Energy-Transfer Schemes To Probe Fluorescent Nanocarriers and Their Emissive Cargo

Abstract

A strategy to probe supramolecular nanocarriers and their cargo in the intracellular space was developed on the basis of fluorescence measurements and energy transfer. It relies on the covalent attachment of an energy donor, or acceptor, to the macromolecular backbone of amphiphilic polymers and the noncovalent encapsulation of a complementary acceptor, or donor, in the resulting micelles. In aqueous environments, these macromolecules self-assemble into nanostructured constructs and bring the complementary chromophores in close proximity to enable efficient energy transfer. These supramolecular assemblies travel from the extracellular to the intracellular space and retain their integrity in the process. Indeed, donors and acceptors remain close to each other after internalization, and excitation of the former chromophores translates into significant intracellular emission from the latter. Furthermore, these supramolecular assemblies exchange their components with fast kinetics in aqueous dispersions because of the reversible character of the noncovalent contacts holding them together. As a result, micelles incorporating exclusively the donors and nanocarriers containing only the acceptors scramble their chromophoric building blocks, upon mixing, to allow the transfer of energy. These dynamic processes can be reproduced in the intracellular environment with the sequential incubation of cells with the two sets of complementary nanostructured assemblies. Thus, these operating principles and choice of supramolecular synthons are particularly valuable to monitor self-assembling nanocarriers and their cargo inside living cells and can facilitate the elucidation of the behavior of these promising delivery vehicles in a diversity of biological specimens.

Dual‐Mode, Anisotropy‐Encoded, Ratiometric Fluorescent Nanosensors: Towards Multiplexed Detection

“…In particular, the intensity of the C band is 50 % weaker than that observed for C 0.5 under the same experimental conditions (Figure , red dashed line). Such a decrease is consistent with the occurrence of a FRET process (with an efficiency η FRET =0.5), from the core to the F molecules onto the NP surfaces (Scheme c) . This interpretation is supported by the very good match between the experimental spectrum and the one calculated in the case of sensitization of F emission, (in case of η FRET =0.5, Figure , dashed green line), ruling out other quenching mechanisms.…”

Förster Resonance Energy Transfer across interpolymer complexes of poly(acrylic acid) and poly(acrylamide)

“…The complexation is driven either by van der Waals forces to form stereocomplexes 8 , polyelectrolyte bindings between polyacids 9 , coordination complexes 10 or hydrogen bonding [11][12] . All of these have been investigated over recent years and careful polymer design can lead to new composite materials 8,13 and new applications as sensors [14][15] or delivery vehicles 11,16 . There are a variety of methods for detecting interpolymer complexes (IPC) including viscometry, conductivity measurements, NMR spectroscopy and fluorescence 9,[17][18][19] .…”

“…Polymers containing a single chromophore do not undergo FRET processes but other factors can affect their decay, therefore these need to be studied to give suitable reference states. Attachment of chromophores onto small conjugating oligomeric systems has been carried out before 16,36,44 . These studies typically used low molecular weight oligomers or polymers with fluorescent chain ends to tag the end of intercalating dyes 44 .…”

Bioimaging with Macromolecular Probes Incorporating Multiple BODIPY Fluorophores

“…Compounds 3–5 , 10 , 12 , and 14 were prepared according to literature procedures. 29,36–38 The synthesis of 6 and 8 are illustrated in Figures S1 and S2. GPC was performed with a Phenomenex Phenogel 5-µm MXM column (7.8 × 300 mm) operated with a Shimadzu Nexera X2 system in THF at a flow rate of 1.0 mL min −1 .…”