Fluorescent layered double hydroxide nanoparticles for biological studies

Layered double hydroxide (LDH) nanoparticles have the potential to benefit a myriad of medical, consumer and industrial products if intricate control of the nanoscale architecture and understanding of the biological interactions and potential toxicity of the LDH nanomaterials are achieved. Here, we report the synthesis and fractionation of LDH nanomaterials of well defined spatial characteristics through the careful control of synthesis conditions and the use of ultracentrifugation. The appropriateness of a range of fluorescent dyes, for labelling LDH nanoparticles to enable biological tracking, has also been investigated. These dyes include fluorescein, fluorescein isothiocyanate (FITC), 8-aminonaphthelene-1,3,6-trisulfonic acid (ANTS) and 8-aminopyrene-1,3,6-trisulfonic acid (APTS). Thermal degradation of the popular FITC dye during nanoparticle synthesis was revealed and suitable alternative fluorescent molecules established. Furthermore, we report for the first time the application of size exclusion chromatography on LDH nanoparticles as a fast, reliable and efficient method to achieve purification without causing nanoparticle agglomeration.