Preparation and Characteristic of Antibacterial Facemasks with Chinese Herbal Microcapsules
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Aerosol and Air Quality Research, 17: 2119–2128, 2017
Copyright © Taiwan Association for Aerosol Research
ISSN: 1680-8584 print / 2071-1409 online
doi: 10.4209/aaqr.2017.06.0208
Preparation and Characteristic of Antibacterial Facemasks with Chinese Herbal
Microcapsules
Ya-Fen Wang1*, Fei Kang1, Sheng-Jie You1, Cheng-Hsien Tsai2, Geng-Le Lin1
1
Department of Environmental Engineering, Chung Yuan Christian University, Chungli 320, Taiwan
2
Department of Chemical and Materials Engineering, Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan
ABSTRACT
Along with the current increases in human activities, air pollution, especially that generated from bioaerosols, has begun
to receive more extensive attention. Among the bioaerosols, bacteria and fungi can result in organisms that are pathogenic
to animals and humans. Therefore, a biological protective respirator with an antibacterial function would be a significant
method by which to prevent epidemic spread of respiratory infectious diseases and protect human health. In this study, a
type of facemask with an antibacterial function was prepared. The structure of the respirator included a respirator body and
an inner filter layer that was assembled with herbal microcapsules. A kind of Chinese herb microcapsule developed
through a cross-linking reaction method was successfully prepared to serve as an important component of the respirator.
Scutellaria baicalensis (SB), a typical Chinese medicine, was employed to prepare the Chinese herb microcapsule. Three
kinds of filter cloth (cotton, polyester fiber, and non-woven fabric, respectively) were employed to assemble with Chinese
herb microcapsule. Meanwhile, the antibacterial performance and adhesion of the Chinese herb microcapsule for E. coli
and S. aureus were investigated. The measurement results revealed that (i) the antibacterial efficiency of the Chinese herb
microcapsule and the respirator filter was above approximately 99.999 and 96.000%, respectively; (ii) the adhesion of the
herb microcapsules was still excellent after the filter was washed 100 times; (iii) the as-prepared antibacterial filter
modified by an O2 plasma-surface (PSM-O2) treatment exhibited excellent antibacterial performance. Finally, a chamber
simulation utilizing an Anderson first order sampler was designed to simulate the effect of wearing the antibacterial filter
in a real environment. Overall, the respirator exhibited excellent biological protection properties compared with general
masks, which will satisfy a vast number of application prospects.
Keywords: Chinese herbal medicine; Microcapsules; Antibacterial efficiency; Mask; Respirator filter.
INTRODUCTION it is very necessary for people to wear a biological protective
respirator with an antibacterial function. A facemask, as a
Bioaerosols generated from airborne particles of biological kind of simple and convenient respirator, is widely used in
origin include fungi, bacteria, viruses, and fragments of daily life. It has been demonstrated that wearing facemasks
the foregoing or their metabolic products (e.g., endotoxins, for a long time can reduce the probability of infection from
mycotoxins) (Chow et al., 2015; Walser et al., 2015; Chen et influenza-like illnesses (MacIntyre et al., 2009; Natarajan et
al., 2016; Zhang et al., 2016; Lal et al., 2017). Environmental al., 2016; Lin et al., 2017). Especially, functional facemasks
health studies have indicated that constant exposure to are recommended for frontline healthcare workers to prevent
bioaerosols containing high concentrations of bacteria can splashes and sprays of blood, body fluids and the spread of
lead to respiratory diseases including allergies, infections, infection from the wearer (Siegel et al., 2007; Agarwal et
and other adverse health effect (Bünger et al., 2007; Lu et al., 2016). At present, polypropylene (PP) melt-blown
al., 2016; Mirhoseini et al., 2016). With the current increases nonwoven fabric has been extensively employed as a filter
in atmospheric pollution, human respiratory systems have for biological protective respirators because it resists
been suffering from more health risks both indoors and microparticles and pathogenic microorganisms based on
outdoors when exposed to biological aerosols. Therefore, physical effects. However, bacteria, viruses, and other
microorganisms remaining on filter materials can survive
and multiply under suitable conditions and result in secondary
infections in humans (Chow et al., 2005). Hence, a facemask
*
Corresponding author. filter with an antibacterial function is urgently needed (Lee
Tel./Fax: +886-32654912 et al., 2017; Rissler et al., 2017).
