Bacterial Filtration Efficiency Research Articles

Evaluation of the penetration capacity of bacteria through layers of different face mask types and wearing conditions.

The aim of this study was to quantify the number of non-airborne bacteria that can passively penetrate the layers of four mask types (surgical mask, community face mask type 1 (CFM1), biocidal CFM1 and CFM2) and to determine the influence of wearing conditions for the surgical type. A mask wearer simulator consisting of a 3D anatomical replica of the upper airway connected to a breathing pump was used. Wearing time, filtration quality of the mask, fit (loose vs. tight) and breathing parameters (tidal volume, respiratory rate) were tested. A Staphylococcus epidermidis inoculum was applied to the inner layer. After the wearing simulation, the layers were separated and the bacteria counted. After four hours, no or only a few bacteria were present in the middle and outer layers. Most remained in the inner layer. Surgical mask and CFM1 retained more bacteria and provided a breeding ground for germs. The biocidal CFM1 rapidly reduced the number in the inner layer. The breathing parameters had no influence, in contrast to fit and wearing time. These results confirm that the standard test for bacterial filtration efficiency, which includes the active penetration of airborne bacteria into aerosol droplets, is the most objective measure of the ability of bacteria to penetrate through the mask layers, as the passive penetration ability of non-airborne bacteria is insignificant.

Negative Voltage Electrospinning for the Production of Highly Efficient PVDF Filters

AbstractIn recent years, the demand for filter media has increased dramatically, driven by the need to manufacture personal protective equipment and for various applications in the industrial and civil sectors. Nanofiber‐based membranes are proposed as potential alternatives to commercial filtration devices. This study presents the design and implementation of an innovative pre‐industrial electrospinning setup, combining a negatively charged spinneret and a positively charged counter‐electrode, capable of producing polyvinylidene fluoride (PVDF) nanofibers with an average diameter of 410 nm and electrostatic surface potential values 3.7 times higher compared to a conventional electrospinning process, eliminating the need for further post‐treatment. These properties are essential for improving mechanical and electrostatic filtration of small particles, including infectious droplets. The surface potential of the membranes is also long‐lasting, as evidenced by tests one year after manufacture. As a case‐study, these filters are used to manufacture surgical masks, reporting excellent performance in terms of bacterial filtration efficiency (BFE) up to 99.9%, and breathability (29.8±4.5 Pa cm−2) when compared to commercially available meltblown polypropylene (PP) face masks, and also complied with the stringent European standard (EN14683:2019) for type‐II surgical masks. Furthermore, the pre‐industrial setup allows for increased production capacity of up to 42 000 m2 per year, suitable for large‐scale production.

Bacterial Filtration Efficiency

Bacterial Filtration Efficiency

Development of highly bacterial filtration efficient and antibacterial cellulose acetate/gum rosin composite nanofibers for facemask application

Cellulose acetate (CA) is a non-toxic, renewable, and biodegradable polymeric material that can be effectively electrospuned into bacterial filtration efficient nanofiber membrane for face mask application. However, its fragile and non-antibacterial nature influenced its scalability. In this context, natural antibacterial gum rosin (GR) additive can be explored. Therefore, the present study aimed to produce a CA/GR composite nanofibers membrane for the finest bacterial filtration, excellent antibacterial moiety, and improved tensile properties for facemask application. Hence, in this work, we have studied the effect of GR concentrations (0–15 g) on the needleless electrospinning behavior and fibers' morphology through rheology, electrical conductivity, and SEM analysis. These analyses revealed that GR significantly affects the fibers' spinning behavior, morphology, and diameter of the produced fibers. Later, ATR-FTIR spectroscopy mapped the functional changes in the produced nanofibers that affirmed the integration of GR with CA polymer. This modification resulted in a 3-fold rise in tensile strength and an 11-fold decline in elongation% in 15 g CA/GR composite nanofibers membrane than the control sample. Furthermore, it has shown 98.79 ± 0.10% bacterial filtration efficiency and ∼ 93 % reduction in Staphylococcus Aureus and Klebsiella Pneumoniae bacterial growth, elucidating a high-efficiency level for potential facemask application.

