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                                                                Revised July 1, 2026

Continuous Antimicrobial Technology "AbedulAg+" for Infection Prevention

          ～Scientific Validation and Exploration of Technical Possibilities～         

                                                                                                                                                                            Continued Publication

​​​​How to Confront Infections Caused by Drug-Resistant Bacteria?

Infectious Diseases Are a Persistent Global Challenge

Infectious diseases have remained one of the greatest threats throughout human history. Although the eradication of smallpox, declared by the World Health Organization (WHO) in 1980, stands as one of humanity’s greatest public health achievements, infectious diseases remain far from being solved. As demonstrated by the COVID-19 pandemic, they continue to pose a serious global challenge.

Why Infectious Disease Control Is Difficult

1. Pathogens spread through human contact

  • Pathogens can be deposited on frequently touched surfaces such as doorknobs, handrails, switches, desks, and clothing.

  • Even after handwashing or disinfection, these surfaces can quickly become contaminated again.

2. The effects of disinfection are short-lived

  • Alcohol- and chlorine-based disinfectants effectively eliminate pathogens present at the time of application.

  • However, once new pathogens are deposited, the risk of infection immediately returns.

3. Pathogens can survive on various surfaces

  • Depending on the material and environmental conditions, bacteria and viruses may remain viable for several hours to several days.

  • Frequently touched environments therefore require continuous protection.

4. Complete disinfection is impractical

  • It is unrealistic to continuously disinfect every contact surface in hospitals, nursing homes, schools, public transportation, hotels, and households.

  • Labor and financial resources are inherently limited.

5. The growing threat of antimicrobial-resistant organisms

  • The increasing prevalence of antimicrobial-resistant pathogens, such as MRSA, has made infection prevention even more important.

  • Creating environments that actively prevent pathogen transmission is becoming increasingly essential.

6. Long-lasting protection is the key to prevention

  • Infection control cannot rely solely on one-time disinfection.

  • Ideally, contact surfaces themselves should possess durable antimicrobial and antiviral properties that remain effective over extended periods.

The fundamental challenge in infection control is that pathogens can repeatedly contaminate surfaces. Therefore, durable antimicrobial technologies are essential for reducing the continuous risk of contact transmission.

1. Why Did We Choose Textiles as Our Primary Target?

Why did we focus on durable antimicrobial technology?

In 2008, the U.S. Environmental Protection Agency (EPA) became the first regulatory agency to register copper and copper alloys as Continuous Antimicrobial Materials. This recognition led to large-scale clinical studies conducted in intensive care units (ICUs) in U.S. hospitals.

These studies demonstrated that continuously antimicrobial copper surfaces could significantly reduce healthcare-associated infections (HAIs).

A five-year multicenter clinical study conducted across several healthcare facilities confirmed that the installation of copper touch surfaces resulted in a statistically significant reduction in hospital-acquired infection rates. These findings attracted considerable attention because they provided scientific evidence that interrupting contact transmission can effectively reduce the spread of infectious diseases.

Limitations of Existing Copper-Based Technologies

Despite their proven effectiveness, copper-based antimicrobial products also revealed several practical limitations:

  • Surface discoloration and deterioration of appearance over time.

  • Limited versatility, restricting their range of applications.

  • Cost-performance challenges for widespread implementation.

Our Solution

To overcome these limitations, we developed AbedulAg+, a durable antimicrobial coating based on ceramic composite technology.

Unlike solid copper products, AbedulAg+ is a versatile coating system that can be applied to a wide variety of substrates, including textiles, providing long-lasting antimicrobial performance while maintaining practical usability.

Why Did We Select Textiles?

We selected textiles as our initial commercial target for three primary reasons:

  • Textiles are among the most frequently touched materials in everyday life, making them one of the highest-risk media for contact-based transmission of infectious diseases.

  • Textiles are routinely washed, allowing contaminated surfaces to be periodically cleaned and effectively reset while maintaining durable antimicrobial functionality.

  • Textile fibers possess a large effective surface area due to their twisted fiber structure, increasing the contact interface between microorganisms and the antimicrobial coating, thereby enhancing antimicrobial effectiveness.

2. Why Should We Focus on Antimicrobial-Resistant Pathogens?

Antimicrobial resistance (AMR) has become one of the most serious global public health threats of the 21st century.

Unlike conventional bacterial infections, infections caused by antimicrobial-resistant pathogens often cannot be effectively treated with existing antibiotics. Consequently, preventing infection has become far more important than treating it after it occurs.