E-mail address: yfwang@cycu.edu.tw Traditional Chinese herbal medicines, having a long
2120 Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017 history of treating diseases, serve as an established segment MATERIALS AND METHODS of the public health system in China at present and have attracted much more concern in other parts of Asia (Chen Experimental Materials and Zhu, 2013). According to the third national survey on All chemicals used in our experiment were of analytical Chinese material resources, there are more than 12,000 grade and were used without further purification. The medicinal plants (Kong et al., 2004). Literally, traditional following materials were used: chitosan amine (ACROS, Chinese medicine utilizes multiple plant prescriptions made 99.9%), citric acid (99.5%), sodium alginate (SIGMA, 99%), from their extraction agents that have served the health calcium chloride (chemical projects, 99%), sodium chloride needs of the Chinese general public for over 5000 years (BIO BASIC INC., 99.5%), glutaraldehyde, acetic acid (99%, (Mahady et al., 2008). For example, Scutellariabaicalensis chemical projects), ethanol (95%, chemical projects), and (SB), a traditional Chinese medicine, comprises several methanol (99.9%, chemical projects). Scutellaria baicalensis biological activities including anti-oxidative, anti- (SB) was purchased from the Combined Chinese and inflammatory, antibacterial, and antiviral activities ((Duan et Western Medicines (No.397, jianxing road, North District, al., 2007). Compared to antibiotics, Chinese herbal medicine Taichung). A soybean protein decomposition comprising has mild pharmacology, a high degree of safety, curative dry plain agar and soybean protein in a state of medium effectiveness, is low cost, and is not compromised by dry decomposition were bought from Tryptic Soy Agar drug-resistant bacteria. Therefore, an increasing number of (TSA), Scharlau, Scharlab, S.L., Barcelona, Spain. Also, antibacterial respirators employing Chinese herbal medicine the fabric was purchased from the Ming-Yang Textile Co., has emerged (Chen and Zhu, 2013; Han et al., 2015; Mazzio Hong Kong. Escherichia coli (E. coli) and Staphylococcus et al., 2016). aureus (S. aureus) were purchased from the Institute of Microcapsule technology offers various significant Food Hygiene, Berlin. applications in many fields, including chemical science, bioscience, biotechnology, and drug delivery systems Preparation of Chinese Herbal Extraction (Singh et al., 2010). It is reported that microcapsules can Firstly, the extraction of the Chinese herbal medicine increase the adhesive strength with fiber and slow down used in this study was conducted via the Soxhlet extraction the process of drug release (De Geest et al., 2009; Hebeish method (Snyder et al., 1992). Secondly, the extraction was et al., 2011). Otherwise, Plasma-surface modification (PSM) centrifuged and filtered to remove any impurities. Thirdly, the is an effective and economical surface treatment technique pure extraction was concentrated by vacuum decompression for many materials and is of growing interest in the field of rotary concentrator (EYELA). The concentrated solution of biomedical engineering (Encinas et al., 2012). In particular, the Chinese medicine was frozen in a refrigerator at –20C plasma treatment can improve adhesion strength, surface, overnight. Then, the concentrated solution was freeze-dried and coating properties as well as mechanical- and bio- until no water remained. Finally, the powder samples were compatibility (Chu et al., 2002; Encinas et al., 2012; stored in a refrigerator at 4C for subsequent microcapsule Armağan et al., 2014). With respect to atmospheric plasma synthesis. on the poly (lactic acid) (PLA) surface, plasma treatment promotes an increase in the surface energy of 59% from Preparation of the Chinese Herbal Microcapsules values of around 37.10 mJ m–2 to values close to 58.92 mJ m–2. Preparation of Chinese Herb Microcapsule by Cross- This treatment of the PLA surface induces the appearance of Linking Reaction new activated species, such as carboxyl (ACOOH), carbonyl Chitosan was also employed as a cladding material (ACO), hydroxyl (AOH), peroxide (AROORA), and other (Kanmani et al., 2011). Gelatin was used as a substrate in functional groups, which change overtime to achieve a the formation of the microcapsules. The Chinese medicine stable state (Jordá-Vilaplana et al., 