Biomedical subjects

Fabien Pinaud

Publications and source records attributed to Fabien Pinaud.

6 recordsLinked to original sources

PubMed2006

Peptide coated quantum dots for biological applications.

Quantum dots (QDOTs) have been widely recognized by the scientific community and the biotechnology industry, as witnessed by the exponential growth of this field in the past several years. We describe the synthesis and characterization of visible and near infrared QDots--a critical step for engineering organic molecules like proteins and peptides for building nanocomposite materials with multifunctional properties suitable for biological applications.

Coated Materials, Biocompatible↗

PubMed2005

Advances in fluorescence imaging with quantum dot bio-probes.

After much effort in surface chemistry development and optimization by several groups, fluorescent semiconductor nanocrystals probes, also known as quantum dots or qdots, are now entering the realm of biological applications with much to offer to biologists. The road to success has been paved with hurdles but from these efforts has stemmed a multitude of original surface chemistries that scientists in the biological fields can draw from for their specific biological applications. The ability to easily modulate the chemical nature of qdot surfaces by employing one or more of the recently developed qdot coatings, together with their exceptional photophysics have been key elements for qdots to acquire a status of revolutionary fluorescent bio-probes. Indeed, the unique properties of qdots not only give biologists the opportunity to explore advanced imaging techniques such as single molecule or lifetime imaging but also to revisit traditional fluorescence imaging methodologies and extract yet unobserved or inaccessible information in vitro or in vivo.

Chromogenic Compounds↗

PubMed2005

Comparison of photophysical and colloidal properties of biocompatible semiconductor nanocrystals using fluorescence correlation spectroscopy.

A number of different surface chemistries have been developed in recent years to render semiconductor nanocrystals (NCs) stable in water and biocompatible. However, most of these surface modifications affect NCs' photophysical properties, calling for a method to simultaneously monitor colloidal and fluorescence properties. Fluorescence correlation spectroscopy (FCS) combined with ensemble spectroscopic methods and Monte Carlo simulations were used to interpret and derive photophysical as well as colloidal properties of four different NC surface treatments. Using a novel FCS scheme with alternating laser excitation at two different intensities, we first ruled out influences from optical gradient forces (optical trapping). We then compared concentration of emitting particles, brightness per particle, saturation intensity, blinking (intermittency), hydrodynamic radius, and propensity for aggregation of the different bioconjugated NCs. This approach was successfully applied during the development and optimization of peptide-coated NCs.

Biocompatible Materials↗

PubMed2005

Enhancing the photoluminescence of peptide-coated nanocrystals with shell composition and UV irradiation.

The composition and structure of inorganic shells grown over CdSe semiconductor nanocrystal dots and rods were optimized to yield enhanced photoluminescence properties after ligand exchange followed by coating with phytochelatin-related peptides. We show that, in addition to the peptides imparting superior colloidal properties and providing biofunctionality in a single-step reaction, the improved shells and pretreatment with UV irradiation resulted in high quantum yields for the nanocrystals in water. Moreover, peptide coating caused a noticeable red-shift in the absorption and emission spectra for one of the tested shells, suggesting that exciton-molecular orbital (X-MO) coupling might take place in these hybrid inorganic-organic composite materials.

Cadmium Compounds↗

PubMed2004

Bioactivation and cell targeting of semiconductor CdSe/ZnS nanocrystals with phytochelatin-related peptides.

Synthetic phytochelatin-related peptides are used as an organic coat on the surface of colloidal CdSe/ZnS semiconductor nanocrystals synthesized from hydrophobic coordinating trioctyl phosphine oxide (TOPO) solvents. The peptides are designed to bind to the nanocrystals via a C-terminal adhesive domain. This adhesive domain, composed of multiple repeats of cysteines pairs flanked by hydrophobic 3-cyclohexylalanines, is followed by a flexible hydrophilic linker domain to which various bio-affinity tags can be attached. This surface coating chemistry results in small, buffer soluble, monodisperse peptide-coated nanoparticles with high colloidal stability and ensemble photophysical properties similar to those of TOPO-coated nanocrystals. Various peptide coatings are used to modulate the nanocrystal surface properties and to bioactivate the nanoparticles. CdSe/ZnS nanocrystals coated with biotinylated peptides efficiently bind to streptavidin and are specifically targeted to GPI-anchored avidin-CD14 chimeric proteins expressed on the membranes of live HeLa cells. This peptide coating surface chemistry provides a novel approach for the production of biocompatible photoluminescent nanocrystal probes.

Adhesiveness↗

PubMed2003

The power and prospects of fluorescence microscopies and spectroscopies.

Recent years have witnessed a renaissance of fluorescence microscopy techniques and applications, from live-animal multiphoton confocal microscopy to single-molecule fluorescence spectroscopy and imaging in living cells. These achievements have been made possible not so much because of improvements in microscope design, but rather because of development of new detectors, accessible continuous wave and pulsed laser sources, sophisticated multiparameter analysis on one hand, and the development of new probes and labeling chemistries on the other. This review tracks the lineage of ideas and the evolution of thinking that have led to the actual developments, and presents a comprehensive overview of the field, with emphasis put on our laboratory's interest in single-molecule microscopy and spectroscopy.

Equipment Design↗