Centrifugation aided highly sensitive detection of nitrite with a dye–silica conjugate featuring cleavable linkages

Rhodamine–silica nanocomposite bridged by a cleavable linker was used for highly sensitive nitrite detection via analyte triggered release of rhodamine from silica particles. Centrifugal removal of pristine nanoconjugate from the assay medium effectively decreased background signals in the supernatant whereas rhodamine unleashed from silica platform is retained in the supernatant, enabling facile detection of nitrite with an assay limit of 50 nM which is 400 folds lower than legislated maximum contaminant levels of nitrite in drinking water. Assays based on small molecular chemosensors are often compromised by their intrinsic fluorescence signals and low aqueous compatibility. The performance of water compatible rhodamine–silica nanocomposite suggests broad analytical potentials of centrifugal nanoparticulate systems with dyes conjugated via appropriate cleavable linkers.