2016). extraction served as a core material. After treatment involving In this work, a novel kind of mask with an antibacterial concentrating and freeze-drying, the Chinese herbal function was prepared. We used the extraction of scutellaria microcapsules were synthesized. The detailed procedures baicalensis (SB) to synthesis the Chinese herb microcapsule. are appended as follows: (i) Chitosan was dissolved in an A novel Chinese herb microcapsule method was successfully acetic acid solution (denoted as solution A). Subsequently, prepared using a cross-linking reaction during the process gelatin powder and the Chinese herbal medicine powder of respirator fabrication. Three kinds of filter cloth (cotton, were dissolved in deionized water and stirred at 2500 rpm polyester fiber, and non-woven fabric, respectively) were (denoted as solution B). (ii) Solution B was transferred to a compared to assemble with Chinese herb microcapsule. water bath at 50°C and stirred at 400 rpm (denoted as solution Meanwhile, the antibacterial performance and adhesion of the C). (iii) Solutions A and C were then mixed, and the pH Chinese herb microcapsule for E. coli and S. aureus were value was adjusted to 5.3 with 10% NaOH accompanied investigated. Moreover, a chamber simulation utilizing an by stirring at 400 rpm for 30 min (denoted as solution D). Anderson first order sampler was designed to simulate the (iv) Solution D was cooled to 5–10°C. The cross-linking effect of wearing the antibacterial filter in a real environment. reaction was conducted for 30 min after adding 2 mL 25% Overall, the respirator exhibited excellent biological glutaraldehyde to the cooled solution (denoted as solution protection properties compared with general masks, which E) (Singh et al., 2010). (v) Finally, the Chinese herb indicates that it may be significant in the control of microcapsule suspension was obtained after solution E bioaerosol and bacterial infections. was stirred for 30 min in a 40°C water bath.
Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017 2121
For comparison, the Chinese herb microcapsule without oxygen flow were controlled at 20 sccm (standard cubic
the cross-linking reaction method was also prepared centimeter per minute). Thirdly, the tailored filter fabric
following the above procedure without process (iv). was treated with low-temperature plasma for 30 seconds to
modify the surface.
Assembly Filter with the Chinese Herb Microcapsule As a contrast, the filter containing the Chinese herbal
Pre-Processing with Filter Cloth microcapsule without plasma treatment was also prepared.
Three kinds of filter cloth (cotton, polyester fiber, and
non-woven fabric, respectively) were soaked in a 5% Antibacterial Performance Evaluation
detergent solution for 30 min and then ultrasonically Minimum Antibacterial Concentration Test
oscillated at 45°C for 1 h in order to eliminate the processing Due to the fact that E. coli and S. aureus are respectively
pulp material. Afterwards, the cotton fabric was washed representative of Gram-positive and Gram-negative bacteria
and rinsed with deionized water and then soaked in acetone (Fischer et al., 2015), a series of different concentrations
for 10 min to remove any remains on the fabric surface. It of an SB (from 0.0078125 to 2 g mL–1) extraction was
was then dried at 75°C in an oven. The treated fabric was respectively employed to inhibit the E. coli and S. aureus. In
tailored into an appropriate size and placed in an ultrasonic brief, the original bacterial solution (E. coli and S. aureus)
concussion machine for 10 min to get rid of the fabric was diluted to 2 105 CFU mL–1. Different concentrations
clippings. Finally, the obtained fabric was reserved as a of the Chinese herbal extraction were added into the above-
filler material after drying in an oven. mentioned solution. The culture medium TSA sterilized at
a high temperature was added and mixed uniformly. Then,
Preparation of the Filter with the Chinese Herbal the culture dish was cultivated in an incubator at 37°C for
Microcapsule 24 h. Finally, the number of colonies was calculated.
The treated fabric was weighed and the mass was recorded
as m1. Then, it was immediately soaked into a suspension Antibacterial Performance Test of Chinese Herb
containing the Chinese herb microcapsule for 5 min. and Microcapsules
then dried and solidified gradually on the soaked fabric. The culture medium TSB mixed with the E. coli or S.