Riboflavin based setup as an alternative method for a preliminary screening of face mask filtration efficiency

Face masks are essential in reducing the transmission of respiratory infections and bacterial filtration efficiency, a key parameter of mask performances, requires the use of Staphylococcus aureus and specialised staff. This study aims to develop a novel method for a preliminary screening of masks or materials filtration efficiency by a green, easy and rapid setup based on the use of a riboflavin solution, a safe autofluorescent biomolecule. The proposed setup is composed of a commercial aerosol generator commonly used for aerosol therapy, custom 3D printed aerosol chamber and sample holder, a filter for downstream riboflavin detection and a vacuum pump. The filtration efficiency of four different masks was assessed using the riboflavin-based setup and the bacterial filtration efficiency (BFE). The averaged filtration efficiency values, measured with both methods, were similar but were higher for the riboflavin-based setup (about 2% for all tested samples) than bacterial filtration efficiency. Considering the good correlation, the riboflavin-based setup can be considered validated as an alternative method to bacterial filtration efficiency for masks and related materials fabrics filtration efficiency screening but This study aims to develop a novel method for a preliminary screening of masks or materials filtration efficiency by a green, easy and rapid setup based on the use of a riboflavin solution, a safe autofluorescent biomolecule, but not to replace regulation approaches. The proposed setup can be easily implemented at low price, is more rapid and eco-friendly and can be performed in chemical-physical laboratories without the needing of biosafety laboratory and specialised operators.

A study on multi-layered surgical masks performance: permeability, filtration efficiency and breathability

Surgical masks have been widely used in the past for protection purposes against infection as a hygiene product. Masks, which are often used by healthcare professionals, are also widely used by the general public during pandemic periods. Surgical masks were designed in various ways according to colour, nose strip, earloop, grams per square meter and several layers. Some performance features are expected from these masks according to certain standards. In this study, it has been studied on multi-layered surgical masks. Thickness, air permeability, bacterial filtration efficiency and differential pressure properties of these masks consisting of polypropylene spun bond and melt-blown layers were investigated. The effects of an increase in grams per square meter, the number of layers and the melt-blown layer on the mentioned properties were determined. As a result; it has been observed that the optimal mask is one of the 4-ply masks. Also, it has been concluded that increasing the number of layers does not always provide an increase in performance; instead, an increase in grams per square meter can meet the expectation. Therefore, it can be said that it is necessary to determine the appropriate weight in grams and the appropriate number of layers with suitable raw materials to provide the expected features from the surgical masks.

Comparison of in situ and padding method to incorporate Green synthesized AgNPs by using Calendula arvensis into nonwoven fabrics

Nonwoven fabrics are the primary source of disposable medical clothing, which cause a huge medical waste. One possible way to reuse this disposable clothing is through antibacterial treatment. Among various metal nanoparticles, silver nanoparticles (AgNPs) are preferable regarding ecology and human health. Green synthesis is an ecological alternative to synthesize AgNPs from silver nitrate (AgNO3) solution. The silver nanoparticles (AgNPs) were successfully synthesized from Calendula arvensis extract and AgNO3 at a certain temperature and incorporated into the fabric by padding and in-situ method. The pretreatments applied to the nonwoven fabric were found very important in terms of providing antibacterial activity. AgNPs applied according to the in situ method could provide 99% antibacterial activity on nonwoven surface fabrics. The samples treated by AgNPs with the in situ method performed better for both particle filtration efficiency (PFE) and bacterial filtration efficiency (BFE) than the samples treated with the padding method.

Engineering surgical face masks with photothermal and photodynamic plasmonic nanostructures for enhancing filtration and on-demand pathogen eradication.

The shortage of face masks and the lack of antipathogenic functions has been significant since the recent pandemic's inception. Moreover, the disposal of an enormous number of contaminated face masks not only carries a significant environmental impact but also escalates the risk of cross-contamination. This study proposes a strategy to upgrade available surgical masks into antibacterial masks with enhanced particle and bacterial filtration. Plasmonic nanoparticles can provide photodynamic and photothermal functionalities for surgical masks. For this purpose, gold nanorods act as on-demand agents to eliminate pathogens on the surface of the masks upon near-infrared light irradiation. Additionally, the modified masks are furnished with polymer electrospun nanofibrous layers. These electrospun layers can enhance the particle and bacterial filtration efficiency, not at the cost of the pressure drop of the mask. Consequently, fabricating these prototype masks could be a practical approach to upgrading the available masks to alleviate the environmental toll of disposable face masks.

