Turn on fluorometric b carotene assay based on competitive host guest interaction between rhodamine 6G and b carotene with a graphene oxide functionalized with a b cyclodextrin modified polyethyleneimine
AbstractThe authors describe a "turn on" fluorometric method for determination of b carotene. It is based on competitive host guest interaction between rhodamine 6G (R6G) and b carotene and graphene oxide nanoparticles that were functionalized with b cyclodextrin (b CD) modified polyethylenimine (b CD PEI GO) On addition of R6G to a solution of b CD PEI GO, its fluorescence is quenched because of the inclusion of R6G into the b CD moiety. Both Forster resonance energy transfer and electron transfer are likely to occur. On further addition of a sample containing b carotene, it will replace R6G in the cavity, thereby releasing R6G to the bulk solution. This is due to the stronger affinity of b carotene for b CD in the complex, but also because of repulsion between the positively charged b CD PEI GO complex and the positively charged R6G dye. The displacement of R6G by b carotene leads to fluorescence recovery whose efficiency (expressed as F/F0) is related to the b carotene concentration in the range from 0.1 to 4.0 mmolL 1. The detection limit for b carotene is 5.4 nmolL 1 which is lower than that of any other optical method. Graphical abstractGraphene oxide hybrid materials can quench the fluorescence of rhodamine 6G by surface energy transfer. The addition of b carotene to the solution results in the recovery of the fluorescence of the system owing to the release of rhodamine 6G from the graphene oxide hybrid materials.
Microchimica Acta