Finally, the filter with Chinese herbal microcapsule was aureus colony, respectively, and cultivated at 37°C and 85
prepared successfully, and the filter mass was labeled m2. rpm for 24 h. Each of the two Chinese herbal microcapsule
Before testing the antibacterial efficiency of the suspensions was respectively added into the above diluted
microcapsules, the coating efficiency should verified as bacteria solution (2 105 CFU mL–1). The antibacterial
stable. The coating efficiency of the Chinese herb results of the Chinese herb microcapsules was measured
microcapsule was calculated by the following equation: after 0, 2 4, 6, 12, 24, 48, 72 hr, orderly). Namely, 1 mL of
the mixed solution was respectively taken and solidified.
m2 m1 The number of colonies was then counted. For comparison,
Coating efficiency (%) = 100% (1) the blank group (the same bacterial solution without the
m1
Chinese herbal extraction or microcapsules) was counted.
The antibacterial efficiency was then calculated using the
Plasma-Surface Modification (PSM) of the Fabric following equation:
The pre-processed fabric was treated using a low-
temperature plasma system. The schematic of the set-up
N0 N
system is shown as Fig. 1. Firstly, the sample table was Antibacterial efficiency (%) = 100% (2)
wiped with acetone after breaking the chamber vacuum. N0
The tailored filter material was then placed on it. Secondly,
residual gases and substances in the chamber were removed where N0 is the number of bacterial colonies for the blank
using a vacuum pump. The pressure was controlled at 600 experiment, and N is the number of bacterial colonies in
torr (1 torr = 133 Pa) with argon gas, and the argon and the presence of the Chinese herbal element.
Fig. 1. Schematic illustration of plasma set-up system for treating pre-processed fabric.
2122 Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017
Antibacterial Performance Test of the Filter with the
Chinese Herbal Microcapsule
The antibacterial test method for the filter containing the
Chinese herbal microcapsule followed AATCC-100 2004
(Gao and Cranston, 2008).The number of colonies was
counted and calculated to determine the antibacterial
efficiency.
Durability Test of Antibacterial Filter
The filter with the Chinese herbal microcapsule was
washed using a 5% detergent and was then vibrated
ultrasonically for 3 min and dried circularly 0, 10, 30, 50,
70, 90, and 100 times. The washed antibacterial fabric
filter at the different times was investigated with an
antibacterial test using the AATCC-100 2004 method.
Simulated Test Filter with the Chinese Herbal
Microcapsule
Chamber Simulation
For the purpose of testing the effect of wearing the
antibacterial filter, a chamber simulation was designed to
simulate the human lung (Fig. 2). In this study, an Anderson
first order sampler was used for sampling (Heinrich et al.,
2003; Lin et al., 2012). The chamber volume was 100 L,
and the height of the sampling port was set at 150 cm from
the ground. Before sampling, the pumping frequency was
adjusted to once every 3 seconds at a pumping volume of
500 mL.
Fig. 2. Schematic illustration of the sampling chamber.
Antibacterial Performance of Filter for Bioaerosol
Firstly, the antibacterial filter with the Chinese medicine
microcapsules was placed in the sampling port. A controlled microcapsules. A structural diagram of the antibacterial
pumping system was used to simulate breathing frequency, mask is shown as Fig. 3 (side view (A) and front view (B)).
which was maintained for 200 min. An Anderson first The three layers from inner to outer are medical cotton yarn,
order sampler was used for a 3-min sampling. The sample the antibacterial filter, and non-woven fabric, respectively.
was cultivated in a bacterial culture substrate at 37°C for
48 h. After cultivating at 25°C for 5 days, the number of RESULTS AND DISCUSSION
colonies was calculated. For comparison, the filter without
any process was also analyzed in the above experiment. Antibacterial Performance Evaluation
Minimum Antibacterial Concentration Test
Preparation of the Antibacterial Mask Before preparing the Chinese herb microcapsule, the
The structure of the respirator included a respirator body minimum antibacterial concentration of the Chinese herb
and an inner filter layer, which was assembled with herbal extraction was tested. Fig. 4(A) shows that SB exhibited
Fig. 3. Structure diagram of antibacterial facemask.Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017 2123
Fig. 4. The number of colonies (A) and antibacterial efficiency (B) for E. coli and S. aureus after treating bacterium
culture solution with different concentrations of SB (0.1, 0.05, 0.025, 0.0125, 0.00625, and 0.003125 g mL–1).
