ISO 27447:2019
(Main)Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for antibacterial activity of semiconducting photocatalytic materials
Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for antibacterial activity of semiconducting photocatalytic materials
This document specifies a test method for the determination of the antibacterial activity of materials that contain a photocatalyst or have photocatalytic films on the surface, by measuring the enumeration of bacteria under irradiation of ultraviolet light. This document is intended for use with different kinds of semiconducting photocatalytic materials used in construction materials in flat sheet, board, plate shape or textiles that are the basic forms of materials for various applications. It does not include powder, granular or porous photocatalytic materials. This test method is usually applicable to photocatalytic materials produced for antibacterial effect. Other types of performance of photocatalytic materials, i.e. antifungal activity, antiviral activity, decomposition of water contaminants, self-cleaning, antifogging and air purification, are not determined by this method. The values expressed in this document are in accordance with the International System of Units (SI).
Céramiques techniques — Méthode d'essai de l'activité antibactérienne des matériaux photocatalytiques semiconducteurs
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 27447
Second edition
2019-07
Fine ceramics (advanced ceramics,
advanced technical ceramics) — Test
method for antibacterial activity
of semiconducting photocatalytic
materials
Céramiques techniques — Méthode d'essai de l'activité
antibactérienne des matériaux photocatalytiques semiconducteurs
Reference number
ISO 27447:2019(E)
©
ISO 2019
---------------------- Page: 1 ----------------------
ISO 27447:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 27447:2019(E)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Principle . 3
6 Materials . 4
6.1 Bacteria used and preparation for tests . 4
6.1.1 Film cover method. 4
6.1.2 Glass cover method . 4
6.1.3 Bacteria preparation. 4
6.2 Chemicals and implements . 5
6.2.1 General. 5
6.2.2 1/500 nutrient broth . 5
6.2.3 Nutrient broth . 5
6.2.4 Nutrient agar . 5
6.2.5 Soybean-casein digest broth with lecithin and polysorbate 80 (SCDLP). 5
6.2.6 Physiological saline solution . 5
6.2.7 Physiological saline solution for washout . 5
6.2.8 Non-ionic surfactant . 6
7 Apparatus . 6
7.1 Test equipment . 6
7.2 Cover film . 6
7.3 Cover glass . 6
7.4 Moisture preservation glass . 7
7.5 Glass tube or glass rod . 7
7.6 Paper filter . 7
7.7 Light source . 7
7.8 UV radiometer . 7
7.9 Punched metal sheet . 7
8 Test piece . 9
8.1 Film cover method . 9
8.2 Glass cover method . 9
9 Procedure. 9
9.1 General . 9
9.2 Film cover method .11
9.3 Glass cover method .11
9.4 UV irradiation condition .12
9.5 Measurement of the number of living bacteria .13
10 Calculation .14
10.1 General .14
10.2 Film cover method .14
10.3 Glass cover method .15
11 Test report .16
Annex A (informative) Examples of test results .18
Annex B (informative) Reference data of cover films and cover glasses .20
Annex C (informative) Reference data of damage caused by ultraviolet to bacteria .22
© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 27447:2019(E)
Bibliography .24
iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 27447:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 206, Fine ceramics. This second edition
cancels and replaces the first edition (ISO 27447:2009), which has been technically revised. The main
changes to the previous edition are as follows:
— updating of reference document and cross-references;
— replacement of “adhesive” with “cover” throughout;
— clarification of definition of “photocatalyst antibacterial activity value” (3.4, 3.5, 3.6, 3.7) in Clause 3;
— deletion of a definition of “fluorescent UV lamp” in Clause 3 due to updating of the reference document
ISO 10677;
— inclusion of a statement in Clause 5 regarding treatment of results measured by the viable bacterial
count method;
— NOTE 1 changed to body text in 6.1.3;
— revision of “storage period of 1/500 nutrient broth” from 1 month ago to 1 week ago in 6.2.2
(formerly 6.2.1);
— addition of a new subclause, 6.2.1, renumbering of subsequent subclauses and updating of cross-
references in Clause 6;
— addition of a new subclause, 7.1, and renumbering of subsequent subclauses in Clause 7;
— revision of Figure 1, Figure 4 and Figure 5;
— addition of “paper filter” apparatus in 7.6;
— replacement of “black light fluorescent lamp” with “light source” in 7.7 (formerly 7.5) and revision of
a statement in 7.7 that the light source shall be 351BLB or 351BL as specified in ISO 10677;
© ISO 2019 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 27447:2019(E)
— replacement of “ultraviolet light radiation mater” with “UV radiometer” in 7.8 (formerly 7.6) and
inclusion of a statement in 7.8 that the UV radiometer shall be used as specified in ISO 10677;
— NOTE changed to body text in 8.1;
— addition of a new subclause, 9.1, and renumbering of subsequent subclauses in Clause 9;
— revision of storage time of “the bacteria suspension in case of not using immediately” from 4 h to 2 h
in 9.2.1(formerly 9.1.1);
— NOTE 2 changed to body text in 9.2.2 (formerly 9.1.2);
— NOTE 2 and NOTE 3 changed to body text in 9.3.2 (formerly 9.2.2);
— addition of the test environment temperature (25 °C ± 3 °C) in 9.4.1;
— addition of a new subclause, 10.1, and renumbering of subsequent subclauses in Clause 10.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
vi © ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 27447:2019(E)
Introduction
This document was developed for antibacterial activity as a result of continuing efforts to provide
test methods for photocatalytic materials. However, antibacterial activity cannot be measured for test
pieces with permeable or rough surfaces, so other test methods are required.
