available, excessive use can result in high costs, corrosion on surfaces, and increased labor costs. Today there are newer methods based upon physics which can allow for low-cost prevention methods that may be superior to chemical disinfection methods. This paper discusses the use of a space-charge electret product for contamination control of environments.

What is a Space-Charge Electret?

To explain this phenomenon the terms will be broken down into several pieces. An electret is a polarized piece of dielectric material. It is like a permanent magnet. Like a magnet, it can have positive poles or negative poles (polarity). When one is considering viral or microbiological inactivation, one would want an electret that is positively charged. The reason for this is that both microorganisms and viruses are negatively charged. Like a magnet, the positively charged electret will attract the negatively charged microorganisms and viruses.

Various types of materials can be used as the electret material, e.g., non-woven fibers, spunlace, filtration materials, and so on. The materials are electrostatically charged to give the desired type of charge (i.e., positive, or negative charges).

An electrical field is the area that surrounds the electrically charged particles. It exerts force on the other charged particles in the same field. They are either attracted or repelled depending upon their charge. Opposite charges attract. Identical charges repel. In Figure 1, the positive particle is shown sending out an electrical charge (arrows point outward) and the negative particle is shown drawing in an electrical charge (arrows point inward).

It is common in physics to visualize the electric field (space charge) by using field lines. The field lines initiate on the positive charge and terminate on the negative charge. The field lines are parallel to the direction of the field. The density of the field lines is based upon the measurement of the magnitude of the electric field at a given point. Each single electron and single proton have the same amount of charge. (Sir, 2022)

Figure 2 is another way of showing the electron cloud, where the electrons are surrounding the nucleus, and the cloud (the whole area where the electrons travel) is based upon where the electrons are at any point in time.

Whenever there are more of either protons or electrons in the electrical field, the electrons in the surrounding area move to balance out the extra protons. Regardless of the type of field, the electrons are always the moving parts, as the protons are stationary. (Sir, 2022)

How Does Microbial Death and Viral Inactivation Occur?

There are many natural examples of electrostatic phenomena like how plastic wrap clings to your hand when it is removed from the package or what seems like a spontaneous explosion of grain silos. (Sir, 2022) Electrostatics can also be utilized to kill microorganisms and inactivate viruses.

One such use has been in the area of antimicrobial and antiviral face masks. (Tsai, 2020) Tsai was responsible for the invention of the N95 Mask Filter. He created a layer of the filter that includes both positive and negative charges, stopping the contaminants from passing through the mask. (Andrew, 2020)

Under specified conditions, the microorganisms and viruses are attracted to the space-charge (electric field). When the negatively charged microorganism or virus comes into contact with the positive charge, the microorganism is electrocuted (killed). Viruses become inactivated. (Personal Communication, 2022).

Applications of Space-Charge Electrets Usage for Contamination Control

There are numerous ways that space-charge electrets can be utilized to aid in contamination control. As previously discussed, this type of technology has been applied to masks and respirators. However, consider the use of gowning and uniforms that include antimicrobial and antiviral properties. Early in pharmaceutical training we learn that people are the major source of contamination in clean rooms. Regardless of the company, most contamination investigations result in citing personnel being the source of the contamination. Many cleanroom garments are not easy to put on and maintain the sterility of the gowning. The leg portions accidentally touch the floor or bench during donning. Sleeves or arm portions of the gowning can get wet, allowing for microbial transfer from the inside of the uniform out into the environment today. Use of an antimicrobial and antiviral layer in the uniform could trap and kill or inactivate the contaminants.

Another possibility is the use of antimicrobial and antiviral treatments on non-latex gloves to yield the same protection as a latex glove. This would reduce the likelihood of developing allergies to latex gloves. Granted, some may choose to use isolators to protect the product from exposure to humans, but there are opportunities to protect our environments. However, the isolator glove still has become a common source of contamination. Use of a space-charge electret with antimicrobial and antiviral properties would eliminate or significantly reduce the likelihood of contamination from these sources.

Typical cleanrooms utilize HEPA filtered air but consider the benefit of using an antimicrobial and antiviral filter. This could be implemented in a pre- or post-filter to prevent contamination from entering the environment from the air system.

Cleanroom curtains can be a source of contamination, due to the difficulties in properly cleaning and disinfecting them. This could be replaced by a treated curtain that is “self-sterilizing” due to its antimicrobial and antiviral properties.

