Fluorescent Polymer-AS1411-Aptamer Probe for dSTORM Super-Resolution Imaging of Endogenous Nucleolin.

Nucleolin is a multifunctional protein involved in essential biological processes. To precisely localize it and unravel its different roles in cells, fluorescence imaging is a powerful tool, especially super-resolution techniques. Here, we developed polymer-aptamer probes, both small and bright, adapted to direct stochastic optical reconstruction microscopy (dSTORM). Well-defined fluorescent polymer chains bearing fluorophores (AlexaFluor647) and a reactive end group were prepared via RAFT polymerization. The reactive end-group was then used for the oriented conjugation with AS1411, a DNA aptamer that recognizes nucleolin with high affinity. Conjugation via strain-promoted alkyne/azide click chemistry (SPAAC) between dibenzylcyclooctyne-ended fluorescent polymer chains and 3'-azido-functionalized nucleic acids proved to be the most efficient approach. In vitro and in cellulo evaluations demonstrated that selective recognition for nucleolin was retained. Their brightness and small size make these polymer-aptamer probes an appealing alternative to immunofluorescence, especially for super-resolution (10-20 nm) nanoscopy. dSTORM imaging demonstrated the ability of our fluorescent polymer-aptamer probe to provide selective and super-resolved detection of cell surface nucleolin.

Fructose/glycerol/water as a biosourced LTTM solvent to design a variety of sodium alginate-based soft materials with enhanced rheological properties.

Sodium alginate was associated to a ternary solvent composed of fructose, glycerol, and water in a 1:1:5 M ratio (FGW), classified as a natural Low Transition Temperature Mixture (LTTM), to generate various soft materials. The rheological properties of mixtures composed of sodium alginate and FGW were thoroughly analyzed and compared to their aqueous analogues. FGW-based solutions present a pronounced shear-thinning character combined to high viscosity, up to 8000 Pa.s. The overlap concentrations and intrinsic viscosities values evidence a good solvent character of FGW for alginate polymer chains. The increase of alginate concentration in FGW leads to materials with enhanced elasticity (up to 6000 Pa) and high energy of activation (55 kJ/mol). Interestingly, the addition of divalent calcium cations in FGW according to two optimized experimental protocols, allows for the generation of never described ionotropic gels in FGW under various shapes as bulk gels or beads of gels able to encapsulate extracted vegetal actives that are used in the cosmetic industry. Thus, FGW appears as a well-suited solvent of alginate to design a broad range of new biobased soft materials.

Design of a water-soluble chitosan-based polymer with antioxidant and chelating properties for labile iron extraction.

Loosely bound iron, due to its contribution to oxidative stress and inflammation, has become an important therapeutic target for many diseases. A water-soluble chitosan-based polymer exhibiting both antioxidant and chelating properties due to the dual functionalization with DOTAGA and DFO has been developed to extract this iron therefore preventing its catalytic production of reactive oxygen species. This functionalized chitosan was shown to have stronger antioxidant properties compared to conventional chitosan, improved iron chelating properties compared to the clinical therapy, deferiprone, and provided promising results for its application and improved metal extraction within a conventional 4 h hemodialysis session with bovine plasma.