Cellulose acetate fibers with fluorescing nanoparticles for anti-counterfeiting and pH-sensing applications

Abstract

Fluorescent silica nanoparticles, Cornell dots (C dots), were incorporated into electrospun cellulose acetate (CA) fibers. Two types of C dots were used in this study. The first type was comprised of a fluorescent dye-containing silica core surrounded by a silica shell. These nanoparticles fluoresce at 572 nm when exposed to 541 nm light. Increasing C dot loading in the spinning dope above 10% w/w did not result in an increase in C dot content within the final fibers. Scanning electron microscopy indicated that the nanoparticle incorporation had very little effect on the fiber morphology. The mechanical properties of the electrospun fabrics were not negatively affected by C dot addition, even though final loading constituted nearly one-third of the weight of the fibers. A second type of C dots, with both a fluorescent core and a pH-sensitive shell, were also incorporated in CA fibers. These C dots fluoresce at both 572 nm as described above, and at 518 nm, when exposed to 488 nm light. Fluorescence intensity at 541 nm increased with increasing pH. For both nanoparticle-incorporated fabrics, the resulting fibers are white under ambient lighting, and fluoresce at their given wavelengths of light.