Fluorescent Hydroxylamine Derived from the Fragmentation of PAMAM Dendrimers for Intracellular Hypochlorite Recognition

Abstract

Herein, a promising sensing approach based on the structure fragmentation of poly(amidoamine) (PAMAM) dendrimers for the selective detection of intracellular hypochlorite (OCl(-)) is reported. PAMAM dendrimers were easily disrupted by a cascade of oxidations in the tertiary amines of the dendritic core to produce an unsaturated hydroxylamine with blue fluorescence. Specially, the novel fluorophore was only sensitive to OCl(-), one of reactive oxygen species (ROS), resulting in an irreversible fluorescence turn-off. The fluorescent hydroxylamine was selectively oxidised by OCl(-) to form a labile oxoammonium cation that underwent further degradation. Without using any troublesomely synthetic steps, the novel sensing platform based on the fragmentation of PAMAM dendrimers, can be applied to detect OCl(-) in macrophage cells. The results suggest that the sensing approach may be useful for the detection of intracellular OCl(-) with minimal interference from biological matrixes.

Strong Fluorescence of Poly(N-vinylpyrrolidone) and Its Oxidized Hydrolyzate

“…It is known that secondary amines can be easily oxidized to produce hydroxylamine or N→O compounds . As the hydrolysis of NMP was carried out in the air atmosphere, so the hydrolyzed product MBA may react with the oxidative O 2 in air to produce hydroxylamine and/or secondary amine oxide (Scheme ).…”

Bioanalytical methods for hypochlorous acid detection: Recent advances and challenges

“…Organic nanoparticles, such as polymers and dendrimers, have also been explored as the nanoprobes for HOCl detection. Poly(amidoamine) (PAMAM) dendrimers for the selective detection of HOCl have been reported by Wu and co-workers [321]. The dendrimers were found to be sensitive towards HOCl as the structure could be disrupted by a cascade of oxidation in the tertiary amines of the dendritic core to produce an unsaturated hydroxylamine.…”

Bifunctional Pyrrolidin-2-one Terminated Manganese Oxide Nanoparticles for Combined Magnetic Resonance and Fluorescence Imaging

“…In nitrogen-containing polymers, N-branched amine groups are believed to be at the core of the fluorophore in the oligomeric species. The fluorescence of nitrogen-containing small molecules (e.g., triethylenetetraamine) was enhanced in the presence of an oxidant such as peroxides. , The oxidation of an amine group, followed by rearrangement and formation of the oxime structural motif, is thought to be one of the pathways that generate photoluminescent functionalities within the molecules . Similarly, formation of hydroxylamine and N→O groups was also postulated to be responsible for the fluorescence of N -methylpyrrolidone and poly­( N -vinylpyrrolidone) .…”

“…54,57 The oxidation of an amine group, followed by rearrangement and formation of the oxime structural motif, is thought to be one of the pathways that generate photoluminescent functionalities within the molecules. 59 Similarly, formation of hydroxylamine and N→O groups was also postulated to be responsible for the fluorescence of N-methylpyrrolidone and poly(N-vinylpyrrolidone). 54 Given that the present NP synthesis involves heating the closely related pyrrolidin-2-one to high temperatures and that MnO, our end-product, is a well-known potent oxidation catalyst, 60 a similar mechanism could be at play here (postulated candidate fluorophores are briefly discussed in the SI).…”