Antimicrobial Personal Protection Clothing: Development of Visible Light Activated Antimicrobial Coatings for Nonwoven Polypropylene Fibers

AbstractDuring the COVID‐19 pandemic, the use of polypropylene fleece‐based personal protection equipment (PPE) increased significantly to over ten million tons. Typically, most PPEs are discarded after a single use, to prevent self‐infection of users and spread of infectious agents. However, in order to minimize plastic waste without compromising the protective properties of PPE, it is crucial to explore new reusable or longer‐lived materials. Here, a visible light‐activatable antimicrobial photodynamic dye coating for PPEs is presented. In this context, coating with thiomorpholino‐methylene blue (TMB), derived from methylene blue by introducing two thiomorpholine units, is found to show high antibacterial activity. TMB is integrated into rotary printing suspension, a commercial nitrocellulose‐based printing matrix. The concentration of TMB in adhesive is optimized, and found that 5% TMB is suitable for coating PPE, for reducing the number of Gram‐positive and ‐negative bacteria by 99.99% after 6 h of white light irradiation. Bacterial filtration efficiency and breathability tested according to EN 14683, confirmed that TMB coating does not affect the filter performance. Thus, this antimicrobial photodynamic dye coating technique offers a promising solution for a safer and extended use of PPE, and reduction of plastic waste generated by PPEs.

Highly breathable and durable waterproof polyimide electrospun nanofibrous membrane for potential reusable protective clothing application: Preparation, characterization and performance

The quest for a highly breathable protective clothing with good barrier performance is rapidly rising, especially in the fight against the COVID-19 pandemic. However, commercial protective clothing usually experiences trade-off between air permeability and barrier performance. Herein, a highly breathable and durable polyimide (PI)-based protective clothing material with good barrier performance was fabricated by electrospinning. The structure of PI electrospun nanofibrous membranes (PI-ENMs) was optimized in terms of mechanical strength, filtration efficiency and air permeability. The results showed that the PI-ENM with 500 nm diameter prepared by electrospinning for 4 h had high filtration efficiency (96.13 %), low pressure drop (57.1 Pa) and high-quality factor (0.057 Pa-1). The optimized PI-ENM had a high bacterial filtration efficiency of 99.48 %, which meant that it would possess good microbial barrier performance in practical applications. Due to the low air resistance, the PI-ENM demonstrated a high air permeability of 265.44 mm s−1, which was 40–160 times that of commercial protective clothing. An ultra-thin layer of polydimethylsiloxane (PDMS) was coated on the thermal stable PI-ENMs via chemical vapor deposition to obtain PI-ENM@PDMSs, of which the fire resistance was further enhanced without compromising filtration efficiency and resistance. Moreover, the PI-ENM@PDMSs exhibited strong hydrophobicity, robust mechanical strength, and excellent stability, and can be easily reused via common sterilization methods without impacting its protection performance. Therefore, PI-ENM@PDMSs is a promising candidate for reusable breathable protective clothing.

Staphylococcus epidermidis is a safer surrogate of Staphylococcus aureus in testing bacterial filtration efficiency of face masks

Face masks play a role in reducing the spread of airborne pathogens, providing that they have a good filtration performance, are correctly fitted and maintained. Bacterial Filtration Efficiency (BFE) is a key indicator for evaluating filtration performance according to both European and US standards, requiring the use of Staphylococcus aureus loaded aerosol. However, the generation and handling of a Biohazard group 2 bacterium aerosol require a careful management of the biological risk and pose limitations to the accessibility to this method. To mitigate these drawbacks, we investigated the use of S. epidermidis ATCC 12228, a Biohazard group 1 bacterium, as surrogate in BFE test. To this end, tests with the surrogate strain were performed to tune the method. Then, three face mask models, representative for both surgical and community masks, were tested according to the standard method and then using an aerosolized suspension of S. epidermidis. BFE% values were calculated for each mask model and tested microorganisms. Results showed that BFE test can be performed using the S. epidermidis instead of S. aureus, preserving results validity and turnaround time, but reducing residual risk for laboratory operators.

