Carotenoids in sol-gels: Incorporation, stability, and sensitivity to oxidant and acid

It is shown in this paper that carotenoids can be incorporated into sol-gel s and can be evenly distributed by using appropriate amounts of organic sol vents (e.g., EtOH and acetone). Some carotenoids (e.g., 8'-apo-beta -carote n-8'-al) are relatively stable in sol-gels. The studied sol-gel matrix has no obvious effect on the stability of carotenoids. Carotenoids in sol-gels can still react with an oxidant and acid (FeCl3 and H2SO4, respectively, in our experiments) that are present in the contacting aqueous solutions. Thi s observation suggests that one may take advantage of the visible absorptio n of carotenoids and the solid and transparent character of sol-gels to bui ld sensors for oxidants and acids using the carotenoid-containing sol-gels.