1) The Effectiveness of Antibiotics Is Declining

The excessive and inappropriate use of antibiotics has accelerated the emergence of antimicrobial-resistant pathogens, including:

  • Methicillin-resistant Staphylococcus aureus (MRSA)

  • Vancomycin-resistant Enterococcus (VRE)

  • Carbapenem-resistant Enterobacterales (CRE)

  • Multidrug-resistant Pseudomonas aeruginosa

As antimicrobial resistance continues to increase, available treatment options are becoming increasingly limited.

2) Antimicrobial-Resistant Infections Increase Mortality and Healthcare Costs

Patients infected with antimicrobial-resistant pathogens generally experience:

  • Prolonged hospitalization

  • Increased healthcare costs

  • Higher mortality rates

  • Greater risk of hospital-acquired outbreaks

Healthcare-associated infections (HAIs) caused by resistant organisms impose a substantial burden on healthcare systems worldwide.

3) The Development of New Antibiotics Is Not Keeping Pace

Although antimicrobial-resistant pathogens continue to evolve, the development of new antibiotics has slowed considerably over the past several decades.

As a result, preventing infection before it occurs has become a global priority.

4) Preventing Transmission Is More Effective Than Treating Infection

Many antimicrobial-resistant pathogens are transmitted through contaminated hands and frequently touched surfaces.

Reducing environmental microbial contamination can interrupt contact transmission before infection occurs.

Therefore, continuously antimicrobial surfaces can serve as an effective complement to hand hygiene and routine disinfection.

5) Global Health Organizations Emphasize Infection Prevention

The World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and many national public health authorities recognize infection prevention as one of the most effective strategies for combating antimicrobial resistance.

Improved environmental hygiene and Continuous Antimicrobial Materials are increasingly regarded as essential components of comprehensive infection prevention programs.

6) Extensive Epidemiological Data Are Already Available

WHO Global Antimicrobial Resistance and Use Surveillance System (GLASS)

  • Surveillance data collected from 87 countries

  • Long-term monitoring of antimicrobial resistance trends

  • Detailed analyses by geographic region and pathogen species

Japan Nosocomial Infections Surveillance (JANIS)

  • Approximately 2,000 participating healthcare facilities

  • Real-time monitoring of antimicrobial resistance rates

  • Supports the development of predictive epidemiological models

7) The Market Opportunity Has Already Been Quantified

Economic Burden of Antimicrobial Resistance

  • United States: Additional healthcare costs of USD 20–35 billion per year

  • European Union: Approximately EUR 1.5 billion per year

  • Japan: Estimated JPY 800 billion per year

Economic Loss Due to Prolonged Hospitalization

  • MRSA infections: Average hospital stay extended by 7–10 days

  • CRE infections: Average hospital stay extended by 14–21 days

  • Estimated hospital cost: JPY 50,000–100,000 per patient per day

Healthcare Infrastructure (United States)

Healthcare Facilities

  • General hospitals: 6,090 (approximately 920,000 beds)

  • Specialty hospitals: 1,060 (approximately 110,000 beds)

  • Long-term care facilities: 15,600

  • Ambulatory surgery centers: 5,800

Annual Patient Volume

  • Hospital admissions: Approximately 36.5 million

  • Surgical procedures (including outpatient): Approximately 51 million

U.S. Infection Prevention and Control Market

  • Total market size (2023): USD 8.9 billion

  • Compound annual growth rate (CAGR): 8.2%

  • Projected market size (2028): USD 13.1 billion

Market Segments

  • Disinfection and sterilization: USD 3.8 billion (43%)

  • Personal protective equipment (PPE): USD 2.2 billion (25%)

  • Antimicrobial products: USD 1.8 billion (20%)

  • Other products and services: USD 1.1 billion (12%)

Quantified Market Opportunity in Japan

Healthcare Institutions

  • Approximately 8,300 hospitals

  • Approximately 1.5 million hospital beds

  • Approximately 500 million linen replacement cycles annually

  • Estimated market size: JPY 50–80 billion

Long-Term Care Facilities

  • Approximately 15,000 facilities

  • Approximately 950,000 residents

  • Infection risks comparable to healthcare institutions

  • Estimated market size: JPY 20–30 billion

8) The Economic Benefits of Infection Prevention Can Be Quantified

The economic impact of infection prevention can be estimated as:

Healthcare Cost Savings = Number of Prevented Infections × Additional Medical Cost per Infection

Example:

Prevention of 100 MRSA infections

Additional medical cost per infection: JPY 2 million

Estimated economic benefit:

100 × JPY 2 million = JPY 200 million in healthcare cost savings

 

Relevance to AbedulAg+

AbedulAg+ was developed based on this prevention-oriented approach to infection control.

Rather than relying on antibiotics after infection has occurred, AbedulAg+ continuously suppresses microbial contamination on textile surfaces, thereby reducing opportunities for contact transmission.

