Visual and spectrophotometric determination of cadaverine based on the use of gold nanoparticles capped with cucurbiturils or cyclodextrins

Gold nanoparticles (AuNPs) were capped with cucurbit [6, 7]urils or α- and β-cyclodextrins. The resulting macrocycle-coated AuNPs are shown to enable the visual and spectrophotometric determination of cadaverine. The morphology of the modified AuNPs was characterized by transmission electron microscopy (TEM), which revealed the formation of spherical nanosystems with a narrow size distribution. The macrocycle-coated AuNPs are stable under storage conditions for at least 3 months and well dispersible in water. The cadaverine assay is based on the ability of cucurbiturils and cyclodextrins to recognize diamines. This leads to changes in the UV-vis absorption spectra due to particle aggregation, accompanied by a colour change from red to blue. By using the α-cyclodextrin-coated AuNPs, cadaverine can be quantified by spectrophotometry with a 3.9 μM detection limit.