Dual functional amphiphilic sugar-coated AIE-active fluorescent organic nanoparticles for the monitoring and inhibition of insulin amyloid fibrillation based on carbohydrate-protein interactions.

Amyloid-related diseases, such as Alzheimer's disease, are all considered to be related to the deposition of amyloid fibrils in the body. Insulin is a protein hormone that easily undergoes aggregation and fibrillation to form more toxic amyloid-like fibrils. So far, it is still challenging to develop a new protocol to study the ex situ detection and in situ inhibition of amyloid fibrillation. Here, we reported a modular synthetic strategy to construct nine amphiphilic sugar-coated AIE-active fluorescent organic nanoparticles (FONs, TPE2/3/4X, X = G, M or S) with glucosamine (G), mannose (M) or sialic acid (S) as a hydrophilic moiety and tetraphenylethylene (TPE) as a hydrophobic AIE core. The carbohydrate-protein interactions between insulin and TPE2/3/4X were investigated by fluorescence spectroscopy, circular dichroism spectroscopy and transmission electron microscopy. Among the nine FON AIEgens, TPE2G was screened out as the best dual functional FON for the ex situ detection and in situ inhibition of the insulin fibrillation process, indicating that the glycosyl moiety exhibited a crucial effect on the detection/inhibition of insulin fibrillation. The molecular dynamics simulation results showed that the binding mechanism between TPE2G and native insulin was through weak interactions dominated by van der Waals interactions and supplemented by hydrogen bonding interactions to stabilize an α-helix of the insulin A chain, thereby inhibiting the insulin fibrillation process. This work provides a powerful protocol for the further research of amyloid-related diseases based on carbohydrate-protein interactions.

Water-soluble AIE-active Fluorescent Organic Nanoparticles: Design, Preparation and Application for Specific Detection of Cyanide in Water and Food Samples.

A dilactosyl-dicyanovinyl-functionalized tetraphenylethene (TPELC) was designed, synthesized and used for ratiometric sensing of cyanide. TPELC was comprised of three moieties (tetraphenylethylene, dicyanovinyl group and lactose unit) in one molecule, making TPELC water-soluble and aggregation-induced emission (AIE)-active and selectively reactive to cyanide. Compared with other reported fluorescent probes containing dicyanovinyl group, TPELC is the first AIE luminogen to be assembled as fluorescent organic nanoparticles (FONs) for sensing of cyanide in water without the use of surfactant or the help of organic solvents based on the nucleophilic addition reaction. The detection mechanism was verified by liquid chromatograph mass spectrometry experiments and by protonation of cyanide to reduce the nucleophilicity of cyanide. In addition, TPELC was used for detection of the cyanide content of food samples and test strips were developed to simplify the detection procedure.