Furthermore, its antimicrobial activity is achieved through immobilized silver ions, representing a fundamentally different strategy from conventional antibiotic therapy. Instead of treating infected patients, AbedulAg+ is designed to prevent pathogen transmission before infection occurs.

As antimicrobial resistance continues to spread worldwide, durable antimicrobial technologies capable of reducing pathogen transmission prior to infection are expected to play an increasingly important role in future infection prevention strategies.

3. Current Status of Infections Caused by Antimicrobial-Resistant Pathogens

1) Overall Situation and Severity

Current Situation in the United States

Annual Burden (CDC 2022 Data)

  • Estimated annual cases of antimicrobial-resistant infections: Approximately 2.9 million

  • Annual deaths: Approximately 35,000

  • Additional healthcare costs: Approximately USD 4.5 billion per year

  • Average prolonged hospitalization: 6.4 additional days

Major Pathogens of Concern

  • Carbapenem-resistant Enterobacterales (CRE)

  • Methicillin-resistant Staphylococcus aureus (MRSA)

  • Vancomycin-resistant Enterococcus (VRE)

  • Clostridioides difficile (formerly Clostridium difficile)

  • Drug-resistant Mycobacterium tuberculosis

Epidemiological Situation (CDC 2019 Antibiotic Resistance Threats Report)

Urgent Threats

  • Carbapenem-resistant Acinetobacter: 8,500 cases/year

  • Candida auris: 1,150 cases/year

  • Carbapenem-resistant Enterobacterales (CRE): 13,100 cases/year

  • Clostridioides difficile: 223,900 cases/year (the largest single threat)

  • Drug-resistant Neisseria gonorrhoeae: 550,000 cases/year

Serious Threats

  • MRSA: 323,700 cases/year

  • VRE: 54,500 cases/year

  • ESBL-producing Enterobacterales: 197,400 cases/year

Total estimated disease burden: More than 2.8 million antimicrobial-resistant infections annually.

Economic Burden

Direct Healthcare Costs

  • Total annual healthcare costs: USD 28.6 billion

  • Average additional medical cost per infection: USD 18,588

  • Average additional ICU stay: 6.4 days

  • Average additional total hospitalization: 12.7 days

Indirect Economic Losses

  • Productivity loss: USD 35 billion per year

  • Premature mortality: USD 9 billion per year

  • Total annual economic loss: More than USD 100 billion

Current Situation in Japan

Annual Burden (National Institute of Infectious Diseases, 2023)

  • Estimated annual antimicrobial-resistant infections: Approximately 80,000

  • Annual deaths: Approximately 8,000

  • Additional healthcare costs: Approximately JPY 180 billion

  • Average prolonged hospitalization: 4.1 additional days

Major Pathogens of Concern

  • MRSA

  • ESBL-producing Enterobacterales

  • Carbapenem-resistant organisms

  • Fluoroquinolone-resistant bacteria

  • Multidrug-resistant tuberculosis

2) Current Status of Healthcare-Associated Infections (HAIs)

Healthcare-Associated Infections in the United States

Incidence Rates (NHSN 2022 Data)

  • ICU-associated infections: 1.2–3.8 per 1,000 patient-days

  • Surgical site infections (SSI): 0.6–3.4% (depending on the surgical procedure)

  • Central line-associated bloodstream infections (CLABSI): 0.8 per 1,000 catheter-days

  • Ventilator-associated pneumonia (VAP): 0.9 per 1,000 ventilator-days

Antimicrobial-Resistant Organisms in HAIs

  • Approximately 26% of all healthcare-associated infections involve antimicrobial-resistant pathogens.

  • In ICUs, 40–65% of HAIs are caused by resistant organisms.

  • Colonization rates in long-term care facilities are approximately 15–20%.

Healthcare-Associated Infections in Japan

Incidence Rates (JANIS 2023 Data)

  • ICU-associated infections: 0.8–2.1 per 1,000 patient-days

  • Surgical site infections (SSI): 0.4–2.8%

  • Central line-associated bloodstream infections (CLABSI): 0.5 per 1,000 catheter-days

  • Ventilator-associated pneumonia (VAP): 0.6 per 1,000 ventilator-days

Antimicrobial-Resistant Organisms in HAIs

  • Approximately 18% of all healthcare-associated infections involve antimicrobial-resistant pathogens.

  • In ICUs, 25–35% of infections are caused by resistant organisms.

  • Colonization rates in long-term care facilities are approximately 8–12%.

What Does "0.8–2.1 ICU-Associated Infections per 1,000 Patient-Days" Mean?

Patient-days are a standard epidemiological unit used in healthcare statistics to represent the total number of hospitalized patient days.

