To do this, they doped some TiO2 with nitrogen, which had been previously shown to work as a light-activated catalyst in visible light. They developed a new method to put this nanoparticle solution in liquid form, dunked cotton in it for one minute, then pressed the cotton, dried it and re-rinsed it. Then they added some silver iodide nanoparticles, which were intended to improve the fabric's overall light sensitivity. The researchers stained the fabric with orange dye, and then exposed it to sunlight. The cotton broke down the orange, and also sterilized bacteria.