We often think of contamination control, primarily applying to clean rooms, but office areas and supporting areas can also influence our production of products. A study of the effects of contamination in new buildings and hospitals was conducted in 2015. In this report, it states “SBS (sick building syndrome), which impacts up to 30% of new buildings according to the World Health Organization.” Furthermore, this report indicates that “SBS causes a decrease of productivity, increased absenteeism, as well as the costs to fi x it to companies.” (Avaltroni, et al., 2015) The recent pandemic reminded us of the many issues associated with sick employees and the likelihood of them contaminating other employees. The use of antimicrobial and antiviral air filters in the routine HVAC systems could substantially reduce the likelihood of transmission from employee to employee of airborne organisms and viruses.

Avaltroni, et al. (2015) also indicated that the sick building syndrome is more common in new or recently remodeled buildings. Contributing factors include less air flow, newly installed office furnishings, newly painted walls, building materials and furnishings. This report also states, “in 1984 the World Health Organization (WHO) estimated that up to 30% of new buildings and recently renovated building are subject to excess complaints about poor indoor air quality.” An antimicrobial and antiviral space-charge electret has been evaluated on many types of fabrics, which could be utilized with many different types of office furnishing. Included in this assessment could be the use of these filters to reduce the microbial and viral counts in the air system.

Since space-charge electrets have been used on a variety of textiles, consider use of the paper/fabrics used to wrap components prior to sterilization to maintain sterility prior to use.

Another potential use is for the paints and wall coverings used in the facility.

The list of applications of this technology is mind-boggling.

Other Considerations When Considering Electrets for Your Process

While the list of applications is extensive, one should evaluate the space[1]charge electrets available to determine the appropriate methodology.

The method of creating the charged surface can be expensive for some types of systems, e.g., use of positively charged metal ions. It is important to understand whether other capital equipment is required to use the antimicrobial antiviral system. Ideal systems do not require specialized capital equipment be used with the treated surface. For example, if it is used for air filtration an ideal system would only require the use of an air filter in the existing HVAC system.

For disposable gowning, one needs to consider the disposal of the used gowning. Ideally, having a treated gown that is biodegradable has significant benefits to the environment.

Many of the space-charge electrets are made using polymers. It is important to know about the polymer. For example, are there safety concerns? Are there disposal concerns? What is the stability of the polymer? Will it be affected by washing?

Will the charged surface degrade over time? If so, what is the appropriate time period (expiry) for use?

Depending upon the process utilized, there may be other considerations for use.

Conclusion

Using a space-charge electret can be very useful in reducing the risks of contamination. One benefit of these systems is that being based upon physics, it is impossible to develop a resistance to the kill or inactivation of the contaminants. With sufficient use, we can develop contamination control procedures that are economical and may also benefit us with reducing routine health issues with employees.

Literature Cited

1. Andrew, S. (2020) He invented the N95 Mask Filter. Then the Coronavirus hit and he was called to help once again. CNNHealth. Downloaded from: Peter Tsai, inventor of the N95 mask filter, is on a mission to help healthcare workers - CNN on September 9, 2022.
2. Avaltroni, R., Constantinides, C., Dipaolo, G., Fields, R., Gallo, L., Glorie, D., Haitoff, J., Holzka, D., Napolitano, M., Nastasi, J., Pirovolikos, S., Robinson, K., Shilling, S., Singh, U., Tobin, R., Emanuelli, J. and Finan, E. (2015) Indoor Air Quality and Sick Building Syndrome in Health Care Facilities and Commercial Buildings. Downloaded from: EAC-whitepaper.pdf (environmentaladvisorycouncil.org) on September 8, 2022.
3. Eglovitch, J.S. (2022) EU issue long-awaited GMP Annex 1 revision. Regulatory News. Downloaded from: EU issues long-awaited GMP Annex 1 revision | RAPS on September 7, 2022.
4. Electric Field Image (2022) downloaded from: image electric field - Bing images on September 7, 2022.
5. Electron Cloud Image downloaded from: image electron cloud - Bing images on September 7, 2022.
6. Personal Communication (2022) Data generated for C-POLAR Technologies, Inc.
7. Sir, M. (2022) Electrostatics. BYJU’s. Downloaded from: Electrostatics (Coulomb’s Law of Electrostatics) - Definition, Example, Formula (byjus.com) on September 8, 2022.
8. Tsai, P. (2020) Performance of Masks and Discussion of the Inactivation of SARS-CoV-2. Engineered Science. Downloaded from: Performance of Masks and Discussion of the Inactivation of SARS-CoV-2 (espublisher.com) On September 9, 2020

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