Examples include:

  • One patient hospitalized for one day = 1 patient-day

  • Ten patients hospitalized for one day each = 10 patient-days

  • One patient hospitalized for ten days = 10 patient-days

Interpretation of the Incidence Rate

An ICU-associated infection rate of 0.8–2.1 per 1,000 patient-days means that:

  • In an intensive care unit (ICU),

  • For every 1,000 patient-days of hospitalization,

  • Between 0.8 and 2.1 healthcare-associated infections are expected to occur.

Practical Examples

Example 1

A 20-bed ICU operates at full occupancy for 30 days.

  • Total patient-days = 20 beds × 30 days = 600 patient-days

  • Expected number of infections:

600 × (0.8–2.1) / 1,000 = 0.48–1.26 infections

Example 2

One hundred patients each remain in the ICU for an average of 10 days.

  • Total patient-days = 100 × 10 = 1,000 patient-days

  • Expected number of infections:

1,000 × (0.8–2.1) / 1,000 = 0.8–2.1 infections

Importance in Healthcare Statistics

The patient-day–based infection rate is an internationally standardized epidemiological indicator widely used to:

  • Evaluate the effectiveness of infection prevention and control programs,

  • Compare infection rates among healthcare institutions,

  • Monitor temporal trends in healthcare-associated infections, and

  • Benchmark hospital performance for quality improvement initiatives.

4. Why Are Infectious Diseases Considered a Perpetual Challenge for Humanity?

Infectious diseases are considered a perpetual challenge for humanity not simply because pathogens exist, but because pathogens and humans are engaged in an endless evolutionary "arms race," continually adapting to one another.

Why Are Infectious Diseases a Perpetual Challenge?

Infectious diseases have accompanied humanity throughout history and continue to pose a major global threat despite remarkable advances in medicine, public health, and sanitation.

In 1980, the World Health Organization (WHO) declared the global eradication of smallpox. This remains the only human infectious disease to have been completely eradicated and represents one of the greatest achievements in public health.

Nevertheless, new infectious diseases have continued to emerge, including:

  • HIV/AIDS

  • Severe Acute Respiratory Syndrome (SARS)

  • Pandemic Influenza (H1N1)

  • Middle East Respiratory Syndrome (MERS)

  • Coronavirus Disease 2019 (COVID-19)

  • Avian Influenza (H5N1 and H7N9)

  • Mpox

Furthermore, the rapid spread of antimicrobial resistance (AMR) has resulted in an increasing number of infections that are difficult or impossible to treat with existing antibiotics.

The persistence of infectious diseases can be attributed to several fundamental factors.

1) Pathogens Continuously Evolve

Bacteria and viruses constantly undergo genetic mutations, enabling them to adapt to human immune defenses and medical interventions.

As a result, new variants and antimicrobial-resistant pathogens are expected to continue emerging.

2) Human Exposure to Pathogens Is Unavoidable

People are continuously exposed to pathogens through contact with contaminated surfaces and interactions with other individuals in everyday life.

As long as human society exists, it is impossible to completely eliminate contact transmission or respiratory transmission.

3) Globalization Accelerates Disease Spread

Modern air travel and international trade allow infectious diseases to spread across the world within days.

The COVID-19 pandemic clearly demonstrated how rapidly a local outbreak can become a global public health emergency.

4) New Infectious Diseases Continue to Emerge from Animals

Many recently emerging infectious diseases are zoonotic diseases, transmitted from animals to humans.

Continued human interaction with wildlife and ongoing environmental changes increase the likelihood that novel pathogens will continue to enter human populations.

5) Antimicrobial Resistance Continues to Increase

The widespread use of antibiotics has accelerated the evolution of antimicrobial-resistant pathogens.

Meanwhile, the development of new antibiotics has not kept pace with the emergence of resistance.

6) Infection Prevention Depends on Human Behavior

Preventive measures such as hand hygiene, surface disinfection, and mask use remain effective only when they are consistently practiced.

In contrast, pathogens continue to survive and spread continuously, twenty-four hours a day.

7) Frequently Touched Surfaces Are Continuously Recontaminated

Frequently touched surfaces—including doorknobs, handrails, clothing, and bedding—can become recontaminated immediately after cleaning or disinfection.

Consequently, one-time disinfection alone is often insufficient to maintain a low risk of infection.

 

Conclusion

Infectious diseases are not a single problem that humanity can permanently eliminate. Rather, they represent a persistent global challenge arising from the continuous interaction among pathogen evolution, human society, and environmental change.

Accordingly, the focus of infection control is shifting from treatment alone toward preventive technologies that reduce the risk of infection before it occurs.

