A recent publication details a self-cleaning nanocrystal which can be coated onto clothe fibers. A recent article in Technology Review, Clothes that Clean Themselves, details the discovery.
Researchers at Monash University, in Victoria, Australia,
have found a way to coat fibers with titanium dioxide
nanocrystals, which break down food and dirt in sunlight. The
researchers, led by organic chemist and nanomaterials
researcher Walid Daoud, have made natural fibers such as
wool, silk, and hemp that will automatically remove food,
grime, and even red-wine stains when exposed to sunlight.
Daoud and his colleagues coat the fibers with a thin, invisible
layer of titanium dioxide nanoparticles. Titanium dioxide,
which is used in sunscreens, toothpaste, and paint, is a s
trong photocatalyst: in the presence of ultraviolet light and
water vapor, it forms hydroxyl radicals, which oxidize, or
decompose, organic matter. However, says Daoud, "these
nanocrystals cannot decompose wool and are harmless to
skin." Moreover, the coating does not change the look and
feel of the fabric.
The original publication appears in
Chemistry of Materials
Walid A. Daoud, S. K. Leung, W. S. Tung, J. H. Xin, K. Cheuk, and K. Qi. Self-Cleaning Keratins. Chem. Mater.; 2008; 20(4) pp 1242 - 1244; (Communication)
DOI:10.1021/cm702661k
Here is an image an caption from the aforementioned TR article...
Wine be gone: Wool fibers have to be chemically modified to receive a stable coating of titanium dioxide nanocrystals, which break down organic matter in sunlight. Red-wine stains do not leave uncoated fibers even after 20 hours (top right); unmodified nanocrystal-coated fibers show some stains (middle right). The stain is almost gone in chemically modified fibers because of the firmly attached nanocrystals (bottom right).
Original Credit: American Chemical Society