Team:Stuttgart/Human Practices

Human Practices


"TAGC has a broad application in public places"

M. Teutsch

Paramedic, German Red Cross in Calw

"For medical applications TAGC has to proove efficient"

Dr. med. M. Orth

Head of laboratory medicine

"The field of biopolymers is very interesting"

Prof. Dr. C. Bonten

Head of department at the research institutes in the field of plastics engineering

We definitely know how we want to affect the world, how we want to find solutions and improvements for cases of infections and germ spreading. That's why we found and developed the idea of TAGC.

Human practices as an important part of iGEM considers opinions of people outside the lab, what they think of our project. Is it accepted? Is it a step in the right direction?

We want the public to think of TAGC as an useful innovation. For this we need further knowledge of the problem itself. What are first steps to prevent germ spreading? How can TAGC support the stop? For this reason we gained information in affected institutions: the Marienhospital and Katharinenhospital in Stuttgart. Furthermore, with Micheal Teutsch of the German Red Cross ambulance in Calw we considered the issue of TAGC application.

Besides that, we really want TAGC to be an actual consideration, to be a matter that works. Hence, the development and the progress of TAGC is a main point which needs to be matured. Human practices is an opportunity to affect these parts of our project. Further characterization of TAGC and manufacturing was discussed with Prof. Dr.-Ing. Christian Bonten and some of his colleagues.

How is the spread of germs handled in hospitals?

As a part of human practices, we aimed to gather information about the hygiene standards in general and about a possible medical application of TAGC. Therefore, we contacted associate professor Dr. Matthias Orth of the Marienhospital and the department for hospital hygiene of the Katharinenhospoital, both located in Stuttgart.

Due to the obtained information, we gained knowledge in two areas: clinical hygiene & present antimicrobial agents and requirements for innovative surface coatings like TAGC. Both hospitals agreed about following points.

Clinical hygiene and present antimicrobial agents

It’s not necessary for each surface to be sterile. A disinfecting cleaning needs to be conducted for surfaces which are mainly touched by hands (e.g. handles, toilets, handrails, elevator buttons, bed holms). Some antimicrobial agents like copper or silver evolve effects only after a couple of hours. So, potential pathogens can spread on minutely touched surfaces before antimicrobial effects show.

Moreover, risks for health and environment occur caused by possible uptake of nanoparticles of these heavy metals.

Requirements for innovative surface coatings

  • Withstand daily cleaning
  • Remain active after usage of disinfection agents, cleaning detergents containing aldehyds and acetic acid which is used against novo viruses
  • Avoidance of allergic reactions
  • Bear high resilience of surfaces
  • Show minimal activity for efficient reduction of cleaning frequency: quantity of bacteria needs to be decreased by factor 106
  • No detachment of nano particles

Is TAGC ideal in medical sectors?

Expert interview about disinfection and applications of surface coating

Michael Teutsch works as a paramedic at the ambulance station of the German Red Cross in Calw. Besides, he operates as disinfector and supervises cleaning as well as disinfection of ambulances and the station. Because of his great knowledge of aseptic and sterile surfaces especially in medical sectors we talked with him about hygiene, antimicrobial surfaces in general and about our project, The Anti Germ Coating (TAGC).

iGEM Stuttgart: What is done to prevent the spreading of germs at the ambulance station in Calw?

Teutsch: We act on a hygiene plan which prescribes which surface is to be cleaned with which frequency and which kind of detergent. It is valid for all surfaces in the ambulance station: the ones in ambulances and the ones in the station itself (e.g. floor, door handles, tables). Furthermore, arrangements for regeneration of uniforms and waste disposal are mentioned.

Mainly two different disinfecting agents are used which inactivate various bacteria and viruses.

How often do you use these methods? How is it supervised?

Basic cleaning takes place once a week. Then the whole station and ambulances are cleaned. After each transport of a patient cleaning of exposed surfaces occur. In case of an infection ride the ambulance is disinfected as well (editor’s note: An infection ride is defined as transport of patients who cause possible infectious material like blood, salivary or other excretions).

Besides that, annual surveillance is conducted via examining specimens in the laboratory. However, viruses are not detected with this method (editor’s note: Taking specimens is carried out by pressing culture media (mainly agar) on inspected surfaces. After incubation, quantity of bacteria colonies is examined).

What risks arise from improper cleaning of an infected surface?