In particular, technologies that provide long-lasting antimicrobial and antiviral activity on frequently touched surfaces are expected to complement conventional hand hygiene and routine disinfection by continuously reducing the risk of pathogen transmission.

Against this background, AbedulAg+ was developed as a preventive infection control technology that continuously suppresses microbial contamination through immobilized silver ions on textile surfaces, thereby reducing the risk of contact transmission.

Because infectious diseases will remain a perpetual challenge for humanity, the societal importance of durable antimicrobial technologies such as AbedulAg+ is expected to continue growing in the years ahead.

5. A New Paradigm in Infection Prevention Introduced by the U.S. EPA's 2008 Registration of Copper Alloys

A major turning point in infection prevention occurred in 2008, when the U.S. Environmental Protection Agency (EPA) became the first regulatory authority to register copper alloys as continuously antimicrobial materials for public health applications.

This registration established a new paradigm in infection control. Rather than relying solely on periodic cleaning and disinfection, it formally recognized that surfaces themselves can continuously reduce microbial contamination between routine cleaning events, thereby helping to interrupt contact transmission.

Subsequent clinical studies conducted in U.S. hospitals demonstrated that installing high-touch copper surfaces significantly reduced microbial contamination and was associated with lower rates of healthcare-associated infections (HAIs). These studies are widely recognized as the first large-scale clinical evidence demonstrating that continuously antimicrobial surfaces can contribute to infection prevention under real-world healthcare conditions.

The EPA registration fundamentally transformed the concept of environmental infection control—from intermittent disinfection to continuous antimicrobial protection.

This paradigm shift stimulated the development of new durable antimicrobial technologies capable of providing long-lasting antimicrobial activity on a wide variety of substrate materials.

AbedulAg+ was developed based on this new concept of infection prevention. Unlike solid copper products, AbedulAg+ is a ceramic-based antimicrobial coating system that can be applied to a wide range of substrates, including textiles. By combining durable antimicrobial performance with excellent versatility, it offers broad application potential across diverse industries while maintaining long-lasting antimicrobial efficacy.

6. Advantages of Using Electrolytically Generated Silver Ions as the Active Antimicrobial Species

Unlike conventional silver-based antimicrobial technologies, AbedulAg+ utilizes electrolytically generated silver ions (Ag⁺) as the active antimicrobial species rather than silver nanoparticles or metallic silver. This approach provides several significant advantages.

1). Immediate Antimicrobial Activity

Silver ions (Ag⁺) are the biologically active form of silver responsible for antimicrobial activity.

Because AbedulAg+ directly employs Ag⁺ generated by electrolysis, antimicrobial activity is available immediately after coating, without requiring gradual oxidation of metallic silver or dissolution of silver nanoparticles.

2). No Need for Silver Nanoparticle Synthesis

Conventional silver-based antimicrobial coatings typically require:

  • Nanoparticle synthesis

  • Particle size control

  • Stabilizing agents

  • Dispersion processes

In contrast, electrolytically generated Ag⁺ can be incorporated directly into the ceramic coating, greatly simplifying the manufacturing process.

3). Reduced Environmental Release of Silver

Because Ag⁺ is immobilized within the TiO₂–ceramic matrix, silver release is extremely low.

This minimizes:

  • Environmental contamination

  • Human exposure

  • Loss of antimicrobial components during washing

ICP-MS measurements demonstrated silver release of ≤1 ppb after five days of water immersion, indicating excellent environmental stability.

4). Long-Term Antimicrobial Durability

The immobilized Ag⁺ remains associated with the ceramic interface instead of being rapidly consumed or washed away.

Consequently, AbedulAg+ maintains durable antimicrobial performance even after repeated laundering.

5). Efficient Utilization of Silver

Only a relatively small amount of silver is required because the biologically active Ag⁺ species are efficiently utilized at the surface where microorganisms come into contact.

This improves resource efficiency while maintaining high antimicrobial performance.

6). Simplified Manufacturing and Lower Production Cost

Electrolytic generation of silver ions eliminates multiple processing steps required for nanoparticle production.

The resulting process:

  • Reduces manufacturing complexity

  • Improves reproducibility

  • Lowers production costs

  • Facilitates industrial-scale manufacturing

7). Suitable for Continuous Antimicrobial Surfaces

Because the active silver species are immobilized rather than continuously released into the environment, the technology is particularly suitable for durable antimicrobial coatings designed for long-term surface protection.

This concept is consistent with the paradigm of continuous antimicrobial materials, where antimicrobial activity is maintained on the surface between routine cleaning events.

​

Relevance to AbedulAg+

The key innovation of AbedulAg+ is not simply the use of silver, but the combination of electrolytically generated Ag⁺ with a TiO₂–ceramic immobilization technology. This design enables long-lasting antimicrobial activity while minimizing silver release, simplifying manufacturing, and expanding applicability to textiles and other substrates.

