Revealing the structure and functionality of graphene oxide and reduced graphene oxide/pyrene carboxylic acid interfaces by correlative spectral and imaging analysis.

A high-end correlated spectral and imaging multianalysis, adapted for bidimensional systems, is presented here to analyze graphene oxide (GO) and reduced GO (rGO) modified with pyrene carboxylic acid (PCA). Confocal Raman mapping was used next to two-photon excited Fluorescence Lifetime Imaging Microscopy (FLIM) to characterize the distribution of PCA on GO and rGO and compared to UV-vis and X-ray Photoelectron Spectroscopy (XPS) analysis of the materials. Raman imaging clearly highlights the difference in the spatial distribution of PCA molecules on GO and rGO. Two-photon excited FLIM helped in gaining insight into the elusive phenomena and effects occurring at the GO-PCA interface level. Apart from the charge transfer effects from PCA molecules to GO, the GO structure depends on the molecular orientation and the spatial distribution of PCA molecules identified by different sp2 network domains in Raman mapping. Heating of GO-PCA results in an enhancement of the sp2 network presumably as the PCA aromatic core becomes fused into the GO nanosheets whilst enriching the resulting rGO nanosheets with carboxyl functionalities. This "healing" effect observed in rGO-PCA might be of high importance for applications using rGO-PCA matrices and interfaces in particular for electrical devices.

IR780-dye loaded gold nanoparticles as new near infrared activatable nanotheranostic agents for simultaneous photodynamic and photothermal therapy and intracellular tracking by surface enhanced resonant Raman scattering imaging.

Due to the good transparency of the human tissue in the biological spectral window, near-infrared (NIR)-dye loaded nanosystems enable more effective light-activated therapy and better contrast imaging with major impact on nanomedicine. Herein, we prepare Pluronic coated gold nanoparticles incorporating the hydrophobic NIR dye, IR780 iodide (GNP-Plu-IR780) to provide water-solubility and stability and demonstrate the proficiency of combining photodynamic and photothermal therapeutic activity with surface-enhanced resonance Raman scattering (SERRS) imaging facility. The potential of GNP-Plu-IR780 to operate as NIR-activatable agents was first assessed in aqueous solution by singlet oxygen generation measurements and monitoring the temperature increase of the nanoparticles. Subsequent in vitro uptake studies by dark field and differential interference contrast (DIC) microscopy reveal massive internalization of GNP-Plu-IR780 by murine colon carcinoma cells (C-26). Moreover, by exploiting the SERRS effect under 785 nm laser excitation we were able to perform intracellular tracking of GNP-Plu-IR780. Finally, NIR irradiation experiments conducted in vitro against C-26 cells show efficient phototherapeutic activity induced by GNP-Plu-IR780 with no dark cytotoxicity. Moreover, when compared to the administration of free drug or non-loaded GNP-Plu, the higher phototherapeutic activity of GNP-Plu-IR780 indicates the occurrence of cooperative synergistic effects by simultaneous photodynamic and photothermal activity.

Flexible and Tunable 3D Gold Nanocups Platform as Plasmonic Biosensor for Specific Dual LSPR-SERS Immuno-Detection.

Early medical diagnostic in nanomedicine requires the implementation of innovative nanosensors with highly sensitive, selective, and reliable biomarker detection abilities. In this paper, a dual Localized Surface Plasmon Resonance - Surface Enhanced Raman Scattering (LSPR- SERS) immunosensor based on a flexible three-dimensional (3D) gold (Au) nanocups platform has been implemented for the first time to operate as a relevant "proof-of-concept" for the specific detection of antigen-antibody binding events, using the human IgG - anti-human IgG recognition interaction as a model. Specifically, polydimethylsilane (PDMS) elastomer mold coated with a thin Au film employed for pattern replication of hexagonally close-packed monolayer of polystyrene nanospheres configuration has been employed as plasmonic nanoplatform to convey both SERS and LSPR readout signals, exhibiting both well-defined LSPR response and enhanced 3D electromagnetic field. Synergistic LSPR and SERS sensing use the same reproducible and large-area plasmonic nanoplatform providing complimentary information not only on the presence of anti-human IgG (by LSPR) but also to identify its specific molecular signature by SERS. The development of such smart flexible healthcare nanosensor platforms holds promise for mass production, opening thereby the doors for the next generation of portable point-of-care devices.