Various performance testing methods exist for antimicrobial finishes as protective functional textiles. Various qualitative and quantitative testing methods for antimicrobial performance of textiles are described in detail; the key factors affecting the effectiveness of antimicrobial performance testing of textiles are also discussed.
1. Selection of test strains
The test strains include bacteria and fungi. Among bacteria, Gram-positive and Gram-negative bacteria are mainly used, and among fungi, molds and fungi are mainly used.
In the evaluation of antimicrobial performance of textile antimicrobial fabrics, the selection of strains must be scientific and representative. The strains listed in Table 1 are widely distributed in nature (including human skin and mucous membrane).
Staphylococcus aureus is a pathogenic bacterium with strong resistance among non-budding bacteria, and can be used as a representative of Gram-positive bacteria. Bacillus megaterium is a common pathogenic bacterium in the bacillus category; Bacillus subtilis is easy to form bacilli and has a strong resistance, and can be used as a representative of bacillus. E. coli is quite widely distributed, has been used as a representative of the usual Gram-negative bacteria for various tests. Aspergillus flavus, the ball of Trichoderma spp. as the specified mold test with strains, has been included in our national standards (GB2423.16-81), some other selected mold, is the erosion of textiles or polymer materials common mold. Candida albicans is a common condition pathogenic fungus of human skin mucous membrane, sensitive to drugs, with the characteristics of fungi, colonies similar to bacteria and not bacteria and different from mold, because of the cool bacteria colonies, easy to count and observe, often as a representative of the fungus.
Therefore, in order to assess whether the textile antibacterial fabric has a broad-spectrum antibacterial effect, a more reasonable choice is to a certain proportion of representative strains of bacteria into a mixture of strains for testing. At present, most of the antibacterial performance of antibacterial products, often only choose Staphylococcus aureus, Escherichia coli and Candida albicans as Gram-positive bacteria, Gram-negative bacteria and fungi, respectively. But in fact, it is far from enough to use only these three bacteria to represent the antibacterial performance of fabrics .
In addition, because most of the fungi can not count the number of colonies, therefore, the evaluation of textile anti-fungal performance is mainly through the observation of the specimen after contact with fungi, in a certain temperature and humidity conditions, after a certain period of time, the growth of fungi on the specimen to assess, and the assessment of the degree of fungal growth, the British Standard BS6085-81 to grade.
2. Textile antibacterial performance test methods
Textile antibacterial fabric performance test methods mainly include qualitative test methods, semi-quantitative test methods and quantitative test methods.
2.1 Qualitative test methods
Qualitative test methods are mainly the United States AATCC Test Method90 (Halo Test, halo method, also known as agar dish method), JISZ2911-1981 (anti-microbial test method), AATCC-30 (textile materials anti-mold and anti-decay performance assessment) and GB/T 20944.1-2007 (textile antibacterial performance evaluation part 1: agar dish diffusion method) and so on. The qualitative test method consists of inoculating test bacteria on the fabric and observing microbial growth on the fabric with the naked eye. It is based on the activity of antimicrobial agent leaving the fiber into the petri dish, and is generally suitable for lysing antimicrobial finishing, but not for washing-resistant antimicrobial finishing. The advantage is low cost, fast, the disadvantage is not quantitative determination of antibacterial activity, the results are not accurate.
2.1.1AATCC-90 test method
It is a rapid qualitative method for antimicrobial agent screening. The principle is: inoculate the test bacteria on the agar medium, and then adhere to the sample. After 24 hours of incubation at 37℃, the bacterial multiplication and the size of the halo in the sterile area around the sample are observed with a magnifying glass and compared with the test condition of the control sample. This method can handle a large number of samples at one time, the operation is simpler, and the time is short. However, there are some problems, such as although the provisions of a certain period of time to cultivate the test solution, but the bacterial concentration is not clearly defined. In addition, the width of the blocking band represents the diffusivity and antimicrobial efficacy, which is meaningful for comparison with standard fabrics, but cannot be used as a quantitative assessment of antimicrobial activity .
2.1.2AATCC-90 spray method
The AATCC-90 spray method is a modification of the AATCC-90 test method, in which a certain amount of TNT reagent is sprayed on the cultured specimen and the growth of bacteria on the specimen is observed visually. The coloring principle is that the TNT reagent is reduced by the action of succinate dehydrogenase of the test bacteria to produce insoluble red pigment, so as to achieve the purpose of determining the antibacterial properties. The advantage of this method is that regardless of whether the sample has the formation of the inhibition circle, as long as there is bacterial growth on the plate, it will show the red color.
2.1.3AATCC-90 colorimetric method
AATCC-90 colorimetric method is also an improvement of the AATCC-90 test method, is to add a certain amount of TNT reagent in the culture sample of bacteria washout to make the color, 15 min after the spectrophotometer to determine the absorbance at 525 nm, to find the number of live bacteria. However, the above two methods are not applicable to the test bacteria without succinate dehydrogenase.
