Browsing by Author "Laguna-Bercero, Miguel A."

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    Functionalization of Gold Nanostars with Cationic β-Cyclodextrin-Based Polymer for Drug Co-Loading and SERS Monitoring
    (2021) Donoso-Gonzalez, Orlando; Lodeiro, Lucas; Aliaga, Alvaro E.; Laguna-Bercero, Miguel A.; Bollo, Soledad; Kogan, Marcelo J.; Yutronic, Nicolas; Sierpe, Rodrigo
    Gold nanostars (AuNSs) exhibit modulated plasmon resonance and have a high SERS enhancement factor. However, their low colloidal stability limits their biomedical application as a nanomaterial. Cationic beta-cyclodextrin-based polymer (CCD/P) has low cytotoxicity, can load and transport drugs more efficiently than the corresponding monomeric form, and has an appropriate cationic group to stabilize gold nanoparticles. In this work, we functionalized AuNSs with CCD/P to load phenylethylamine (PhEA) and piperine (PIP) and evaluated SERS-based applications of the products. PhEA and PIP were included in the polymer and used to functionalize AuNSs, forming a new AuNS-CCD/P-PhEA-PIP nanosystem. The system was characterized by UV-VIS, IR, and NMR spectroscopy, TGA, SPR, DLS, zeta potential analysis, FE-SEM, and TEM. Additionally, Raman optical activity, SERS analysis and complementary theoretical studies were used for characterization. Minor adjustments increased the colloidal stability of AuNSs. The loading capacity of the CCD/P with PhEA-PIP was 95 +/- 7%. The physicochemical parameters of the AuNS-CCD/P-PhEA-PIP system, such as size and Z potential, are suitable for potential biomedical applications Raman and SERS studies were used to monitor PhEA and PIP loading and their preferential orientation upon interaction with the surface of AuNSs. This unique nanomaterial could be used for simultaneous drug loading and SERS-based detection.
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    Insights of the formation mechanism of nanostructured titanium oxide polymorphs from different macromolecular metal-complex precursors
    (2021) Allende, Patricio; Orera, Alodia; Laguna-Bercero, Miguel A.; Luisa Valenzuela, Maria; Diaz, Carlos; Barrientos, Lorena
    The insight into the mechanism of the unprecedented formation of pure anatase TiO2 from the macromolecular (Chitosan)center dot(TiOSO4)(n) precursor has been investigated using micro Raman spectroscopy, Scanning Electron Microscopy (SEM) and thermogravimetric/differential thermal analysis (TGA/DTA). The formation of a graphitic film was observed upon annealing of the macromolecular precursor, reaching a maximum at about 500 degrees C due to decomposition of the polymeric chain of the Chitosan and (PS-co-4-PVP) polymers. The proposed mechanism is the nucleation and growth of TiO2 nanoparticles over this graphitic substrate. SEM and Raman measurements confirm the formation of TiO2 anatase around 400 degrees C. The observation of an exothermic peak around 260 degrees C in the TGA/DTA measurements confirms the decomposition of carbon chains to form graphite. Another exothermic peak around 560 degrees C corresponds to the loss of additional carbonaceous residues.