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Biomedical subjects

Marcel P Bruchez

Publications and source records attributed to Marcel P Bruchez.

7 recordsLinked to original sources
PubMed2006

Quantum dot semiconductor nanocrystals for immunophenotyping by polychromatic flow cytometry.

Immune responses arise from a wide variety of cells expressing unique combinations of multiple cell-surface proteins. Detailed characterization is hampered, however, by limitations in available probes and instrumentation. Here, we use the unique spectral properties of semiconductor nanocrystals (quantum dots) to extend the capabilities of polychromatic flow cytometry to resolve 17 fluorescence emissions. We show the need for this power by analyzing, in detail, the phenotype of multiple antigen-specific T-cell populations, revealing variations within complex phenotypic patterns that would otherwise remain obscure. For example, T cells specific for distinct epitopes from one pathogen, and even those specific for the same epitope, can have markedly different phenotypes. The technology we describe, encompassing the detection of eight quantum dots in conjunction with conventional fluorophores, should expand the horizons of flow cytometry, as well as our ability to characterize the intricacies of both adaptive and innate cellular immune responses.

CD3 Complex↗
PubMed2005

Turning all the lights on: quantum dots in cellular assays.

Quantum dot materials are increasingly used in cellular assays, and offer a powerful and enabling complement to existing methods of labeling proteins, such as green fluorescent protein. These materials give researchers the ability to study specificity and functional responses in cellular systems, in a highly multiplexed manner, at either a molecular or cellular level. The recent literature bears witness to the increasing use of quantum dots for the investigation of chemicals on biological systems, and paves the way to the use of these assays for high-throughput analysis of functional responses in relevant models at scales including molecular, cellular and whole animal.

Cells↗
PubMed2004

Optical coding of mammalian cells using semiconductor quantum dots.

Cell-based assays are widely used to screen compounds and study complex phenotypes. Few methods exist, however, for multiplexing cellular assays or labeling individual cells in a mixed cell population. We developed a generic encoding method for cells that is based on peptide-mediated delivery of quantum dots (QDs) into live cells. The QDs are nontoxic and photostable and can be imaged using conventional fluorescence microscopy or flow cytometry systems. We created unique fluorescent codes for a variety of mammalian cell types and show that our encoding method has the potential to create > 100 codes. We demonstrate that QD cell codes are compatible with most types of compound screening assays including immunostaining, competition binding, reporter gene, receptor internalization, and intracellular calcium release. A multiplexed calcium assay for G-protein-coupled receptors using QDs is demonstrated. The ability to spectrally encode individual cells with unique fluorescent barcodes should open new opportunities in multiplexed assay development and greatly facilitate the study of cell/cell interactions and other complex phenotypes in mixed cell populations.

Animals↗
PubMed2003

Water-soluble quantum dots for multiphoton fluorescence imaging in vivo.

The use of semiconductor nanocrystals (quantum dots) as fluorescent labels for multiphoton microscopy enables multicolor imaging in demanding biological environments such as living tissue. We characterized water-soluble cadmium selenide-zinc sulfide quantum dots for multiphoton imaging in live animals. These fluorescent probes have two-photon action cross sections as high as 47,000 Goeppert-Mayer units, by far the largest of any label used in multiphoton microscopy. We visualized quantum dots dynamically through the skin of living mice, in capillaries hundreds of micrometers deep. We found no evidence of blinking (fluorescence intermittency) in solution on nanosecond to millisecond time scales.

Adipose Tissue↗
PubMed2002

Immunofluorescent labeling of cancer marker Her2 and other cellular targets with semiconductor quantum dots.

Semiconductor quantum dots (QDs) are among the most promising emerging fluorescent labels for cellular imaging. However, it is unclear whether QDs, which are nanoparticles rather than small molecules, can specifically and effectively label molecular targets at a subcellular level. Here we have used QDs linked to immunoglobulin G (IgG) and streptavidin to label the breast cancer marker Her2 on the surface of fixed and live cancer cells, to stain actin and microtubule fibers in the cytoplasm, and to detect nuclear antigens inside the nucleus. All labeling signals are specific for the intended targets and are brighter and considerably more photostable than comparable organic dyes. Using QDs with different emission spectra conjugated to IgG and streptavidin, we simultaneously detected two cellular targets with one excitation wavelength. The results indicate that QD-based probes can be very effective in cellular imaging and offer substantial advantages over organic dyes in multiplex target detection.

3T3 Cells↗
PubMedDate not supplied

Noninvasive imaging of quantum dots in mice.

Quantum dots having four different surface coatings were tested for use in in vivo imaging. Localization was successfully monitored by fluorescence imaging of living animals, by necropsy, by frozen tissue sections for optical microscopy, and by electron microscopy, on scales ranging from centimeters to nanometers, using only quantum dots for detection. Circulating half-lives were found to be less than 12 min for amphiphilic poly(acrylic acid), short-chain (750 Da) methoxy-PEG or long-chain (3400 Da) carboxy-PEG quantum dots, but approximately 70 min for long-chain (5000 Da) methoxy-PEG quantum dots. Surface coatings also determined the in vivo localization of the quantum dots. Long-term experiments demonstrated that these quantum dots remain fluorescent after at least four months in vivo.

Animals↗