Browsing by Author "Sarabia, Mauricio"

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    Crosslinked oxidized-nanocellulose/chitosan hydrogels as a scaffold matrix for mesenchymal stem cell growth
    (2024) Marino, Mayra A.; Oyarce, Karina; Tobar, Catalina; del Rio, Rodrigo Segura; Paredes, Maria G.; Pavez, Paulina; Sarabia, Mauricio; Amoroso, Alejandro; Concha, Jose L.; Norambuena-Contreras, Jose; Barjas, Gustavo Cabrera; Castano, Johanna
    Mesenchymal stem cells (MSC) are recognized for their immunomodulatory effects and regenerative properties, being promising therapeutic agents for a wide range of diseases. To ensure a localized effect of MSC in the organism biobased hydrogels have been tested for their ability to act as a matrix-embedded to improve MSC targeted delivery. In this context, nanocellulose (NC) has been used for drug delivery, showing biocompatibility and durability in time, but until now NC has not been tested for MSC growth exploiting the size and aldehyde content of NC. In this study, cellulose nanocrystals (CNC), cellulose nanofibers (CNF) and microfibrillated cellulose (MFC) were studied after one-pot oxidation and further crosslinking with chitosan (mass ratio 1:5). Size and aldehyde content of oxidized NC samples were evaluated to analyze their influence on the hydrogel's properties. The crosslinked hydrogels were analyzed by FESEM, swelling ability, FTIR, compression tests, thermal stability, and stability in culture cell conditions. Oxidized-MFC hydrogel improved the mechanical stability and swelling behavior, but it lacks stability at cell conditions possibly due to its low aldehyde content (0.54 mmol/g). Conversely, oxidized CNF and oxidized CNC formed suitable crosslinked hydrogels for cell adhesion, and for growing and proliferating of MSC 3D spheroids after 120 h. However, only hydrogel with PO-CNF/chitosan shows antibacterial activity as well as MSC proliferation.
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    Theoretical and Experimental Vibrational Spectroscopic Investigation of Two R1R2-Diphenylsilyl-Containing Monomers and Their Optically Active Derivative Polymer
    (2014) Gonzalez-Henriquez, Carmen M.; Terraza, Claudio A.; Sarabia, Mauricio
    FT-IR and Raman spectra of bis(4-aminophenyl)diphenylsilane (DIA) and a dicarboxylic acid containing the imide function and a L-alanine moiety (L-ALA) and their resultant polymer (PALA) were recorded in the 500-4000 cm(-1) and 400-3800 cm(-1) regions, respectively. The optically active poly(imide-amide) obtained has two sp(3) carbons in the main chain, favoring its flexibility. Raman analysis identifies the fluorescence produced by the electronic conjugation between the aromatic rings and the amidic groups, which affects the molecular fine structure. Thus, the theoretical study of the vibrational patterns has become a support and a complementary technique for the characterization of this fluorescent system. The optimized molecular geometry of the monomers and the polymeric unit using B3LYP and HF methods at the 6-31G(d) level of theory were used for the vibrational assignments. Thus, the small variations between the calculated and experimental vibration values could be related to possible intra- and/or intermolecular interactions or to the existence of a charge transfer phenomena between a donor or acceptor group within the system.