Harnessing the potential of regenerated bamboo knitted fabrics in development of eco-friendly masks

Purpose Face masks are the most recommended precautionary measure since the emergence of SARS-CoV-2 since 2020 and the most useful PPE against this virus and its variants so far. This study aims to develop reusable and biodegradable mask from 100% regenerated bamboo or/and its blend. Selection of natural and regenerated textile materials is to minimize generation of solid waste. This attempt will eventually protect our earth by minimizing or better discontinuing the production of the disposable nonbiodegradable face masks available worldwide. Design/methodology/approach Hundred percent regenerated bamboo and 50:50 bamboo:cotton were selected to knit plain and interlock fabrics for manufacturing of reusable sustainable face masks. A 23 32-mixed-level factorial design was applied to study the effect of liquor ratio and temperatures, fabric structure, blend ratios and finishes at three different levels. Model 23 32 has two factors (liquor ratio and temperatures) at three levels and three factors (fabric structure, blend ratios and type of finish) at two levels. Knitted fabrics were then applied with antibacterial finishes; sanitized T99-19 and sanitized T27-22, separately at three different liquor ratios (1:10, 1:12 and 1:15) and temperatures (45, 55 and 65 °C) via exhaust method. After completing processing, fabric thickness, pilling resistance, dimensional stability, bursting strength, Berger whiteness index, air permeability and antibacterial properties of each trial were evaluated using standard test procedures. Findings Selected fabrics treated either by sanitized T27 or sanitized T99 in a liquor ratio of 1:15 against 65 °C, showed excellent bacteriostatic/bactericidal activity. However, 100% regenerated bamboo interlock knitted fabric treated with sanitized T99 in a liquor ratio of 1:15 at 65 °C has the most desired values of dimensional stability, pilling resistance, Berger whiteness, fabric thickness, air permeability and bursting strength which made it the best for the manufacturing of the masks. Reusable mask is comprised of three layers in which the first and the third layers were of selected 100% regenerated bamboo fabric while a PM2.5 filter was inserted in between. Bacterial filtration efficiency, particle filtration efficiency, biocompatibility and microbial cleanliness will be evaluated in future, to compare the performance of proposed reusable and biodegradable face mask with N95 masks and other fabric masks available commercially. Originality/value This study resulted in a development of reusable eco-friendly facemask which was not attempted by the preceding investigations. Outcomes of this work pave the way for a greener and safer earth by using easily obtainable regenerated bamboo fabrics, antibacterial finishes and knitted structures.

Feasibility study of reusing surgical masks and evaluation of the effectiveness of different disinfection methods

This study assessed various disinfection methods' impact on surgical mask reusability amid the high demand and limited supply of medical surgical masks during the respiratory disease pandemic. Volunteers wore masks for 4 h, and masks were disinfected using methods including moist heat, dry heat, ultraviolet (UV) radiation, alcohol soaking, washing machine cleaning, ultrasonic cleaning, or microwave disinfection. Key indicators measured included filtration efficiency, mask pressure, electrostatic charge, tensile strength, and blood penetration. Scanning electron microscopy and 16S bacterial DNA testing were used to evaluate fiber changes and disinfection effectiveness. After three disinfection cycles using any method, masks met Chinese standard YY0469-2011 requirements for filtration efficiency, mask pressure, strength, and blood penetration. However, non-oily particle filtration efficiency significantly decreased with moist heat, alcohol soaking, or machine washing. Bacterial filtration efficiency decreased with dry heat, alcohol soaking, or machine washing. All disinfection methods caused structural changes, particularly with dry heat, ultrasonic cleaning, and microwave disinfection. UV radiation effectively sterilized masks while maintaining filtration performance, making it the preferred method for mask reuse in emergencies.

Multi-hierarchical nanofibre membranes composited with ordered structure/nano-spiderwebs for air filtration

To address environmental pollution and emerging infectious diseases, highly efficient filters capable of simultaneously removing air pollutants and pathogenic microorganisms must be developed. Traditional fibrous filter materials are incapable of effectively capturing fine particles owing to their wide fibres and large pores. In this study, we used electrospinning to combine nano-spiderwebs with an ordered nanofibre membrane and construct an air-filtration material with a multi-stage pore structure that filters efficiently to deliver breathable air. The prepared composite nanofibre membrane exhibited a filtration efficiency of > 98% for particulate matter < 0.3 µm in size with a pressure drop of < 100 Pa. The nano-spiderweb/ordered structure combination effectively improved the fine-particle filtration efficiency. In addition, the composite nanofibre membrane exhibited excellent bacterial filtration efficiency (>95%), highlighting its considerable potential for use in air-filtration applications.

