Advanced microscopies for studying carbonbased hibrid nanomaterials

L. A. PÉREZ; G. I. LACCONI

Fortaleza

Congreso; XXV International Conference on Raman Spectroscopy; 2016

ICORS

The combination of carbon-based materials (graphene, graphene oxide, protein assemblies, etc.) with different nanostructures of metals, semiconductor oxides, organic compounds, etc. to obtain hybrid-materials is performed using simple chemical, electrochemical and photochemical methods. Owing to the additional functionality given regarding the individual materials offer unique physicochemical properties [1,2]. Currently, these nanomaterials are applied in optoelectronic devices, (bio) sensors of high sensitivity, catalysts, supercapacitors, antibacterial supports, superhydrophobic surfaces, etc. The functions of the new composite materials can be specifically predetermined depending on the desired application, through rational selection of its components. In this communication we show the characteristics of diverse hybrid systems, recorded with advanced microscopies (AFM-Raman, Imaging-Raman, SNOM, SERS, TERS, DRIFTS-contrast imaging, dark field imaging). A brief summary of the results is as follows: i) Platforms of AgNPs-protein assemblies. A SERS spectroscopic sensing platform for studying the interaction of Myristoylated Alanine-Rich C Kinase Substrate (MARCKS) protein with model membranes was prepared. The SERS substrate was designed by electrodeposition of Ag nanoparticles onto hydrogenated silicon. The chemical and structural characteristics of MARCKS molecules supported on this platform were examined under different configurations: a disordered distribution given by drop-casting and a compact monolayer transferred by the Langmuir-Blodgett method. Detection of specific vibrational bands from Phenylalanine (Phe), Lysine (Lys) residues and alpha helix structure related signals, have allowed establish direct interaction of the effector domain (ED) of MARCKS with the AgNPs surface on the platform.ii) Graphene oxide (GO) flakes decorated with AgNPs. An electrochemical strategy was employed for obtaining GO-Ag particles deposited on n-Si(111). The hybrid structures supported were built with assembled GO flakes, which were potentiodinamically electroreduced to induce active sites for silver nucleation. The colocalization of electrochemically-reduced GO (rGO) flakes and AgNPs was established by the correlation of AFM images and the spatial distribution of Raman signals (G and D bands and Ag-O stretching mode) in the mapping of the platform. Under certain potentiodynamic conditions, GO flakes completely coated with Ag, were obtained. They can be used as multifunctional hybrid platforms for catalysis, SERS detection, antimicrobial activity, microelectronic devices, etc.iii) GO-rGO hybrid pattern. GO/rGO hybrids were obtained with a controlled spatial reduction of a thick GO layer using laser radiation. The lithographic designs engraved on glass and silicon samples were characterized by Raman Imaging, where the observed changes in the Raman spectra were correlated with the localized chemical modifications on the nanomaterial. It has been found by AFM measurements that both thickness and roughness were diminished in the rGO region. Furthermore, we have demonstrated using SNOM that the optical features such as the refractive index of the irradiated region differs from the GO properties, effect which was also supported by Raman imaging results.iv) Network of graphene(CVD) and AuNPs . Experiments on CVD graphene-AuNps deposited on glass, show that the interaction between a 100 nm Au nanoparticle tip probe and the hybrid material give rise to dramatical (but reversible) changes in the graphene Raman spectra. Such as, an increase in the D band intensity due to reversible defects generation, and the blue shift of all the bands, produced by energy transfer from the hybrid structure to the Au tip [3]. The TERS results show with high resolution, the structural changes induced in graphene by the interaction with NPs. All resulting nanohybrids materials can be used as a trustworthy substrate for precise SERS chemical analysis. We have obtained topographical features, optical and molecular properties with high spatial resolution by a particular designed coupling of a Raman microscope (HORIBA Jobin Yvon HR) and a Multiview 2000 SNOM system (Nanonics).ACKNOWLEDGMENTSThis work was performed in close collaboration with: Graciela Borioli (CIQUIBICCONICET UNC), Florencia E. Lurgo (student Facultad Ciencias Químicas, UNC), Francisco Ibañez and Celeste Dalfovo (INIFTA-UNLP), Noelia Bajales Luna (IFEGCONICET UNC). All measurements were performed at Laboratorio de Nanoscopía y Nanofotónica of INFIQC-UNC (Córdoba, Argentina).REFERENCES[1] Chou SG, Ribeiro HB, Barros EB, Santos AP, Nezich D, Samsonidze GG, Fantini C, Pimenta MA, Jorio A, Plentz Filho F, Dresselhaus MS, Dresselhaus G, Saito R, Zheng M, Onoa GB, Semke ED, Swan AK, Ünlü MS, Goldberg BB, Chem. Phys. Lett. 2004, 397, 296-301.[2] Yin PT, Shah S, Chhowalla M, Lee K-B, Chem. Rev.2015; 115: 2483?2531. [3] Pérez LA, Dalfovo MC, Troiani H, Soldati AL, Lacconi GI, Ibañez FJ, J Phys.Chem. C 2016; 120: 8315-8322.