Following patients and in addition treating staff might infect themselves. Even though it’s possible I’m not aware of cases where improper cleaning led to infection of patients.

Which advantages could offer an antimicrobial surface coating in your daily work life?

It reduces the frequency of disinfection of surfaces. Cleaning will still be necessary though. Moreover, such surfaces have to withstand mechanical stress and feature reduced abrasion.

Good point, what demands should such a surface coating meet?

It should be wipe- and washable. Beside decreased abrasion caused using common detergents mechanical stability and functional durability are desired. Due to permanent operation of the ambulances the surface is highly used which possibly results in regular reapplication of the coating. An environmentally friendly solution would be preferable too.

There are already approaches for antimicrobial coatings based on metals. Do you have experience with such surfaces? If so, what is your opinion?

I‘ve researched about some of these methods (titanium oxide, copper sulfate). These approaches seem promising. However, I wouldn‘t use current developments of these coatings.

What is the reason for not using them?

Well, water is not able to drain off these coatings. It won‘t affect small areas, but you can‘t turn an ambulance upside down so that accumulated water will run off. Furthermore, there are no immaculate validations of tested conditions.

Explaining the iGEM competition and our project to Mr. Teutsch.

What are advantages and possible applications for our coating?

Such a surface coating is applicable if it prevents germs from spreading. Though in medical fields it‘s critical because of often and intense usage of surfaces in ambulances. High abrasion would result in consequent reapplication of the coating.

But still for sanitary areas it might be ideal: sanitary rooms, hospitals, public spaces or door handles e.g. are not disinfected with such aggressive detergents like we use it here. So the coating doesn’t have to withstand it and there is no need for the same strong antimicrobial effects as in ambulances. The frequent occurrence of immune suppressed patients in ambulances and their resulting sensibility to pathogens result in the needs for high antimicrobial effect.

I can not imagine the usage in my own home. Each resident contains similar colon bacteria. Contact with pathogens isn‘t as contagious as with unknown people.

Could you sum up your thoughts of our antimicrobial coating?

The idea behind it is useful. Applications however might be rather in public than medical sectors. Therefore, further developments and maturation progresses are needed. The coating should possess long-term effects, withstand common detergents and mechanical abrasion.

Sounds like an valuation we can work with. Thank you very much!


How can TAGC development improve?

Expert interview about plastics engineering

In order to get some impulses concerning the production of our coating we met Prof. Dr.-Ing. Christian Bonten, head of the institute of Plastics Engineering of the University of Stuttgart, and some of his colleagues.

We explained them our project and the polymer we plan to produce. To give us further advice, it was essential for them to know something about the properties of the polymer.

For polymer characterization they asked us for kilograms of TAGC. We were really shocked about this amount because we were able to produce TAGC at a 1 gram scale to this time. The production in a large scale is really expensive due to the high amounts of ionic liquid. So we were able to give them only 20 mg for one basic test: the differential screening calorimetry (DSC). This analysis was conducted to identify the characteristics of our polymer.

Plastics are divided into three different classes: thermoplasts, duroplasts, and elastomers. The focus of the institute is the processing of thermoplastic polymers (by extrusion). Which means that they melt the polymer and shape it afterwards. The DSC analysis of TAGC showed that the polymer has no thermoplastic properties. Therefore, the institute was not able to help us and referred us to the field of chemical engineering and proposed us the method of liquid-liquid extraction.

Integrated Human Practices: How did the gathered information affect our project?

For fulfilling the requirements mentioned before, we tested the solubility and the withstand of TAGC to common used detergents. Alkaline conditions were examined in dish soap and 1 M NaOH. TAGC was soluble in NaOH. Besides, 100 % acetate acid and 10 % hydrochloric acid were tested for acid conditions. No solubility was observed under those conditions. So we verified TAGC as a possible application for public areas where no strong disinfected cleaning is needed. Since no abrasion occurred when the coating was wiped, we confirmed its washability.

To test TAGC as an application we tried different thicknesses of the polymer and placed it on a door handle to demonstrate its effect. An antimicrobial assay revealed the effects our TAGC induces. It was effective for E. coli, C. glutanicum, L. lactis and B. subtilis as well as for S. cerevisiae (see Demonstrate). In comparison to alternative approaches like copper and silver applications our TAGC is a considerable, eco-friendly possibility.