The real bacterial filtration efficiency to evaluate the effective protection of facemasks used for the prevention of respiratory diseases

The real protection offered by facemasks to control the transmission of respiratory viruses is still undetermined. Most of the manufacturing regulations, as well as scientific studies, have focused on studying the filtration capacity of the fabrics from which they are made, ignoring the air that escapes through the facial misalignments, and which depends on the respiratory frequencies and volumes. The objective of this work was to define a Real Bacterial Filtration Efficiency for each type of facemask, considering the bacterial filtration efficiency of the manufacturers and the air that passes through them. Nine different facemasks were tested on a mannequin with three gas analyzers (measuring inlet, outlet, and leak volumes) inside a polymethylmethacrylate box. In addition, the differential pressure was measured to determine the resistance offered by the facemasks during the inhalation and exhalation processes. Air was introduced with a manual syringe for 180 s simulating inhalations and exhalations at rest, light, moderate and vigorous activities (10, 60, 80 and 120 L/min, respectively). Statistical analysis showed that practically half of the air entering to the system is not filtered by the facemasks in all intensities (p < 0.001, ηp2 = 0.971). They also showed that the hygienic facemasks filter more than 70% of the air, and their filtration does not depend on the simulated intensity, while the rest of the facemasks show an evidently different response, influenced by the amount of air mobilized. Therefore, the Real Bacterial Filtration Efficiency can be calculated as a modulation of the Bacterial Filtration Efficiencies that depends on the type of facemask. The real filtration capacity of the facemasks has been overestimated during last years since the filtration of the fabrics is not the real filtration when the facemask is worn.

A novel investigations on medical and non-medical mask performance with influence of marine waste microplastics (polypropylene)

The entire human race is struggling with the spread of COVID-19. Worldwide, the wearing of face masks is indispensable to prevent such spread. Despite numerous studies reporting on the fabrication of face masks and surgical masks to reduce spread and thus human deaths, this novel work is considered the marine waste of microplastics, namely Polypropylene (PP) polymer, used to fabricate non-woven fabric masks through the melt-blown process. This experimental work aims to maximize the mask's quality and minimize its fabrication cost by optimizing the melt-blown process parameters and using microplastics. The melt-blown process was used to make masks. Parameters such as extruder temperature, hot air temperature, melt flow rate, and die-to-collector distance (DCD) were investigated as independent variables. The quality of the mask was investigated in terms of bacterial filtration efficiency (BFE), particle filtration efficiency (PFE), and differential pressure. The Taguchi L16 orthogonal array and Taguchi analysis were employed for experimental design and statistical optimization, respectively. The results reveal that the higher BFE and PFE are recorded at 96.7 % and 98.6 %, respectively. The surface morphological investigation on different layers ensured the fine and uniform porosity of the layers and exhibited minimum breath resistance (a low differential pressure of 0.00152 kPa/cm2). Hence the chemically treated marine waste microplastics improved the masks' performance.

Betacoronavirus ve S. aureus'un hekzagonal bor nitrür ile etkileşimi

Investigations on advance effects of boron-containing compounds have gained attention the last decade. This study was carried out to investigate the effect of hexagonal boron nitride nanoparticles (BNNPs) on Bovine Coronavirus (BCoV) and Staphylococcus aureus (S. aureus) by different methods. First, biological effects of different BNNPs concentrations lower than 0.5 mg/mL examined on HRT-18 (Human Rectal Tumor) for 5 days. Different concentrations of hBN mixed with BCoV in liquid, on membrane or directly on cells and examined for differences of titers or replications. And also Bacterial Filtration Efficiency (BFE) test of hBN powders coated on polypropylene fabric by spray method was applied against S. aureus. The compound was found slightly toxic on the HRT-18 cell line by live cell counting, while no remarkable morphological difference was observed. BNNPs treatment with 0.025 or 0.3mg/mL concentrations did not reduce the infective titer and create no inhibitory effect on in vitro replication. Stability of virus titer after treatment of BNNPs coated fabric also indicated no antiviral efficiency. But hBN applied fabric formed a barrier of ≥90.3%, while non hBN applied fabric formed ≥64.6% barrier. The present study demonstrate that, BNNPs alone is not a good candidate for disinfectant or drug for BCoVs, while it could be valuable to use as coated fabric in the areas needing easy sanitation especially for S. aureus.