excellent antibacterial performance for both E. coli and for E. coli and S. aureus was still maintained at 99.999%
S.aureus after treating the bacterium culture solution with when the Chinese herbal microcapsules were diluted by
different concentrations of SB (0.1, 0.05, 0.025, 0.0125, 100 times. However, the antibacterial capacity started to
0.00625, and 0.003125 g mL–1). The results showed that decline sharply after being diluted more than 100 times,
the minimum antibacterial concentrations of SB for E. coli especially in the case of E. coli. Therefore, microcapsules
and S. aureus were 0.2 and 0.0125 g mL–1, respectively. diluted 100 times were employed to test bacterial growth
Fig. 4(B) illustrates that the inhibition effect of S. aureus for 48 h.
revealed a higher degree of selectivity as compared with E. Fig. 5(D) presents the bacterial multiplication for 48 h
coli. According to a previously reported work, we concluded in culture solution contained CHM2 (diluted 100 times). As
that Gram-negative bacteria (E. coli) has both a double- observed, the antibacterial results for S. aureus showed
layer membrane and a lipopolysaccharide layer. These escalating trend during the initial period. It was because that
layers act as a barrier to the entry and exit of other objects microcapsule was released slowly. Overall, the antibacterial
(Jiang and Zhang, 2016). Therefore, a higher concentration performance of CHM2 (diluted 100 times) for E. coli and S.
of SB is needed to achieve a better antibacterial effect. aureus was excellent until 24 h. While the antibacterial
capability started to decline down to 60 and 74% (for S.
Antibacterial Performance Test for the Chinese Herbal aureus and E. coli, respectively) at 36 h. It was speculated
Microcapsules that the amount of released Chinese medicines from the
To make better use of SB to inhibit the multiplication of microcapsules was not enough to inhibit multiplication of
bacteria, a novel Chinese herbal microcapsule developed bacteria. At 48 h, CHM2 almost showed no antibacterial
using the cross-linking reaction method was successfully performance.
prepared. For comparison, the Chinese herb microcapsule
without the cross-linking reaction method was prepared. It Characterization of the Filter Cloth with the Chinese
was only coated with the Chinese herbal medicine chitosan Herbal Microcapsule
(denoted as CHM1). With respect to the antibacterial Three kinds of readily available filter cloth (cotton,
efficiency of CHM1, the overall release rate of the polyester fiber, and non-woven fabric, respectively) were
microcapsules for S. aureus was superior to that of E. coli. employed to study the antibacterial performance and the
After 24 h, the antibacterial efficiency was still maintained adhesion of the herbal medicine after assembly with the
at more than 96%, as compared with E. coli (86.29%). Hence, Chinese herbal microcapsule.
CHM1 exhibited relatively poor antibacterial performance for Fig. 6 shows the morphology and size of the as-prepared
S. aureus, as shown in Fig. 5(A). filter cloth as characterized by SEM. The results reveal
In the case of the Chinese herbal microcapsule developed that the Chinese herbal microcapsules (marked in the
using the cross-linking reaction method (denoted as yellow circle) were successfully assembled with the cotton
CHM2), Fig. 5(B) shows excellent antibacterial efficiencies (Fig. 6(A)), polyester fiber (Fig. 6(C)), and nonwoven fabric
for both of E. coli and S. aureus after 24 h of as much as (Fig. 6(E)), and these microcapsules aggregated excessively.
