Amyloid protein fibrillation is associated with a variety of neurodegenerative and other diseases, and their efficient detection and monitoring can greatly advance early diagnosis and therapy. Herein, we report a fluorescent "switch-on" probe for the reliable detection and monitoring of amyloid fibrils. The probe consists of a peptide component for binding with amyloid structure and a color component with an aggregation-induced green emission property. This probe is nonfluorescent in the presence of amyloid forming monomer protein/peptide, but fluorescence "switch-on" occurs after binding with amyloid fibrils. Compared to conventionally used thioflavin T, this probe offers a high signal-to-noise ratio, which is unaffected by the quencher ion/nanoparticle. The proposed new probe has been used for the detection and monitoring of amyloid fibrils produced by a wide variety of amyloid protein/peptides and can be extended for in vitro diagnostic applications.

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Quorum sensing (QS) plays an important role in virulence of Pseudomonas aeruginosa, blocking of QS ability are viewed as viable antimicrobial chemotherapy and which may prove to be a safe anti-virulent drug. Bioactive components from Piper betle have been reported to possess antimicrobial ability. This study envisages on the anti-QS properties of ethanolic extract of P. betle leaf (PbLE) using P. aeruginosa PAO1 as a model organism. A marked reduction in swarming, swimming, and twitching ability of the bacteria is demonstrated in presence of PbLE. The biofilm and pyocyanin production also shows a marked reduction in presence of PbLE, though it does not affect the bacterial growth. Thus, the studies hint on the possible effect of the bioactive components of PbLE on reducing the virulent ability of the bacteria; identification of bioactive compounds should be investigated further.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-015-0348-8) contains supplementary material, which is available to authorized users.

Aggregation induced emission (AIE) active molecules are widely used for fluorescence “turn-on” detection applications with the unique advantages over conventional fluorescent probes. Transformation of AIE molecule into functional nanoparticle can greatly expand their biomedical application potential. Here we report an approach for preparation of 20–80 nm size functional nanoparticle made of AIE molecule. The approach involves aggregation of AIE active tetraphenylethene (TPE) molecule in the presence of functional TPE molecule. Following this approach we have synthesized TPE-based nanoparticle functionalized with polyethylene glycol, primary amine, aspartic acid, glucose, and arginine. Compared to reported methods of making AIE-based nanoparticles, presented nanoparticles have distinct advantages that they are composed of AIE molecules only (without any non-AIE molecule/polymer) and wide variety of surface functionalization can be achieved by this approach. Nanoparticles have good colloidal stability with fluorescence quantum yield of 12–15% and fluorescence remains intact in the presence of conventional quenchers. These nanoprobes are used as fluorescent cell labels and can be extended for preparation of AIE molecule-based different nanoprobes.