Filtration efficiency of medical and community face masks using viral and bacterial bioaerosols

Face masks are often recommended in community settings to prevent the airborne transmission of respiratory viruses or bacteria. Our first objective was to develop an experimental bench to assess the viral filtration efficiency (VFE) of a mask with a methodology similar to the normative measurement of bacterial filtration efficiency (BFE) used to determine the filtration performance of medical masks. Then, using three categories of masks of increasing filtration quality (two types of community masks and one type of medical mask), filtration performances measured ranged from 61.4 to 98.8% of BFE and from 65.5 to 99.2% of VFE. A strong correlation (r = 0.983) between bacterial and viral filtration efficiency was observed for all types of masks and for the same droplets size in the 2–3 µm range. This result confirms the relevance of the EN14189:2019 standard using bacterial bioaerosols to evaluate mask filtration, to also extrapolate mask performances whatever their filtration quality against viral bioaerosols. Indeed, it appears that the filtration efficiency of masks (for micrometer droplet sizes and low bioaerosol exposure times) depends mainly on the size of the airborne droplet, rather than on the size of the infectious agent contained in that droplet.

Biopolymer Coating Imparts Sustainable Self-Disinfecting and Antimicrobial Properties to Fabric: Translated to Protective Gears for the Pandemic and Beyond.

The global pandemic of COVID-19 and emerging antimicrobial drug resistance highlights the need for sustainable technology that enables more preparedness and active control measures. It is thus important to have a reliable solution to avert the present situations as well as preserve nature for habitable life in the future. One time use of PPE kits is promoting the accumulation of nondegradable waste, which may pose an unforeseen challenge in the future. We have developed a biocompatible, biodegradable, and nonirritating nanoemulsion coating for textiles. The study focused on coating cotton fabric to functionalize it with broad spectrum antimicrobial, antibiofilm, and anti-SARS-CoV-2 activity. The nanoemulsion comprises spherical particles of chitosan, oleic acid, and eugenol that are cross-linked to fibers. The nanoemulsion caused complete destruction of pathogens even for the most rigid biofilms formed by drug resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans on the surface of the coated fabric. The secondary coat with beeswax imparts super hydrophobicity and 20 wash cycle resistance and leads to enhanced barrier properties with superior particulate filtration, bacterial filtration, and viral penetration efficiency as compared to an N95 respirator. The coated fabric qualifies as per standard parameters like breathability, flammability, splash resistance, and filtration efficiency for submicrometer particles, bacteria, and viruses. The scaleup and bulk manufacturing of the coating technology on fabric masks complied with standards. The consumer feedback rated the coated mask with high scores in breathability and comfortability as compared to an N95. The strategy promises to provide a long-term sustainable model compared to single use masks and PPE that will remain a nondegradable burden on the ecosystem for years to come.

A novel face mask design with improved properties for COVID-19 prevention

Novel cloth face masks to mitigate the spread of COVID-19 have been developed and tested for particle (0.1 μm in size) filtration efficiency, bacterial filtration efficiency, breathability, leakage, heart rate, and blood oxygen level, and then compared with the available N95 masks and surgical masks. It was found that this novel mask had better filtration efficiency than that of surgical masks and was very close to that of N95 masks. The breathability was also improved and was in the range of the designated levels for barrier face coverings. The flow visualization technique was utilized to study the leakage of the mask and it was found to have significantly lower leakage as compared to surgical masks. Heart rate and blood oxygen level tests were performed by wearing the mask during 10-minute walking sessions and it was found that wearing the mask did not adversely affect heart rate or blood oxygen levels or add any other strain on the wearer. It is believed that this novel face mask would reduce the spread of COVID-19 as well as provide an environmentally and economically conscious alternative to the N95 respirators for the public. The mask developed in this study can be washed, reused, and therefore worn for longer periods of time.