Under the irradiation of photons, photocatalysts show diverse functions, such as the decomposition
of air and water contaminants, as well as deodorization, self-cleaning, antifogging and antibacterial
actions. These functions of photocatalysts are generally based on the action of active oxygen species
such as hydroxyl (OH) radicals formed on the surface of a photocatalyst (References [14] and [15]). The
energy- and labour-saving nature of photocatalysis has attracted keen interest when the photocatalyst
is activated by sunlight (or artificial lighting).
Practical applications of photocatalysts for both indoor and outdoor use have rapidly expanded in recent
years. Many kinds of photocatalytic materials have been proposed or are already commercialized,
based on ceramics, glass, concrete, plastics or paper. Such materials are produced by either the coating
or mixing of a photocatalyst; in most cases, titanium dioxide (TiO ).
2
However, the effect of photocatalysis is not easily inspected visually, and no appropriate or official
evaluation methods have been available to date. Some confusion has thus arisen as photocatalytic
materials have been introduced. Furthermore, the above-mentioned diverse functions of photocatalysts
cannot be evaluated with a single method; thus, it is necessary to provide different evaluation methods
for air purification, water decontamination and self-cleaning.
This document applies to the testing of the antibacterial activity of photocatalytic ceramics and other
materials produced by either the coating or the mixing of a photocatalyst. Standards for testing the
antifungal activity that use photocatalytic materials will be developed separately.
© ISO 2019 – All rights reserved vii
---------------------- Page: 7 ----------------------
INTERNATIONAL STANDARD ISO 27447:2019(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for antibacterial activity of
semiconducting photocatalytic materials
WARNING — Handling and manipulation of microorganisms that are potentially hazardous
requires a high degree of technical competence. Only personnel trained in microbiological
techniques should carry out tests.
1 Scope
This document specifies a test method for the determination of the antibacterial activity of materials
that contain a photocatalyst or have photocatalytic films on the surface, by measuring the enumeration
of bacteria under irradiation of ultraviolet light.
This document is intended for use with different kinds of semiconducting photocatalytic materials used
in construction materials in flat sheet, board, plate shape or textiles that are the basic forms of materials
for various applications. It does not include powder, granular or porous photocatalytic materials.
This test method is usually applicable to photocatalytic materials produced for antibacterial effect.
Other types of performance of photocatalytic materials, i.e. antifungal activity, antiviral activity,
decomposition of water contaminants, self-cleaning, antifogging and air purification, are not
determined by this method.
The values expressed in this document are in accordance with the International System of Units (SI).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 10677, Fine ceramics (advanced ceramics, advanced technical ceramics) — Ultraviolet light source for
testing semiconducting photocatalytic materials
ISO 80000-1, Quantities and units — Part 1: General
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
photocatalyst
substance that carries out many functions based on oxidization and reduction reactions under
ultraviolet (UV) irradiation, including decomposition and removal of air and water contaminants,
deodorization, and antibacterial, antifungal, antiviral, self-cleaning and antifogging actions
© ISO 2019 – All rights reserved 1
---------------------- Page: 8 ----------------------
ISO 27447:2019(E)
3.2
photocatalytic material
material in which or on which the photocatalyst is added by coating, impregnation or mixing
Note 1 to entry: Photocatalytic materials are to be used for building and road construction materials to obtain
the functions mentioned in 3.1.