2.1.4 J ISZ2911 anti-mold test method
The method is the early results of the research ideas in the mold detection, the basic principle is: in the sample and the medium evenly sprayed with a certain amount of mixed spore suspension, culture for a certain period of time, regular observation of the sample mold growth, according to the growth of mold in the grade evaluation of the sample's anti-mold performance.
2.1.5AATCC 30 test method
AATCC-30 is the assessment of the performance of textile materials against mold and decay. Determined the performance of textile materials to resist mold and rot resistance to assess the effectiveness of fungicides on the antibacterial properties of textile materials. Divided into several methods such as soil burial method, agar plate method and humidity bottle method. Soil burial method refers to the sample (with a certain size) buried in the mud for a certain period of time, to determine the fracture strength of the sample. This method is used to characterize the fracture strength of the sample by the loss of soil buried after treatment of mold resistance. Agar plate method is used to assess the ability of fabrics to resist this type of bacteria. The method is a certain amount of agar plate containing medium evenly dripped with dispersed Aspergillus spores of aqueous solution, and then the non-ionic wetting agent treatment of the sample disc placed on it, and a certain amount of the above aqueous solution evenly dripped on the sample disc, placed at a certain temperature for a period of time, after observing the growth of mold on the sample. It is used to characterize the area of the mold on the sample disc. Humidity bottle method is a pretreatment of the sample strip hanging in a certain amount of ventilation, containing a certain amount, dispersed with a certain number of bacterial spores in a wide mouth bottle, placed at a certain temperature for a period of time. This method is also characterized by the area of mold on the sample strip .
2.1.6 GB/T 20944.1-2007 Evaluation of antibacterial properties of textiles Part 1: agar flat dish diffusion method
This standard is a new domestic qualitative test method for textile antibacterial properties, the flat dish is injected with two layers of agar medium, the lower layer is sterile medium, the upper layer is inoculated medium, the specimen is placed on the two layers of medium, and after a certain period of incubation, the antibacterial properties of the specimen are evaluated qualitatively according to the degree of bacterial multiplication at the contact between the medium and the specimen .
2.2 Semi-quantitative test method
The semi-quantitative test method for textile antimicrobial properties is the parallel scribing method.
Parallel scribing method is a semi-quantitative test method for antimicrobial efficacy of textiles, which can be used to qualitatively test the antimicrobial performance of textile materials with antimicrobial finishing relatively quickly and easily, and can be used to determine the antimicrobial ability of textiles with diffusible antimicrobial agents. It replaces the cumbersome A A T C C-1 00.
The AATCC-147 method is a semi-quantitative analysis of the antimicrobial performance of textile materials by adding a certain amount of culture solution (containing a certain number of spores of bacteria such as Staphylococcus aureus) dropwise to a Petri dish containing nutrient agar plates, forming five parallel stripes on the surface of the agar, and then placing the sample vertically on these Then the sample was placed vertically on these culture stripes and gently squeezed to make close contact with the agar surface and left at a certain temperature for a certain time. This method is used to characterize the antibacterial ability of the fabric by the width of the inhibition zone around the stripes in contact with the sample.
2.3 Quantitative test method
At present, the textile antibacterial performance quantitative test method is the main flask oscillation method and absorption method. Flask oscillation method is through the oscillation of textiles in the bacterial solution, so that bacteria and textiles containing antibacterial agent contact, according to the change in the number of live bacteria in the bacterial solution before and after the oscillation, as the main index of antibacterial performance. The absorption method is to add the specified concentration of bacterial solution drop by drop on the textile antibacterial fabric sample and the control sample without antimicrobial agent, incubate for a certain period of time under the specified conditions, wash the sample and the control sample with the specified eluent before and after incubation, and then count the live bacteria in the eluent. The antibacterial performance was evaluated by comparing the change in the number of viable bacteria before and after incubation.
The operation of the vibration method is relatively complex, and the application of the general standard is limited to non-soluble textile antibacterial fabrics; while the operation of the absorption method is more complex and time-consuming, but because it is a quantitative method, it is more applicable to soluble and non-soluble textile antibacterial fabrics, and the test conditions are closer to the actual human wear, so it is the current test results for the accurate method. From the scientific and practical point of view, this method should be the main development direction of future textile antibacterial performance testing.
Quantitative test standards include the following, the United States AATCCTest Method 100 (bacterium number determination method), J ISL1902-8 (1998) quantitative test method, FZ/T02021-92, modified Quinn (Quinn) experimental method, ASTM E 2149-2001 (fixation antimicrobial agent antibacterial dynamic test method ), GB/T20944.2-2007 (Evaluation of antimicrobial properties of textiles Part 2: Absorption method), etc. The advantages of quantitative testing methods are quantitative, accurate and objective, and the disadvantages are long time and high cost. The following is an introduction to the commonly used quantitative testing methods for textiles.