7. Advantages of the Antimicrobial Mechanism of Silver Ions

Silver ions (Ag⁺) are among the most extensively studied inorganic antimicrobial agents and exhibit a broad-spectrum antimicrobial mechanism that differs fundamentally from conventional antibiotics and organic antimicrobial compounds.

1). Multi-Target Antimicrobial Mechanism

Unlike antibiotics, which typically act on a single biological target, silver ions simultaneously attack multiple cellular components, including:

  • Cell membranes

  • Cell walls

  • Membrane proteins

  • Respiratory enzymes

  • DNA and RNA

  • Ribosomes and protein synthesis systems

This multi-target mechanism makes it extremely difficult for microorganisms to develop resistance.

2). Broad-Spectrum Activity

Silver ions are effective against a wide range of microorganisms, including:

  • Gram-positive bacteria

  • Gram-negative bacteria

  • Drug-resistant bacteria (e.g., MRSA, VRE, and CRE)

  • Certain fungi

  • Some enveloped viruses

This broad antimicrobial spectrum makes silver ions suitable for diverse infection prevention applications.

3). Rapid Antimicrobial Action

Silver ions interact immediately with microbial cell surfaces upon contact.

They disrupt membrane integrity, inhibit essential metabolic enzymes, and interfere with nucleic acid function, ultimately leading to microbial death.

4). Low Potential for Resistance Development

Because silver ions affect multiple essential cellular pathways simultaneously, microorganisms have a much lower likelihood of developing resistance compared with conventional antibiotics that target a single biochemical pathway.

Although reduced susceptibility to silver has occasionally been reported under laboratory or clinical conditions, clinically significant silver resistance remains relatively uncommon compared with antibiotic resistance.

5). Non-Specific Mode of Action

Silver ions exert their antimicrobial activity through physicochemical interactions rather than receptor-specific biochemical inhibition.

Consequently, their efficacy is maintained against a wide variety of microbial species regardless of their antibiotic resistance profiles.

6). Continuous Surface Protection

When immobilized within a durable coating such as the TiO₂–ceramic matrix used in AbedulAg+, silver ions provide continuous antimicrobial protection directly at the surface where microbial contamination occurs.

This preventive strategy differs fundamentally from therapeutic antibiotics, which are administered only after infection has already occurred.

​

Relevance to AbedulAg+

The antimicrobial performance of AbedulAg+ is based on the unique combination of electrolytically generated silver ions and their immobilization within a TiO₂–ceramic matrix.

Rather than relying on the continuous release of antimicrobial agents, AbedulAg+ creates an interface where immobilized Ag⁺ species continuously suppress microbial contamination while minimizing silver release into the environment.

This interface-mediated antimicrobial mechanism enables durable antimicrobial performance, excellent environmental stability, and long-term protection against microbial contamination on textile surfaces.

８. Advantages of Silver Ion Antimicrobial Technology in Terms of Safety

Silver ions (Ag⁺) have been used safely in medical and healthcare applications for decades. Compared with many conventional antimicrobial agents, silver ions offer several important safety advantages, particularly when they are immobilized within a stable coating matrix.

1). Long History of Safe Medical Use

Silver-based antimicrobial materials have been widely used in healthcare for more than a century, including in:

  • Wound dressings

  • Burn treatments

  • Medical devices

  • Catheters

  • Surgical implants

  • Medical textiles

This extensive clinical experience has established silver as one of the most trusted inorganic antimicrobial agents.

2). Extremely Low Human Exposure When Immobilized

When silver ions are immobilized within a durable ceramic matrix, their release into the surrounding environment is minimized.

This significantly reduces:

  • Human exposure to silver

  • Skin absorption

  • Environmental contamination

In AbedulAg+, ICP-MS analysis demonstrated silver release of ≤1 ppb after five days of water immersion, indicating extremely low silver release under test conditions.

3). Non-Cytotoxic Performance

Biocompatibility testing of AbedulAg+ demonstrated:

  • No cytotoxic response in ISO 10993-5 testing using L929 fibroblast cells.

  • A Grade 0 cytotoxicity rating.

These results indicate excellent in vitro biocompatibility under the tested conditions.

4). No Evidence of Skin Irritation or Sensitization

According to biocompatibility evaluations performed in accordance with ISO 10993-10, AbedulAg+ showed:

  • No skin irritation (erythema)

  • No edema

  • No evidence of skin sensitization

These findings support its suitability for applications involving frequent human contact.

5). Reduced Environmental Impact

Because the antimicrobial silver species are immobilized rather than continuously released, silver consumption is minimized.

