Eu‐doped ZnAl‐LDH as a Fluorescent Labeling Carrier for the Delivery and Controlled Release of Camptothecin

Abstract

Europium doped Zinc‐aluminum layered double hydroxide (Eu‐doped ZnAl‐LDH) as a fluorescent labeling carrier for the delivery and controlled release of camptothecin (CPT) has been studied. X‐ray diffraction (XRD) patterns showed that the basal spacing of the Eu‐doped ZnAl‐LDH intercalated with CPT (2.27 nm) was larger than that of the initial Eu‐doped ZnAl‐LDH (0.88 nm), indicating the successful intercalation of CPT into the Eu‐doped ZnAl‐LDH carrier. X‐ray photoelectron spectroscopy (XPS) suggested that some Eu(III) were reduced to Eu(II) after the intercalation of CPT into the Eu‐doped ZnAl‐LDH. The release of the CPT from drug carrier was carried out in a simulated medium. It was found that the cumulative concentration of the released CPT was exponential with releasing time, and well conformed to the exponential equation: C=A‐Bexp(‐kt). It took 720 minutes (min) for the complete release of CPT from drug carrier. Fluorescent analyses revealed that the fluorescence attributed to the drug delivery system changed from red, blue‐green, to blue emission during delivery and release of CPT, which may be a favorable signal for “detecting” the delivery and release of CPT. Thus, the present Eu‐doped ZnAl‐LDH may be a feasible drug carrier with fluorescent labeling function.