New triazine bridged triads based on BODIPY-porphyrin systems: extended absorption, efficient energy transfer and upconverted emission

Two novel triads connecting a BODIPY to ethylenediamine substituted porphyrins via triazine linker have been synthesized and characterized. One of the triads is a linear D-A structure with one BODIPY (D) and one porphyrin (A) bridged by the triazine linker and the other one is a branched A-D4 structure with the porphyrin core linked to four BODIPY units. The triads show extended absorption in the visible region with contributions from both porphyrin (Soret band centred at 410–430 nm) and BODIPY units (strong absorption at ≈ 502 nm) in good agreement with the expected molar ratio. Both triads exhibit linear and nonlinear optical properties featuring an efficient energy transfer from the BODIPY donor to the porphyrin acceptor. The nonlinear upconverted emission properties of the triads were studied by two-photon excitation in the Near-infrared (NIR, 710–930 nm). The maximum two-photon absorption cross-section values for the triads (40–70 GM) are larger than those typically reported in this wavelength range for porphyrins and BODIPY. Both the green emission of BODIPY (≈514 nm) and the red emission of porphyrins (650–750 nm) were observed under NIR excitation at 930 nm. The distinct features of triads, namely i) an extended absorption; ii) an efficient energy transfer and iii) the nonlinear upconverted emission featuring a large separation between the excitation and emission wavelengths could be beneficial for application in sensing and imaging procedures.publishe

Biocompatible hybrids based on nanographene oxide covalently linked to glycolporphyrins: synthesis, characterization and biological evaluation

The major limitation in the development of hybrids based on graphene oxide (GO) and porphyrins is their dispersibility and stability in aqueous systems due to the hydrophobic character induced by porphyrins. Most of the previous approaches reported the direct functionalization of GO with polyethylene glycol (PEG) chains followed by the self-assembly of porphyrins by π-π interactions. Here, new hybrids were prepared using porphyrins previously functionalized with different number/types of glycol branches to be covalently attached through esterification to the carboxyl groups of GO sheets of nanometric dimensions. The number of the glycol chains and its relative position in the porphyrin core showed to be fundamental to improve the hybrids dispersion and stability in aqueous solutions. The best performing hybrids were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, UV-Vis absorption and fluorescence spectroscopy. The in vitro biocompatibility assessment of these hybrids was conducted using human Saos-2 cells. Their effects on cell proliferation and viability, the generation of reactive oxygen species as well as the cell morphology after cell uptake were analysed. The results demonstrate the biocompatibility of these hybrid nanomaterials with human Saos-2 cells, which is very promising for future application in biomedicine namely in cancer therapy.publishe

Dye-labelled polymer chains at specific sites: Synthesis by living/controlled polymerization

International audienceDye-labelled polymer chains are extremely useful in many fields, such as optical imaging, signal amplification in biological diagnostics, light-harvesting and photochromic materials as well as in fluorescence studies about intra- and inter-molecular polymer chain associations, conformations and dynamics of polymer chains. However, in many cases, it is particularly useful that the dye is localized at a specific site, such as the chain-end or the junction between blocks. With the development of living/controlled polymerization techniques, end- and junction-functionalized polymers can be prepared with controlled molecular weights from a huge variety of monomers. This review highlights the state of the art in the strategies leading to one and only one precisely localized dye per polymer chain. Such dye can be introduced at three different steps of the polymerization: i) at the very beginning via the initiator or a chain transfer agent, ii) during polymerization via a functional monomer or a quencher, or iii) after polymerization via covalent binding of a dye-derivative

Novel Malachite Green- and Rhodamine B-labeled cationic chain transfer agents for RAFT polymerization

International audienceTwo novel cationic RAFT agents have been synthesized, one labeled with a Malachite Green (MG) dye and another with a Rhodamine B (RhoB) dye. MG-labeled dithiobenzoate (MGEDBA) was prepared in a straightforward manner after synthesis of MG-ethylammonium chloride that reacted with a precursor dithiobenzoate bearing an activated ester function. However, the analogous reaction with RhoB amino derivative led to a mixture of dithiobenzoate and thioamide derivatives. An alternative approach yielded the RhoB-labeled RAFT agent (RhoBEDBA) with complete conversion. The purification of these dye-labeled RAFT agents was very challenging because of their dual nature (aromatic and ionic). Both MGEDBA and RhoBEDBA were efficient RAFT chain transfer agents to control the polymerization of N,N-dimethylacrylamide (DMA). The resulting α-end-labeled MG- and RhoB-PDMA samples presented low dispersities (Đ<1.2) and both chain-ends were preserved. Finally, we showed that the attachment of RhoB and MG to the PDMA polymer chain-end did not influence the photophysical properties of these dyes. Therefore, these new dye-labeled RAFT agents can be used to prepare various labeled polymers and especially water-soluble ones, to study their conformation and dynamics in solution or at interfaces using fluorescence methods, or as labeled probes for imaging and/or diagnosis purposes

Biotin-end-functionalized highly fluorescent water-soluble polymers

International audienceMany biosensing and imaging systems use fluorescence detection. We present the synthesis of biotin-end-functionalized highly fluorescent water-soluble polymers for potential use in biotin-avidin systems. Statistical polymers of N-acryloylmorpholine (NAM) and N-acryloxysuccinimide (NAS) were prepared by RAFT polymerization using a biotinylated chain transfer agent that ensured 95% end-functionalization of the chains. They were further labeled with a lucifer yellow (LY) dye, yielding 7 to 62 LY fluorophores per polymer chain. The resulting polymers exhibited reduced fluorescence self-quenching, with 7- to 43-fold higher brightness than free LY dye. In addition, they featured low pH sensitivity and very good photobleaching resistance. Moreover, we showed that a more extended polymer conformation was beneficial to the binding of the terminal biotin with streptavidin. This work paves the way for the development of polymers for signal amplification in biosensing assays, labeling of biotin-receptors at cell surfaces in some cancer studies, labeling of antibodies and microscopy imaging purposes

New fluorescent probes based on gallium(III) corrole complexes for the recognition of hydrogen sulfide: a journey from solution to intracellular site

In this work, three fluorescent probes for detection of hydrogen sulfide (H2S) where prepared based on gallium (III) corrole complexes bearing nitro groups at beta-pyrrolic positions. Two of the compounds selected, the 3-nitro5,10,15- tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-NO2) and the 3,17-dinitro-5,10,15-tris (pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-2NO2) present one and two nitro groups directly linked to the beta-pyrrolic position. The third compound, the (E)-3-(2-nitroprop-1-en-1-yl)-5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-EtNO2), has a carbon-carbon double bond spacer between the corrole unit and the nitro group. All these derivatives were obtained from 5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa). The precursor CGa and the derivative CGa-EtNO2 behaved as turn-OFF probes, while compound CGa-NO2 responded as a turn-ON probe in the presence of H2S in the pH range of 5-9. Mechanistic studies show that the interaction of H2S with the probes involves its coordination with gallium(III) and in some cases the reduction of the nitro group to a new aminated corrole. While the formation of the coordination complex with H2S is almost immediate, the kinetics of the reduction is slow. Interestingly, for CGaNO2 the two processes can be explored in a ratiometric sensing of H2S in a non-aqueous solution showing a good linearity over an extended concentration range (5-200 mu M). The response of the corroles to H2S in intracellular medium was studied in 2D cultured cells (HeLa).LISBOA-01-0145-FEDER-029319; LA/P/0056/2020info:eu-repo/semantics/publishedVersio