Phosphorescent hydrogels

INOR 309

Sreekar Marpu, sreekarmarpu@gmail.com1, Tong Cai, tong.cai@gmail.com2, Pankaj Sinha, ps0075@unt.edu1, Zhibing Hu, zbhu@unt.edu3, and Mohammad A. Omary, omary@unt.edu1. (1) Department of Chemistry, University of North Texas, Box 305070, Denton, TX 76203, (2) INEST post-doc. program, Philip Morris USA, Denton, TX 76201, (3) Department of Physics, University of North Texas, Denton, TX 76203
Stimuli-responsive hydrogels undergo large conformational changes only with small changes in the environment. Photosensitive phosphorescent hydrogel microspheres synthesized by incorporating an inorganic phosphor, [Au(TPPTS)3]Na8, into the polymer network of poly-N-isopropylacrylamide (PNIPAM)-co-allylamine and the resulting material exhibited sensitized Au-centered emission compared to that of the gold complex in pure water. These phosphorescent microspheres were further crosslinked by covalently bonding neighboring particles. The resulting hydrogels showed a remarkable temperature-dependent luminescence with full hysteresis upon reversible heating and cooling between the luminescent form at room temperature and the quenched form at body temperature. The stimuli-responsive behavior of these hydrogels remained unaltered even in presence of the gold luminophore. Phosphorescent hydrogels with longer lifetimes are preferred for various bio-medical applications over fluorescent hydrogels with shorter life-times known, albeit scarcely, in the literature. To our knowledge, the work herein represents the first example of a phosphorescent hydrogel.