Investigation of Photophysical and Electrofluorochromic Properties of Gold Nanoparticles Functionalized by a Luminescent Electroactive Complex

Gold nanoparticles (6 nm diameter) functionalized by a luminescent electroactive iridium complex have been synthesized, leading to stable colloidal suspensions in <i>o</i>-dichlorobenzene, a high boiling point solvent. The photophysical properties of these functionalized nanoparticles have been investigated showing a partial quenching of iridium emission by the gold core. Fluorescence correlation spectroscopy has been used to demonstrate that all the iridium complex is actually located on the nanoparticle surface, allowing the investigation of the electrofluorochromic behavior to be investigated for the first time in colloidal plasmonic systems. Compared with the free complex in solution, which shows a well-defined reversible electrochemically monitored luminescence (electrofluorochromism), the iridium-functionalized nanoparticles display a much less pronounced and less potential-dependent electrofluorochomic behavior, unless the potential is pushed toward values where gold stripping occurs

Mixed Copolymer Adlayers Allowing Reversible Thermal Control of Single Cell Aspect Ratio

Dynamic guidance of living cells is achieved by fine-tuning and spatiotemporal modulation on artificial polymer layers enabling reversible peptide display. Adjustment of surface composition and interactions is obtained by coadsorption of mixed poly­(lysine) derivatives, grafted with either repellent PEG, RGD adhesion peptides, or <i>T</i>-responsive poly­(<i>N</i>-isopropylacrylamide) strands. Deposition of mixed adlayers provides a straightforward mean to optimize complex substrates, which is here implemented to achieve (1) thermal control of ligand accessibility and (2) adjustment of relative adhesiveness between adjacent micropatterns, while preserving cell attachment during thermal cycles. The reversible polarization of HeLa cells along orthogonal stripes mimics guidance along natural matrices

Mixed Copolymer Adlayers Allowing Reversible Thermal Control of Single Cell Aspect Ratio

Dynamic guidance of living cells is achieved by fine-tuning and spatiotemporal modulation on artificial polymer layers enabling reversible peptide display. Adjustment of surface composition and interactions is obtained by coadsorption of mixed poly­(lysine) derivatives, grafted with either repellent PEG, RGD adhesion peptides, or <i>T</i>-responsive poly­(<i>N</i>-isopropylacrylamide) strands. Deposition of mixed adlayers provides a straightforward mean to optimize complex substrates, which is here implemented to achieve (1) thermal control of ligand accessibility and (2) adjustment of relative adhesiveness between adjacent micropatterns, while preserving cell attachment during thermal cycles. The reversible polarization of HeLa cells along orthogonal stripes mimics guidance along natural matrices