2.3.1AATCC Test Method 100 test method
This method was proposed in 1961 by the American Textile and Dyeing Association Standards Committee, and was basically finalized after revision in 1965 and 1981. The method proposed earlier, the impact of the larger, to quantitatively detect the bactericidal ability of the sample and the ability to inhibit bacteria. The principle is: in the test sample and control sample inoculated with test bacteria, after a certain period of exposure to add a certain amount of neutralization solution, strong shaking will be washed out of the sample residual live bacteria, to dilute the plate method to determine the concentration of eluate bacteria, compared with the control sample, calculate the percentage reduction of bacteria on antibacterial fabrics .
The disadvantages of this method is that a test of the body can not be too much, and take a long time; for non-leaching type specimens, can not be antibacterial performance evaluation; no details of the composition of the neutralization solution; and the bacteria solution is too rich in nutrients, and the actual wearing conditions are too large; the container is too large, not easy to operate.
On the basis of absorbing domestic and foreign experience, after a lot of experiments, it was improved to form a systematic quantitative test method system, which can meet the needs of antibacterial performance testing of different textile antibacterial fabrics, namely modified AATCC-100, the main points are as follows: change the specimen of AATCC-l00 method from a circle of 4.8 cm in diameter to a square of about 1.8 cm in side length, put it Put it into a 30 mL or 50 mL conical flask with cap. The inoculum was diluted with 0.85% ice-cold saline (0~4°C) instead of AATCC broth. Dilute the strain from approximately 108~109 cfu/mL to 1×105~2×105 cfu/mL to make the inoculum. The specimens were washed with 20 mL of 0.85% ice-cold saline instead of neutralizer.
The following formula was used to calculate the inhibition and bactericidal activity of the samples: Inhibition rate = number of viable bacteria of the blank control sample after 18 h - number of viable bacteria of the sample after 18 h / number of viable bacteria of the blank control sample after 18 h × 100% Bactericidal rate = number of viable bacteria of the blank control sample at "0" - number of viable bacteria of the sample after 18 h / "0 "The method can be used for antimicrobial test no matter for lysing type specimen or non-lysing type specimen, and the nutrients of the medium are suitable for the use conditions of the fabric.
2.3.2 J ISL1902-8 (1998) quantitative test method
Japanese scholars proposed improved methods to the American AATCC100 method, such as bacterial count determination method, bacterial proliferation inhibition test method, agar plate method, improved bacterial proliferation inhibition test method, improved AATCC100 test method, etc. Accordingly, the Japanese Industrial Standards Committee revised the JISL1902-1990 standard and developed the JISL1902-1998 standard .
2.3.3 FZ/T02021-92 test method
FZT01021-92 People's Republic of China textile industry standard, fabric anti-disturbance bacteria performance test method (hereinafter referred to as FZ/T method); test sample and control sample were placed in triangular bottles (test sample 2 bottles, control sample 1 bottle), after adding the indicator bacteria solution will control sample and zero time test sample on the bacteria immediately washed with buffer and determine the amount of bacteria, 20 h test sample After incubation at the appropriate temperature, the sample was also washed with buffer and measured the amount of bacteria, and then calculated the percentage of bacterial reduction of the sample.
2.3.4 Modified Quinn's test method
Experimental principle: The experimental bacterial solution is directly dropped on the fabric to be examined, so that the bacteria are fully exposed to the fabric for a certain period of time, and then covered with culture medium, so that the remaining bacteria grow. Compare the antibacterial sample bacteria amount decrease percentage, make a judgment on its antibacterial ability. Colony forming units were counted using a magnifying glass .
2.3.5 ASTM E 2149-2001 test method
ASTME 2149-2001 is an oscillatory test method, and the test operation is simpler than the absorption method, which is a more desirable test method at present. Oscillation method is inoculated with bacteria in a certain liquid, for the specimen of water absorption requirements are not high, for the fiber, whether it is powder or down feathers, or uneven fabric, any shape of the specimen can be applied, and the test of non-soluble and soluble antibacterial fabrics are very suitable. The test method can not only test fabrics, but also powder and granular materials, as well as other surface treatment solid materials .
2.3.6 GB/T 20944.2-2007 Evaluation of antibacterial properties of textiles Part 2: Absorption method
This standard is a new domestic quantitative test method for textile antimicrobial properties. The test principle is to inoculate the specimen and the control sample with the test bacterial solution respectively. Elution immediately and after incubation, respectively, the number of bacteria in the eluate is measured and the inhibition value or inhibition rate is calculated to evaluate the antibacterial effect of the specimen .
3.Key factors affecting the antimicrobial test method for textiles In this paper, we focus on the flask oscillation method and the absorption method in the quantitative test method.
3.1 Key factors affecting the effect of flask oscillation test Key factors affecting the test results of flask oscillation method include test bacteria
3.1.1 Test strain
Even if the same strain of microorganisms is used, but if the source is different, the sensitivity to antimicrobial finishing samples will be different, and the measured antimicrobial value will be different. Therefore, when measuring, try to
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