This contributes to:

  • Reduced environmental silver discharge

  • Improved sustainability

  • Long-term antimicrobial durability

6). Reduced Risk Compared with Conventional Chemical Disinfectants

Unlike alcohol-based disinfectants or chlorine-based disinfectants, immobilized silver-ion coatings:

  • Do not require repeated chemical application.

  • Do not evaporate after use.

  • Do not generate high local concentrations during routine use.

Instead, antimicrobial activity is maintained continuously on the treated surface.

7. Nanoparticle-Free Safety Design

Unlike many conventional silver-based antimicrobial technologies, AbedulAg+ does not use engineered silver nanoparticles. Instead, it utilizes electrolytically generated silver ions (Ag⁺) as the active antimicrobial species, providing a nanoparticle-free approach that aligns with the growing regulatory focus on nanomaterials in Europe and North America.

 

Relevance to AbedulAg+

AbedulAg+ combines electrolytically generated silver ions with a TiO₂–ceramic immobilization technology, enabling durable antimicrobial performance while maintaining extremely low silver release.

The combination of excellent biocompatibility, minimal environmental release, and long-lasting antimicrobial activity makes AbedulAg+ a promising platform for healthcare textiles and other applications requiring continuous antimicrobial protection.

９. Economic Advantages of Silver Ion Antimicrobial Technology

1) High Antimicrobial Efficacy at Very Low Concentrations (Reduced Material Costs)

Silver is well known for its oligodynamic effect, whereby extremely low concentrations of silver ions (Ag⁺) exhibit powerful antimicrobial activity. In other words, very small amounts of Ag⁺ are capable of inhibiting the growth of a broad range of microorganisms.

Representative target microorganisms include:

  • Escherichia coli

  • Staphylococcus aureus

  • Fungi

  • Numerous other bacteria and molds

Because of this unique property, silver ions provide excellent antimicrobial performance at ppm-level concentrations.

Economic advantages include:

  • Only ppm-level silver loading is required.

  • Material costs can be significantly reduced.

  • A single antimicrobial agent is effective against a broad spectrum of microorganisms.

Consequently, silver is widely regarded as one of the most cost-effective antimicrobial materials, providing broad-spectrum antimicrobial activity with only a minimal amount of active ingredient.

Initial Costs

  • Silver raw material: Relatively expensive per unit weight, but only a very small quantity is required.

  • Processing cost: Compatible with existing coating and material-processing equipment.

  • Quality control: Established analytical techniques, such as ICP and XPS, are readily available for quality assurance.

Operating Costs

Because silver-based antimicrobial materials provide long-lasting antimicrobial performance, operating costs can be substantially reduced.

  • Reprocessing frequency can be reduced to approximately 1/10 to 1/30 of that required for conventional disinfection.

  • Significant reduction in labor costs.

  • Minimal consumption of disinfectants and other consumables.

As a result, the Total Cost of Ownership (TCO) is expected to be reduced by approximately 50–80%.

2) Long-Lasting Antimicrobial Activity (Reduced Reprocessing Costs)

Conventional chemical disinfectants, such as:

  • Alcohol-based disinfectants

  • Sodium hypochlorite

  • Quaternary ammonium compounds

lose their antimicrobial effectiveness soon after drying.

In contrast, silver-based antimicrobial materials provide:

  • Continuous antimicrobial activity through surface-immobilized Ag⁺.

  • In some coating systems, antimicrobial performance that can be maintained for years.

Long-Term Economic Benefits

  • Reduced infection prevention and control costs.

  • Improved operational efficiency and productivity.

  • Enhanced product quality.

  • Increased brand value and customer confidence.

Typical Investment Performance

  • Return on Investment (ROI): 300–500% per year

  • Payback period: 6–12 months

  • Net Present Value (NPV): High

Such long-term durability can also provide a sustainable competitive advantage for businesses and healthcare facilities.

3) Reduced Maintenance Costs

Once incorporated into a material, silver-based antimicrobial technology requires little or no routine maintenance, such as:

  • Recleaning

  • Recoating

  • Repeated chemical disinfection

Typical applications include:

  • Antimicrobial textiles

  • Medical devices

  • HVAC air filters

  • Water treatment materials

In these applications, substantial reductions in operating and maintenance costs have been reported.

4) Broad Applicability Across Multiple Industries

Silver ion antimicrobial technology can be applied across a wide range of industries.

Major application areas include:

  • Medical devices

  • Water treatment

  • Air purification

  • Antimicrobial textiles

  • Food packaging

  • Building and construction materials

Because the same core technology can be deployed across multiple industries, research and development costs can be recovered more efficiently, providing significant industrial and commercial advantages.

