4 research outputs found
Facile and Rapid Access to Glyconanocapsules by CuAAC Interfacial Polyaddition in Miniemulsion Conditions
Glyconanocapsules with a biocompatible oily core have
been successfully
prepared by copperÂ(I)-catalyzed azideâalkyne cycloaddition
(CuAAC) interfacial step growth polymerization between 6,6âČ-diazido-6,6âČ-dideoxysucrose
and bisÂ(propargyloxy)Âbutane in oil-in-water miniemulsion conditions.
Optimization of the interfacial polymerization process in dispersed
medium afforded the rapid and reproducible preparation of stable monodispersed
glyconanocapsules having a diameter around 200 nm
Red Emitting Neutral Fluorescent Glycoconjugates for Membrane Optical Imaging
A family of neutral fluorescent probes
was developed, mimicking
the overall structure of natural glycolipids in order to optimize
their membrane affinity. Nonreducing commercially available di- or
trisaccharidic structures were connected to a pushâpull chromophore
based on dicyanoisophorone electron-accepting group, which proved
to fluoresce in the red region with a very large Stokes shift. This
straightforward synthetic strategy brought structural variations to
a series of probes, which were studied for their optical, biophysical,
and biological properties. The insertion properties of the different
probes into membranes were evaluated on a model system using the Langmuir
monolayer balance technique. Confocal fluorescence microscopy performed
on muscle cells showed completely different localizations and loading
efficiencies depending on the structure of the probes. When compared
to the commercially available ANEPPS, a family of commonly used membrane
imaging dyes, the most efficient probes showed a similar brightness,
but a sharper pattern was observed. According to this study, compounds
bearing one chromophore, a limited size of the carbohydrate moiety,
and an overall rod-like shape gave the best results
Optical Properties of a Visible PushâPull Chromophore Covalently Bound to Carbohydrates: Solution and Gas-Phase Spectroscopy Combined to Theoretical Investigations
The use of visible absorbing and fluorescent tags for sensing and structural analysis of carbohydrates is a promising route in a variety of medical, diagnostic, and therapeutic contexts. Here we report an easy method for covalent attachment of nonfluorescent pushâpull chromophores based on the 4-cyano-5-dicyanomethylene-2-oxo-3-pyrroline ring to carbohydrate moieties. The impact of sugar grafting on the optical properties of the pushâpull chromophore in the gas phase and in solution was investigated by absorption and action spectroscopy and theoretical methods. The labeled sugars efficiently absorb photons in the visible range, as demonstrated by their intense photodissociation in a quadrupole ion trap. A strong blue shift (â70 nm) of the gas-phase photodissociation intensity maximum is observed upon sugar grafting, whereas no such effect is visible on the solution absorption spectra. Molecular dynamics simulations of labeled maltose in the gas phase describe strong interactions between the sulfonated chromophore and the carbohydrate, which lead to cyclic conformations. These are not observed in the simulations with explicit solvation. Time-dependent density functional theory (TD-DFT) calculations on model molecules permit us to attribute the observed shift to the formation of such cyclic conformations and to the displacement of the negative charge relative to the aromatic moiety of the chromophore
General and Scalable Approach to Bright, Stable, and Functional AIE Fluorogen Colloidal Nanocrystals for in Vivo Imaging
Fluorescent
nanoparticles built from aggregation-induced emission-active organic
molecules (AIE-FONs) have emerged as powerful tools in life science
research for in vivo bioimaging of organs, biosensing, and therapy.
However, the practical use of such biotracers has been hindered owing
to the difficulty of designing bright nanoparticles with controlled
dimensions (typically below 200 nm), narrow size dispersity and long
shelf stability. In this article, we present a very simple yet effective
approach to produce monodisperse sub-200 nm AIE fluorescent organic
solid dispersions with excellent redispersibility and colloidal stability
in aqueous medium by combination of nanoprecipitation and freeze-drying
procedures. By selecting polymer additives that simultaneously act
as stabilizers, promoters of amorphousâcrystalline transition,
and functionalization/cross-linking platforms, we demonstrate a straightforward
access to stable nanocrystalline FONs that exhibit significantly higher
brightness than their amorphous precursors and constitute efficient
probes for in vivo imaging of the normal and tumor vasculature.
FONs design principles reported here are universal, applicable to
a range of fluorophores with different chemical structures and crystallization
abilities, and are suitable for high-throughput production and manufacturing
of functional imaging probes