3.3
antibacterial
condition inhibiting the growth of bacteria on the surface of flat surface materials or cloths
3.4
photocatalyst antibacterial activity value for film cover method
difference between the logarithms of the total number of viable bacteria on photocatalytic treated
materials after UV irradiation and on non-treated materials after UV irradiation
Note 1 to entry: This value includes the decrease in the number of bacteria without UV irradiation.
3.5
photocatalyst antibacterial activity value for glass cover method
difference between the logarithms of the total number of viable bacteria on photocatalytic treated
cloths after UV irradiation and on standard cloths after UV irradiation
Note 1 to entry: This value includes the decrease in the number of bacteria without UV irradiation.
3.6
photocatalyst antibacterial activity value with UV irradiation for film cover method
difference between the logarithms of the total number of viable bacteria on photocatalytic treated
materials after UV irradiation and on photocatalytic treated materials kept in a dark place
3.7
photocatalyst antibacterial activity value with UV irradiation for glass cover method
difference between the logarithms of the total number of viable bacteria on photocatalytic treated
cloths after UV irradiation and on photocatalytic treated cloths kept in a dark place
3.8
film cover method
test method to evaluate the antibacterial performance of photocatalytic flat surface materials
3.9
glass cover method
test method to evaluate antibacterial performance of photocatalytic cloths
4 Symbols
A average number of viable bacteria on non-treated specimens, just after inoculation
B average number of viable bacteria on non-treated specimens,
D
after being kept in a dark place
B average number of viable bacteria on non-treated specimens,
L
after UV irradiation of intensity L
C average number of viable bacteria on photocatalytic treated specimens,
D
after being kept in a dark place
C average number of viable bacteria on photocatalytic treated specimens,
L
after UV irradiation of intensity L
F growth value, after being kept in a dark place
BD
2 © ISO 2019 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 27447:2019(E)
F growth value, after UV irradiation of intensity L
BL
L UV irradiation intensity
L maximum logarithmic value of viable bacteria
max
L average logarithmic value of viable bacteria for three specimens
mean
L minimum logarithmic value of viable bacteria
min
M number of viable bacteria with glass cover method
M average logarithmic value of the number of viable bacteria for three non-treated specimens,
BA
just after inoculation
M average logarithmic value of the number of viable bacteria for three non-treated specimens,
BD
after being kept in a dark place
M average logarithmic value of the number of viable bacteria for three non-treated specimens,
BL
after UV irradiation of intensity L
M average logarithmic value of the number of viable bacteria for three photocatalytic treated
D
specimens, after being kept in a dark place
M average logarithmic value of the number of viable bacteria for three photocatalytic treated
L
specimens, after UV irradiation of intensity L
N number of viable bacteria with film cover method
P bacteria concentration
D dilution factor
F
R photocatalyst antibacterial activity value for film cover method, after irradiation at a con-
L
stant intensity L
ΔR photocatalyst antibacterial activity value with UV irradiation for film cover method
S photocatalyst antibacterial activity value for glass cover method, after UV irradiation of in-
L
tensity L
ΔS photocatalyst antibacterial activity value with UV irradiation for glass cover method
V volume of soybean casein digest broth with lecithin and polysorbate 80 medium for washout
Z average number of colonies in two Petri dishes
5 Principle
This document is for the development, comparison, quality assurance, characterization, reliability
and design data generation of photocatalytic materials. The method is used to obtain the antibacterial
activity of photocatalytic materials by the contact of a specimen with bacteria, under UV light
irradiation. The film cover method is available for flat sheet, board or plate-shaped materials. To avoid
warpage in the cloths or textiles, the glass cover method is available for the cloths or textiles.
The specimen is laid in a Petri dish and the bacterial suspension is dripped onto the specimen. Then
the cover film or glass is placed on the suspension and the moisture conservation glass is placed on
top of the Petri dish. The Petri dish containing the specimen is exposed to light. After exposure, the
test bacteria are washed out of the specimen and the cover film or glass. This washout suspension is
measured by the viable bacterial count method. The results obtained are compared with those obtained
© ISO 2019 – All rights reserved 3
---------------------- Page: 10 ----------------------
ISO 27447:2019(E)
from inoculated specimens of non-photocatalytic treated material exposed to UV irradiation under
identical conditions to the treated material, and to those obtained from inoculated specimens of both
photocatalytic treated and non-treated material kept in the dark for the same period of time.
