Two-photon fluorescence probe for quantification of cyclosporine.

A novel ratiometric fluorescent sensor was fabricated for the fast and facile determination of cyclosporine A (CsA). Due to the narrow therapeutic index of CsA, its desired therapeutic effects are evident within a limited range of blood concentration, indicating the fundamental role of therapeutic drug monitoring in CsA pharmacological response. In this study, a two-photon fluorescence probe based on the zeolitic imidazolate framework (ZIF-8) and norepinephrine-capped silver nanoparticles (AgNPs@NE) was employed for the quantification of the CsA in human plasma samples. In the presence of CsA, the fluorescent emission intensity of ZIF-8-AgNPs@NE was quenched. Under the optimum conditions, the proposed probe determines CsA in plasma samples in two linear ranges of 0.01 to 0.5 μg mL and 0.5 to 10 μg mL. The developed probe demonstrates the advantages of a facile and fast platform with limit of detection as low as 0.007 μg mL. At last, this method was applied to find CsA concentration in four patients receiving oral CsA regimen which indicates it as a promising method for on-site detection applications.