The key active ingredients used by the textile antimicrobial industry have not changed significantly in the last twenty five years. The existing competitive or old compositions are usually metallic or phenol based. Others have entered the market with slight modifications of old organosilane technologies that on some substrates extend the life of their products but clearly fail to deal with all of the other problems that are inherent in the active ingredients list such as toxicity, leaching, etc.
Singlotech’s non-toxic dye is applied in a totally aqueous medium and once deposited into the textile fabric it becomes water insoluble and will not leach out. It then generates an inexhaustible supply of singlet oxygen in the presence of light to eliminate any bacteria present. Furthermore, because the dye works catalytically, only a trace amount is necessary for efficient microbicidal action.
A good example of an application that could benefit from this novel technology would be the labelling of nano-sized reporter/signal beads or particles with fluorescent dyes for medical diagnostic assays. Maintaining the surface integrity of these labels is critical to the ultra-sensitivity of such assays and the diagnostics industry recognises the susceptibility of these extremely fragile surfaces to organic solvents employed under the current conditions.
Because no organic solvents are employed using this new technology there is no toxic waste to be disposed of, the result of “green” chemistry that is one hundred percent eco-friendly.
The deposition of dyes that generate reactive oxygen species to kill bacteria using our novel technology is especially applicable for coating surfaces as varied as plastics, glass, ceramics and textiles. Not only is a very evenly impregnated coat obtained but no harmful solvents are utilised in the coating process.
Photodynamic therapy (PDT) is a rapidly growing medical application in which fluorescent dyes are used as photosensitisers that selectively aggregate in diseased organic tissues, particularly cancerous or fibrous tumours.
These tumours are then irradiated with available light sources that cause the photosensitisers to fluoresce and, in the process, generate reactive oxygen species, such as singlet oxygen, which is toxic to the tumour cells and kills them. Normally, the photosensitizers currently used must be irreversibly and chemically altered to render them water soluble for adbsorbtion into the blood stream and transport to the site of the tumour. However, this property is not so advantageous for efficient adsorbtion of the photosensitizers across the cell membranes when they reach the tumour cells.
Singlotech’s novel technology eliminates this irreversible process, allowing for an enhanced, non-immunogenic, transiently water soluble transport medium. The net result is greatly increased photosensitiser accumulation in the tumour cells, resulting in increased generation of reactive oxygen species on exposure to the light source and thus far more efficient tumour cell destruction. Researchers world-wide are now focusing on PDT as a valuable therapy, not just for the treatment of skin cancer but for the treatment of breast and bladder cancer, heart disease, the prevention of restenosis following angioplasty, age-related macular degeneration, Barrett’s oesophagus, nail fungus, warts, acne, psoriasis and other skin diseases.
Currently, the major use of photodynamic antimicrobial chemotherapy therapy is in the disinfection of blood products, particularly for viral inactivation. We believe our technology to be highly relevant to this field since it affords a non-immunogenic environment for the photosensitiser and generation of reactive oxygen species.
Water Treatment – Decontamination
It is estimated that one sixth of the world’s population lack safe drinking water and that in developing countries alone, microorganisms are responsible for two and a half million deaths a year. Photodynamic water treatment (using sunlight along with artificial light sources) has the potential to become a viable process for water purification instead of chlorine disinfection. Singlotech’s novel technology affords a simple way to deposit dyes that generate reactive oxygen species and kill microorganisms in the prescence of sunlight. The photosensitised detoxification of industrial and urban wastewaters using sunlight is already gaining increasing interest because the use of solar energy in the treatment of wastewater could be an economical “green” solution to a difficult environmental problem.