6 Materials
6.1 Bacteria used and preparation for tests
6.1.1 Film cover method
a) Staphylococcus aureus
b) Escherichia coli
6.1.2 Glass cover method
a) Staphylococcus aureus
b) Klebsiella pneumoniae
6.1.3 Bacteria preparation
The bacteria strains to be used in the test are equivalent to those described in Table 1 and are stored by
entities that are registered under the World Federation for Culture Collections or the Japan Society for
Culture Collections.
Aseptic manipulations using microorganisms can be performed in an adequate safety cabinet. Inoculate
each strain into a slant culture medium (nutrient agar medium), incubate for 16 h to 24 h at 37 °C ± 1 °C,
and then store in a refrigerator at 5 °C to 10 °C. Repeat subcultures within 1 month by replicating this
process. The maximum number of subcultures from the original strain transferred by culture collection
is 10 times. In the case of bacteria stored in a deep freezer, the maximum number of subcultures from
the original strain transferred by culture collection is 10. The slant culture shall not be used for further
storing after 1 month.
NOTE If necessary, additional tests with other bacteria can be carried out.
Table 1 — Bacteria strains to be used in test
Bacteria species Strain number Organization for the collection
Staphylococcus aureus ATCC 6538P American Type Culture Collection
DSM 346 German Collection of Microorganisms and
Cell Cultures (DSMZ)
NBRC 12732 NITE Biological Resource Center
Escherichia coli ATCC 8739 American Type Culture Collection
DSM 1576 German Collection of Microorganisms and
Cell Cultures (DSMZ)
NBRC 3972 NITE Biological Resource Center
Klebsiella pneumoniae ATCC 4352 American Type Culture Collection
DSM 789 German Collection of Microorganisms and
Cell Cultures (DSMZ)
NBRC 13277 NITE Biological Resource Center
4 © ISO 2019 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 27447:2019(E)
6.2 Chemicals and implements
6.2.1 General
Commercial media with the components described as follows may be used.
The volume of prepared media may be adjusted in accordance with the number of specimens.
6.2.2 1/500 nutrient broth
For 1 000 ml of purified water, take 3,0 g meat extract, 10,0 g peptone and 5,0 g sodium chloride, put
them in a flask and dissolve them thoroughly. When the contents are thoroughly dissolved, use a solution
of sodium hydroxide or hydrochloric acid to bring the pH to (7,1 ± 0,1) at 25 °C. Dilute this medium
500 times using purified water, and set the pH to (7,0 ± 0,2) using hydrochloric acid solution or sodium
hydroxide solution. Sterilize in an autoclave at 121 °C ± 2 °C for at least 15 min. After preparation, if
1/500 nutrient broth is not used immediately, store it at 5 °C to 10 °C. Do not use 1/500 nutrient broth
made more than 1 week ago.
6.2.3 Nutrient broth
For 1 000 ml of purified water, take 3,0 g meat extract, 10,0 g peptone and 5,0 g sodium chloride,
put them in a flask and dissolve them thoroughly. When the contents are thoroughly dissolved, use a
solution of sodium hydroxide or hydrochloric acid to bring the pH to (7,1 ± 0,1) at 25 °C. If necessary,
dispense the contents in a test tube, add a cotton plug and sterilize in an autoclave (see 6.2.2). After
preparation, if the nutrient broth is not used immediately, store it at 5 °C to 10 °C. Do not use nutrient
broth made more than 1 month ago.
6.2.4 Nutrient agar
For 1 000 ml of purified water, take 3,0 g meat extract and 5,0 g peptone, put them in a flask and dissolve
them thoroughly. When the contents are thoroughly dissolved, use a solution of sodium hydroxide or
hydrochloric acid to bring the pH to (6,8 ± 0,2) at 25 °C. Add 15,0 g agar powder to this medium and
heat the flask in boiling water to dissolve agar powder thoroughly. Add a cotton plug and sterilize in an
autoclave (see 6.2.2). After preparation, if nutrient agar is not used immediately, store it at 5 °C to 10 °C.
Do not use nutrient agar made more than 1 month ago. Keep
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.