5) Summary of the Economic Advantages of Silver Ion Antimicrobial Technology

From the perspective of materials science, the economic advantages of silver-based antimicrobial materials can be summarized by three key characteristics:

"Low Dose – Long Durability – Broad-Spectrum Antimicrobial Activity."

In other words, the outstanding cost-effectiveness of silver ion antimicrobial technology is derived from its ability to provide high antimicrobial efficacy with minimal silver usage, maintain long-lasting performance, and effectively suppress a broad spectrum of microorganisms. These three characteristics constitute the foundation of its economic superiority.

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10, Evaluation of Sustained Bactericidal Efficacy

1) Evaluation Method (Laundering Conditions)

Since there is no publicly standardized method for evaluating the durability of the bactericidal efficacy of antimicrobial textiles, a practical evaluation method was adopted in this study. Specifically, the durability of the bactericidal performance was assessed by determining the number of laundering cycles over which the bactericidal efficacy was maintained under repeated washing conditions.

The laundering procedure was conducted under the following conditions.

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SEK Mark Textile Product Laundering Method (Japan)　　　　　Document Control No.: JEC 326
Certification Department, Japan Textile Evaluation Technology Council (JTETC)

Scope of Application

This laundering method applies to textile products certified under the SEK Mark program that have been treated with antibacterial deodorizing finishes, antibacterial (control) finishes for general applications, photocatalytic antibacterial finishes, antifungal finishes, antiviral finishes, deodorizing finishes, photocatalytic deodorizing finishes, soil-release finishes, and ultraviolet (UV) shielding finishes.

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Laundering Conditions

1. Washing Machine

A fully automatic washing machine equivalent to the Type C standard washing machine (vertical-axis, top-loading pulsator type) specified in JIS L 1930 (Testing Methods for Domestic Laundering of Textiles) shall be used.

The washing machine used for this laundering test shall not be used for laundering textile products treated with finishes other than those covered by this evaluation.

2. Detergent

The JAFET Standard Formulated Detergent, containing polyoxyethylene alkyl ether and sodium alpha-olefin sulfonate, shall be used.

Note: The standard detergent specified in JIS L 1930 shall not be used.

3. Ballast Fabric

  1. Type III polyester ballast fabric specified in Annex H of JIS L 1930 (Testing Methods for Domestic Laundering of Textiles) shall be used.

    Ballast fabric previously used for laundering textile products treated with finishes other than those covered by this evaluation shall not be reused.

  2. When ballast fabric is reused, it shall be boiled and thoroughly rinsed after each laundering cycle.

4. Adjustment of Laundering Mechanical Action

When a fully automatic washing machine equivalent to the Type C standard washing machine (vertical-axis, top-loading pulsator type) is used, the laundering conditions shall conform to Laundering Method C4G specified in Annex F of JIS L 1930.

If the mechanical action of the washing machine does not satisfy the value specified below, the laundering mechanical action shall be adjusted in advance using the JIS L 1929 Washing Mechanical Action Test Cloth (WAT Cloth).

When adjustment is required, priority shall be given to adjusting the bath ratio by changing the amount of ballast fabric.

Mechanical action per laundering cycle:

ΔL* = 2.5 ± 0.5

Note 1: This value corresponds to the average laundering mechanical action of Laundering Method C4G specified in JIS L 1930.

5. Measurement of Laundering Mechanical Action Using WAT Cloth

The laundering mechanical action shall be measured in accordance with Annex A (Informative) of JIS L 1929, "Test Cloth (WAT Cloth) for Measuring Laundering Mechanical Action."

When the laundering conditions have been adjusted as described in Section 4, the measurement shall be carried out under the adjusted laundering conditions, including the modified bath ratio.

6. Laundering Procedure

  1. Laundering shall be performed under the laundering conditions adjusted as described in Section 4.

  2. The washing solution shall be prepared using the JAFET Standard Formulated Detergent at a concentration of 40 mL per 30 L of water.

  3. The laundering cycle shall be repeated until the required number of laundering cycles specified in Appendix 1 of the SEK Mark Certification Standards for Textile Products, corresponding to the applicable certification mark and product category, or the requested number of laundering cycles, has been completed.

Note 1: Tap water, well water, or industrial water may be used.

7. Drying Procedure

  1. Drying shall be carried out after completion of the prescribed laundering cycles.

  2. As a general rule, specimens shall be line-dried or flat-dried in the shade, avoiding direct sunlight. Mechanical drying equipment may also be used.

  3. When a tumble dryer or other drying equipment is used, textile products treated with finishes other than those covered by this evaluation shall not be dried together.

  4. The drying temperature shall not exceed 80°C.

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2). Evaluation of the number of times textiles are washed and the duration of the antibacterial effect.

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