As part of an AiF research project (AiF no. N 17407), scientists from the Hohenstein Institute in Bönnigheim, Germany, have for the first time developed a textile finish with both an antiviral and an antibacterial function. The technology can be used for products in hospitals and elsewhere to interrupt chains of infection.
Most infection-induced respiratory problems are caused by viruses. For example, the respiratory syncytial virus, a pathogen belonging to the family of paramyxoviruses, can cause infections of the upper respiratory tract in the form of colds, coughs, acute bronchitis or even pneumonia, particularly in small children. At the start of winter, the rate of infections in child day care centres and nurseries regularly increases. Diarrhoea caused by noroviruses and rotaviruses as well as bacterial infections of the respiratory tract and the alimentary tract, on the other hand, are ‘in season’ all year round.
To avoid droplet and smear infections as far as possible, hygienic hands, textiles and surfaces are of paramount importance. The essential factor in avoiding or limiting the spread of disease in healthcare facilities is regular, thorough hand-washing by both visitors and carers.
However, textiles can also play a part in spreading pathogens. Viruses do not have their own metabolism and can therefore survive for only a limited time outside a host and, unlike bacteria, do not multiply there. However, as studies have impressively documented, textiles that are in regular contact with hands have been proven to contribute to the spread of viruses (Sauver et al., 1998).
In a scientific examination, clothes as well as domestic and hospital textiles in the form of bed linen, towels, kitchen towels and so on are, alongside hands, an important potential transmission route for viruses.
Surfaces of all kinds, which can also be contaminated by viruses and bacteria via the hands or air, are the third key transmission route for viruses. One important element in preventing infection is therefore the cleaning of surfaces. Hohenstein scientists are investigating these factors in their current research project.
The test design includes cleaning cloths in which, for the first time, antiviral and antibacterial effectiveness have been combined in one functional textile finish. ‘Over the long term, we are interested in finding out whether the risk of infection – that is to say the spread of germs from person to person – can be reduced by using biofunctional textiles in the future,’ says Professor Höfer, head of the hygiene, environment and medicine department.
To achieve this goal, various organic and inorganic colloidal or nanoparticle copper compounds and copper complexes were first applied in a sol-gel process. The effectiveness of the textile microfibre substrate was optimised using various application techniques such as foulard or spray methods. The inactivation of the test viruses was significant, was retained over 15 washing cycles and was at the same time abrasion-resistant.
A second alternative antiviral finish of microfibre cloths was achieved by finishing with copper pigments in a high-temperature exhaust process. In a similar way to dying with dispersion dyes, the dispersed copper pigments were incorporated in the fibres in a slightly acid environment. In a second step, fixing was carried out using a polymer binding agent in a cold padding process to protect the copper particles against mechanical abrasion. These copper finishes also produced good evenness, but there was a slight green tone compared with the originally lighter fabric colour. All samples passed the laboratory tests on skin-friendliness.
Colour differences in cleaning cloths made of microfibres before and after finishing with copper pigments
©Hohenstein Institute
The effectiveness tests under realistic conditions were carried out on different surfaces, such as glass, stainless steel or wood, which were contaminated with viruses and wiped with the finished cleaning cloths. The bacterial virus MS2, a non-pathogenic surrogate virus, which due to its structure and environmental stability is comparable to clinically relevant viruses such as novovirus, poliovirus, hepatitis A or enteroviruses, was used as the test virus. The finished microfibre cloths absorbed 91% of the applied viruses.
At the same time, the virus concentration in the cloth was reduced by approximately 90%. Effectiveness tests against bacteria and mould were also carried out in accordance with standards DIN EN ISO 20743 and EN 14119. With this test set-up, the finishes were optimised in a targeted manner. The research project reveals that antiviral cleaning cloths provide an efficient hygienic effect and can help to reduce the germ transfer rate, e.g. of pathogens in nurseries and child day care centres. However, this new functionalisation could be of interest in the domestic environment, in hospitals, old people’s homes, care homes and in communal facilities (e.g. canteens), and in protective clothing for the fire brigade, emergency services and military.