Antimicrobial Medical Textiles

Antimicrobial Substances and Their Effect

Many antimicrobial agents used in the textile industry are known from the food stuff and cosmetics sector. These substances are incorporated with textile substrates comparatively at lower concentrations. It must be ensured that these substances are not only permanently effective but also that they are compatible with skin and the environment.

A wide palette of antimicrobial compounds is now in use but differ in their mode of action. The following list demonstrates the polyvalent effect of the various antimicrobial substances:

Materials with active finishes contain specific active antimicrobial substances, which act upon micro-organisms either on the cell, during the metabolism or within the core substance (genome). However, due to the very specific nature of their effect, it is important to make a clear distinction between antibiotics and other active substances which have abroad range of uses.

Oxidizing agents such as aldehydes, halogens and proxy compounds attack the cell membrane, get into the cytoplasm and affect the enzymes of the microorga-nisms.

Coagulants, primarily alcohols irreversibly denature the protein structures.

Redical formers like halogens, isothiazones and peroxo compounds are highly reactive due to the presence of free electrons. These compounds virtually react with all organic structures in particular oxidizing thiols in amino acids. Even at the lowest level of concentrations, these substances pose particular risk to nucleic acids by triggering mutations and dimerization.

One of the most durable type of antimicrobial products is based on a diphenyl ether (bis-phenyl) derivative known as either 2, 4, 4′-trichloro-2′ hydroxy dipenyl ether or 5-chloro-2-(2, 4-dichloro phenoxyl) phenol. Triclosan products have been used for more than 25 years in hospitals and personal care products such as antimicrobial soap, toothpaste and deodorants.

Triclosan inhibits growth of microorganisms by using a electro chemical mode of action to penetrate and disrupt their cell walls. When the cell walls are penetrated, leackage of metabolites occurs and other cell functions are disabled, thereby preventing the organism from functioning or reproducing. The Triclosan when incorporated within a polymer migrates to the surface, where it is bound. Because, it is not water-soluble, it does not leach out, and it continuously inhibits the growth of bacteria in contact with the surface using barrier or blocking action.

Quaternary ammonium compounds, biguanides, amines and glucopro-tamine show poly cationic, porous and absorbent properties. Fibres finished with these substances bind micro-organisms to their cell membrane and disrupt the lipo poly saccharide structure resulting in the breakdown of the cell.  Complexing metallic compounds based on metals like cadmium, silver, copper and mercury cause inhibition of the active enzyme centers (inhibition of metabolism). Amongst these, the silver compounds are very popular and already been used in the preparation of antimicrobial drinking water.

Chitosan is an effective natural antimicrobial agent derived from Chitin, a major component in crustacean shells. Coatings of Chitosan on conventional fibres appear to be the more realistic prospect since; they do not provoke an immunological response. Fibres made from Chitosan are also available in the market place.

Natural herbal products can be used for antimicrobial finishes since; there is a tremendous source of medicinal plants with antimicrobial composition to be the effective candidates in bringing out herbal textiles.