99.999%. We can therefore conclude that the antibacterial Also, it can be observed that the structure of the nonwoven
performance of the CHM2 microcapsule was superior to fabric was different from that of the other fabrics. The
that of CHM1. In order to reduce the cost, different dilution nonwoven fabric presented disordered, unsystematic features.
concentrations (10, 100, 1000 and 10000 times) of CHM2 From their corresponding high-magnification images
were tested. As shown in Fig. 5(C), the antibacterial ability (Figs. 6(B), 6(D) and 6(F)), it can be observed that the2124 Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017
Fig. 5. Antibacterial efficiency of Chinese herb microcapsule without cross-linking reaction method (A) and by cross-
linking reaction method (B) for 24 h; (C)Antibacterial efficiency of Chinese herb microcapsule by cross-linking reaction
method after diluted by different times (10, 100, 1000 and 10000 times). (D) Antibacterial performance evaluation of
Chinese herb microcapsule by cross-linking reaction method (after diluted 100 times) for 48 h.
pattern of the nonwoven fabric was much more loosened plasma-surface (PSM-O2) treatment exhibited a much
and rough than its counterparts. higher microcapsule residual rate after 100 washings, as
calculated using the following equation:
Antibacterial Performance Test of the Filter Cloth with
the Chinese Herbal Microcapsule m2 m0
As shown in Fig. 7, the antibacterial efficiency and Residual rate (%) = 100% . (3)
adhesion of the herbal medicine for the different types of m1 m0
filter cloth with CHM2 were measured after they were washed
100 times. The results showed that the antibacterial where m0 is the initial weight of filter cloth; m1 is the weight
efficiency of the filter cloth with CHM2 (assembled with of filter cloth after coating with antibacterial microcapsules,
cotton, polyester fiber, and non-woven fabric, respectively) and m2 is the weight of the above-mentioned filter after
for E. coli and S. aureus still remained above 96% (96.94, 100 washings.
96.69, 96.99%) and above 95% (95.65, 96.33 and 96.67%), We speculated the reason this outcome was that
respectively, although there was a slight downward trend modification by PSM-O2 not only improves the physical
after 100 washings. Further, it was proved that all types of properties of the surface, but also increases the oxygen
filter cloth assembled with CHM2 can maintain stable functional groups and hydrophilic performance (Jordá-
adhesion and can be re-used many times. Vilaplana et al., 2016). It has been reported that the
In order to strengthen overall capacity, the above hydrophilicity of a biomaterial is related to the adhesion of
referenced as-prepared filter cloth with CHM2 was treated microbial proteins, which provide an additional hydration
with plasma-surface modification (PSM). Compared with layer that prevents protein adhesion (Wei et al., 2014).
PSM-Ar, the filter cloth with CHM2 modified by the O2 This would suppress the breeding of microorganisms onWang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017 2125
Fig. 6.SEM images of the filter cloth with Chinese herb microcapsule by cross-linking reaction method: cotton (A, B),
polyester fiber (C, D) and non-woven fabric (E, F). B, D and F are the high-magnification SEM images for A, C and E,
respectively.
the surface of such biomaterials. After being treated with effect of wearing the antibacterial filter in a real environment,
PSM-O2, the antibacterial efficiency and adhesion of the a chamber simulation was designed to simulate the human
herbal medicine for the different types of filter cloth with lung (Fig. 2). In this study, an Anderson first order sampler
CHM2 were measured after washing 100 times. As shown was used for sampling. We recorded the number of bacterial
in Figs. 8(A) and 8(B), the results show that the antibacterial colonies for the three types of filter cloth with CHM2 for
efficiency of the non-woven fabric with CHM2 for E. coli 24 h. For comparison purposes, a blank sample was also
and S. aureus could be maintained above 99% and 96%, employed to calculate the multiplication of bacterial colonies.
respectively, after 100 washings. In the case of the cotton The three sampling results indicate that the number of
fabric, the increase in antibacterial efficiency was not bacterial colonies in the cotton coated with the Chinese herbal
remarkable (97 and 95%) while the antibacterial efficiency microcapsules was 17, 20 and 19 CFU m–3, respectively.
of the polyester fiber fabric with CHM2 for E. coli and S. For the polyester fiber, the number of bacterial colonies
aureus declined sharply (78.6 and 73.4%). This is because was 33, 35 and 30 CFU m–3. For the nonwoven fiber, the
the fabric fibers were so close together that there were not number of bacterial colonies was 10, 11 and 12 CFU m–3.
