In recent years, with the improvement of quality of life, there has been an increasing interest in aseptic

condition in various fields, including the residential environment. This review outlines the research and

development status of antimicrobial and antiviral materials that have been undertaken to date. Then, the

antimicrobial and antiviral material, such as ABCoat consisting of metallic nanocolloids, which we have been

developing with focusing on safety is presented.

ABCoat is an aqueous dispersion in which platinum and silver are nanocolloidated, and the constituent

concentration of the particles is 0.1wt% or less, and the average particle diameter is about 100nm. By

supporting this dispersion on various materials, the Ag+ and Pt4+ derived from metal nanocolloids don’t elute

and represents antimicrobial performance. In a short time, ABCoat reduces microbes such as Escherichia

coli, Staphylococcus aureus, herpes simplex viruses, and adenoviruses. This mechanism of action may be

inactivation by adsorption of nanoparticles to surface of bacteria and viruses.

A purpose of this treatise is introduction of ε-Poly-L-lysine（ ε-polylysine）, which is homo polymer of L-lysine.

It is produced by fermentation method in aerobic culture with Streptomyces albulus. Chemical structure

of ε-polylysine is too unique, it is polymerized ε-position amino group and α-position carboxyl group in Llysine

by amide bond, that structure resembles nylon 6. α-Position amino groups in ε-polylysine charges with

a cationic charge in water under pH 9, it behaves as a cationic polymer. This cationic charge provides variety

of effect, such as antimicrobial effect, adsorption or dispersion effect for electric charged components, and so

on.

ε-Polylysine has been approved as a natural origin food preservative in Japan since 1989, also has been approved

in south Korea, the United States, and China. In addition, it is used as not only food preservative but

also as an ingredient for cosmetics and chemicals.

ε-Polylysine inhibit various microorganisms at low concentration, and it provides synergistic effect with other

antimicrobial agents, such as alcohol, organic acids, chelating agents, and so on. Recently, it has found out

that combination of ε-polylysine and natto-extract（ NAP） provides inhibition effect of Feline calicivirus（ FCV）

With increasing of awareness in cleanliness and sanitation, it is a great interest in the relation of

microorganisms or viruses with humans, such as raising awareness of health promotion like improvement

of intestinal flora, and of crisis over food poisoning accidents and infectious diseases. These will be able

to be caught as an increase of the necessity of the microbial control in the living environment. This paper

explains the characteristics of microorganism cells and viruses and their growth environment, as well as the

characteristics of biofilms, populations of microbial cells, and reports some control methods for microbial cells

and biofilms.

In this paper, the possibility of COVID-19 infection routes analyzed from the viewpoint of fine particle

technology was introduced. Large saliva droplets containing a large amount of virus fall in a short time, and the

contaminated surfaces may cause the source of fomite transmission. However, infection does not occur just by

attaching the virus on our hands. Therefore, hand washing helps prevent infection. In contrast, the amount of

viral load in small droplets that cause aerosol infection is only 0.01-0.001 wt％ of the total viral load in saliva.

Therefore, wearing a mask is very effective in preventing infection. However, depending on contact time and

number of people, accumulation of aerosols in space can cause aerosol infection. Therefore, it is important to

properly ventilate the space. In addition, since highly infectious mutant COVID-19 strains may enhance aerosol

infection, medical knowledge is desired.