Showing papers by "Nikhil R. Jana published in 2009"

Fluorescent Carbon Nanoparticles: Synthesis, Characterization, and Bioimaging Application

Abstract: Fluorescent carbon nanoparticles (CNPs) 2−6 nm in size with a quantum yield of about ∼3% were synthesized via nitric acid oxidation of carbon soot, and this approach can be used for milligram-scale synthesis of these water-soluble particles. These CNPs are nanocrystalline with a predominantly graphitic structure and show green fluorescence under UV exposure. Nitric acid oxidation induces nitrogen and oxygen incorporation into soot particles, which afforded water solubility and a light-emitting property; the isolation of small particles from a mixture of different sized particles improved the fluorescence quantum yield. These CNPs show encouraging cell-imaging applications. They enter into cells without any further functionalization, and the fluorescence property of these particles can be used for fluorescence-based cell imaging applications.

Functionalized Plasmonic-Fluorescent Nanoparticles for Imaging and Detection

Abstract: Plasmonic-fluorescent composite nanoparticles are considered as unique, multifunctional nanoprobes for plasmon- and fluorescence-based imaging and detection. However, their synthesis is challenging due to fluorescence quenching of the fluorophore by plasmonic particles and most of the successful methods produce composite particles of large size (diameter > 50 nm), which limit their wider applications. Here we report 20-30 nm diameter plasmonic-fluorescent composite nanoparticles with reasonable fluorescence quantum yield (12-16%). These particles are composed of 3-6 nm diameter Au/Ag cores and fluorescein-incorporated polymeric shells. They have high water solubility, good colloidal stability, stable fluorescence properties, and are amenable in deriving various functional nanoprobes. Different functional nanoprobes are derived from these composites and successfully used for fluorescence-based cell labeling as well as plasmon-based detection applications.

Imidazole Based Biocompatible Polymer Coating in Deriving <25 nm Functional Nanoparticle Probe for Cellular Imaging and Detection

Abstract: Although synthetic methods for high quality near-monodispersed nanoparticles of metal and semiconductor are well established, their conversion into various functional nanoparticles is challenging. We report here an imidazole based polymer coating that can be used in deriving <25 nm diameter water-soluble functional nanoparticles. The advantage of this coating method is that it is applicable to various hydrophobic metal and semiconductor nanoparticles, provides different chemical functionality and surface charge to the coated particle, induces minimum cytotoxicity, and can be used in deriving a bifunctional cellular nanoprobe for simultaneous imaging and surface enhanced Raman spectroscopy based detection.

Fluorescent Carbon Nanoparticle: Synthesis, Characterization and Bio-imaging Application

Abstract: Fluorescent carbon nanoparticle (CNP) having 2-6 nm in size with quantum yield of about ~3% were synthesized via nitric acid oxidation of carbon soot and this approach can be used for milligram scale synthesis of these water soluble particles. These CNPs are nano-crystalline with predominantly graphitic structure and shows green fluorescence under UV exposure. While nitric acid oxidation induces nitrogen and oxygen incorporation into soot particle that afforded water solubility and light emitting property; the isolation of small particles from a mixture of different size particles improved the fluorescence quantum yield. These CNP shows encouraging cell imaging application. They enter into cell without any further functionalization and fluorescence property of these particles can be used for fluorescence based cell imaging application.

Transition metal ion doped semiconductor nanocrystals and a process for the preparation thereof

Abstract: The present invention deals with transition metal ions doped semiconductor nanocrystals that are free from heavy metals like cadmium and therefore environment friendly and useful for biological applications. The present invention also describes a process for the preparation of such transition metal ion doped semiconductor nanocrystals, where the reactions take place at a temperature less than 3000C. The said doped nanocrystals are stable in air and under UV radiation in both solution and precipitated solid form.

Nontoxic, water-soluble and functionalized transition metal ion doped semiconductor nanocrystals and a process for the preparation thereof

Abstract: The present invention deals with nontoxic, water soluble and functionalized transition metal ion doped ZnS semiconductor nanocrystals. These nanocrystals are effective in fluorescent biological labeling and can be used as bioconjugates useful for different biomedical applications. The present invention further includes within its scope a process for preparing these functionalized transition metal ion doped semiconductor nanocrystals comprising the steps of polymer coating, polymerization followed by purification and functionalization, providing long shelf life. The present invention also includes a process of fluorescence biological labeling with the nontoxic, water soluble and functionalized transition metal ion doped semiconductor nanocrystals for long term cell imaging applications.