Inhibition of amyloid fibrillation and clearance of amyloid fibrils/plaques are essential for the prevention and treatment of various neurodegenerative disorders involving protein aggregation. Herein, we report curcumin-functionalized gold nanoparticles (Au-curcumin) of hydrodynamic diameter 10-25 nm, which serve to inhibit amyloid fibrillation and disintegrate/dissolve amyloid fibrils. In nanoparticle form, curcumin is water-soluble and can efficiently interact with amyloid protein/peptide, offering enhanced performance in inhibiting amyloid fibrillation and dissolving amyloid fibrils. Our results imply that nanoparticle-based artificial molecular chaperones may offer a promising therapeutic approach to combat neurodegenerative disease.

Development of unique bioimaging probes offering essential information's about bio environments are an important step forward in biomedical science. Nanotechnology offers variety of novel imaging nanoprobes having high-photo stability as compared to conventional molecular probes which often experience rapid photo bleaching problem. Although great advances have been made on the development of semiconductor nanocrystals-based fluorescent imaging probes, potential toxicity issue by heavy metal component limits their in vivo therapeutic and clinical application. Recent works show that fluorescent gold clusters (FGCs) can be a promising nontoxic alternative of semiconductor nanocrystals. FGCs derived imaging nanoprobes offer stable and tunable visible emission, small hydrodynamic size, high biocompatibility and have been exploited in variety in vitro and in vivo imaging applications. In this review, we will focus on the synthetic advances and bioimaging application potentials of FGCs. In particular, we will emphasize on functional FGCs that are bright and stable enough to be useful as bioimaging probes.

Amyloid protein fibrillation is responsible for variety of neurological disorders and thus inhibition of fibrillation is a potential therapeutic strategy for these diseases.Recent study shows that nanoparticles can significantly influence the kinetics of amyloid fibrillation, depending on their surface chemistry. Here we demonstrate that amyloid fibril formation can be completely inhibited by nanoparticles coated with histidine-based polymer. We have designed nanoparticles with modular surface chemistry and found that the presence of cationic and anionic surface charge, along with weakly hydrophobic functional groups, is essential in inhibiting the amyloid fibrillation processes. This work shows that the appropriate nanoprobe can be designed for controlling the amyloid fibrillation kinetics and for complete inhibition of fibrillation.

Although it is now well recognized that plasmonic gold/silver nanoparticle based aggregates having electromagnetic hot spots are responsible for high sensitivity in surface-enhanced Raman spectroscopy (SERS), the high yield and reproducible production of such nanostructures are challenging and limit their practical application. Here we show a graphene oxide (GO) based approach in generating stable electromagnetic hot spots with high yield from colloidal plasmonic nanoparticles that leads to highly reproducible, stable and sensitive SERS for a wide range of molecules with Raman enhancement factors between 10(8) to 10(11). The liquid crystalline property of dispersed GO directs the Raman probe induced controlled aggregation of plasmonic particles, restricting those aggregates to small and discrete clusters and stabilizing those clusters for longer times-offering the Raman probe induced 'turn on' SERS with high sensitivity and reproducibility. The presented approach is broadly applicable to different types of colloidal plasmonic particles and a wide range of Raman probes and is ideal for SERS based reliable detection of analyte at ultralow concentration.

Doped semiconductor nanocrystals such as Mn doped ZnS, Mn doped ZnSe and Cu doped InZnS, are considered as new classes of fluorescent biological probes with low toxicity. Although the synthesis in high quality of such nanomaterials is now well established, transforming them into functional fluorescent probes remains a challenge. Here we report a fluorescent cellular imaging probe made of high quality doped semiconductor nanocrystals. We have identified two different coating approaches suitable for transforming the as synthesized hydrophobic doped semiconductor nanocrystals into water-soluble functional nanoparticles. Following these approaches we have synthesized TAT-peptide- and folate-functionalized nanoparticles of 10-80 nm hydrodynamic diameter and used them as a fluorescent cell label. The results shows that doped semiconductor nanocrystals can be an attractive alternative for conventional cadmium based quantum dots with low toxicity.