enough holes for microcapsule preservation. Therefore, the However, the number of bacterial colonies was 408, 417
microcapsules fell off the surface of the fabric when it was and 405 CFU m–3 in the blank group. Fig. 9(A) shows the
treated with PSM-O2. antibacterial performance results. As can be seen from the
bar chart, the nonwoven fiber with the Chinese herbal
Simulation Test of the Filter with the Chinese Herbal microcapsules exhibited the best inhibition of multiplication
Microcapsule of bacterial colonies. The average value of the antibacterial
Both indoors and outdoors, bacteria and fungi always efficiency for the nonwoven fiber (97.31%) was higher
give rise to bioaerosols, which influences air quality and in than that of both the cotton (95.44%) and polyester fibers
turn the human respiratory system. In order to test the (91.7%).2126 Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017 Fig. 7. Antibacterial performance of three kinds of filter cloth (cotton, polyester fiber and non-woven fabric, respectively) coated with Chinese herb microcapsule after washed by 100 times. The top of the graph is antibacterial efficiency for E.coli, and the bottom for S. aureus. Fig. 8. Antibacterial efficiency of different kinds of filter cloth with CHM2 treated with PSM-O2 after washed by 100 times. The left (A) antibacterial efficiency for E.coli, and the right (B) for S. aureus. At the same time, we also recorded the number of fungi. stability. The three sampling results show that the number of fungi in the cotton coated with the Chinese herbal microcapsules CONCLUSION was 62, 60, and 62 CFU m–3, respectively. For the polyester fiber, it was 62, 60 and 61 CFU m–3. For the nonwoven fiber, In summary, a novel type of mask with an antibacterial it was 51, 50 and 55 CFU m–3. For the blank fiber, it was function was prepared. We used an extractant of scutellaria 716, 724 and 715 CFU m–3. Fig. 9(B) shows the antibacterial baicalensis (SB) to synthesize the Chinese herbal performance results. As was previously observed, all of the microcapsule. A novel Chinese herbal microcapsule filters with the Chinese herbal microcapsules exhibited the developed using a cross-linking reaction method was same performance related to inhibiting the multiplication of successfully prepared during the process of respirator fungi. The average antibacterial efficiency for the nonwoven fabrication. Three types of filter cloth (cotton, polyester fiber (92.66%) was slightly higher than that for the cotton fiber, and non-woven fabric, respectively) were compared (91.45%) and polyester fibers (91.04%). Overall, these three when assembles with the Chinese herbal microcapsule. types of filters exhibited excellent antibacterial capability and Meanwhile, the antibacterial performance and adhesion of
Wang et al., Aerosol and Air Quality Research, 17: 2119–2128, 2017 2127
Fig. 9. Antibacterial capability of three kinds of filter cloth with CHM2 in the real environment for bacteria (A) and fungi
(B) to simulate the effect of wearing the antibacterial filter.
the Chinese herbal microcapsule for E. coli and S. aureus (2016). Control of bioaerosols in indoor environment by
was investigated. The experimental results are summarized filter coated with nanosilicate platelet supported silver
as follows: (a) the antibacterial efficiency of Chinese herb nanohybrid (AgNPs/NSP). Aerosol Air Qual. Res. 16:
microcapsule and the respirator filter was as high as 2198–2207.
approximately 99.999 and 96.00%, respectively; (b) the Chen, Y. and Zhu, J. (2013). Anti-HBV effect of individual
adhesive strength of the herbal microcapsules maintained traditional Chinese herbal medicine in vitro and in vivo:
excellent performance after the filter was washed 100 times; An analytic review. J. Viral Hepat. 20: 445–452.
(c) the as-prepared antibacterial filter modified using an O2 Chow, J.C., Yang, X., Wang, X., Kohl, S.D., Hurbain, P.R.,
plasma-surface (PSM-O2) treatment exhibited much higher Chen, L.W.A. and Watson, J.G. (2015). Characterization
antibacterial performance. A chamber simulation utilizing of ambient PM10 bioaerosols in a california agricultural
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excellent antibacterial capability and stability, and are the MVAC system in an office premise. Proceedings of
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and Climate – Indoor Air 2005, Sep 4–9, 2005, Beijing,
ACKNOWLEDGEMENTS China, pp. 1096–100.
Chu, P.K., Chen, J.Y., Wang, L.P. and Huang, N. (2002).
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of Science and Technology, Taiwan (Project No: MOST- Eng., R 36: 143–206.
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