Browsing by Author "Isaacs, Mauricio"
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- ItemCdTe quantum dots modified electrodes ITO-(Polycation/QDs) for carbon dioxide reduction to methanol(ELSEVIER, 2020) Guzman, Diego; Isaacs, Mauricio; Tsukuda, Tatsuya; Yamazoe, Seiji; Takahata, Ryo; Schrebler, Ricardo; Burgos, Ana; Osorio Roman, Igor; Castillo, FranciscoThe present work describes the characterization by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques of ITO modified electrodes with electrostatic assemblies (Polycation/Quantum Dots) and their use in the electro- and photoelectrocatalytic reduction of CO2. These assemblies were prepared with polycations poly-diallyldimethylammonium (PD) and poly-(2-trimethylammonium) ethyl methacrylate (PM) and nanocrystals of CdTe of 2.77 nm (Q2). The size of the nanocrystals was controlled by the synthesis reflux time and incorporated by electric field directed Layer-by-Layer assembly method (EFDLA). The polycations were characterised by NMR measurements; showing important effects on the electrostatic assemblies. PM modified electrodes, with its lower rigidity, exhibited less roughness than the PD modified electrodes, 8.0 nm versus 32.8 nm, and higher heterogeneity in its surface composition. Higher resistance to the charge transfer and time constants were obtained with PMQ2 modified electrode, 63.8 Omega cm(-2) and 2.69 ms versus 49.30 Omega cm(-2) and 1.3 ms for PDQ2. The electro- and photoelectro properties for CO 2 reduction were studied through j-E curves and potential controlled electrolysis. Modified surfaces were active toward the reduction of CO2, with a positive shift of the activity between darkness and irradiation conditions, 0.050 V with PDQ2 and 0.450 V with PMQ2. The main product of the CO2 reduction was CH3OH, with traces of CO and HCOOH. The PM modified electrodes with QDs of 2.77 nm presented a selective behaviour for the production of CH3OH.
- ItemImproving myoblast differentiation on electrospun poly(ε-caprolactone) scaffolds(2017) Abarzua-Illanes, Phammela N.; Padilla, Cristina; Ramos, Andrea; Isaacs, Mauricio; Ramos Grez, Jorge; Olguin, Hugo C.; Valenzuela, Loreto M.
- ItemMultimetallic porphyrins/polyoxotungstate modified electrodes by layer-by-layer method: Electrochemical, spectroscopic and morphological characterization(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Garcia, Macarena; Carfuman, Karla; Diaz, Carlos; Garrido, Carlos; Osorio Roman, Igor; Jesus Aguirre, M.; Isaacs, MauricioThis work describes the formation of modified electrodes layer-by-layer assembly of a mu-{meso-5,10,15,20-tetra(pyridyl)porphyrin}terrakis{bis(bipyridine)chloride ruthenium(II)} coordinated with Zn(II) and Mn(III) in its central cavity and an anionic polyoxotungstate [SiW12O40](4-). The bilayer formation was monitored using electrochemical and UV-vis techniques, following the oxidation process of the Ru-III/II couple and the absorbance of the Soret band of porphyrin complexes respectively. It was possible to form 10 stable bilayers onto ITO surface. SEM studies were carried out finding that the morphology of the film depends on the metal center in the porphyrin. The thickness of these films was estimated as 0.603 mu m for (Zn(II)TRP](4+)/[SiW12O40](4-) and 2.18 mu m for [Mn(III)TRP](5+)/[[SiW12O40](4-) modified electrodes respectively. Raman spectroscopy showed that new bands appeared for [Mn(III)TRP](5+)/[SIW12O40](4-) assembly confirming stronger interactions than only electrostatic forces.
- ItemPhenoxy- and Phenylamino-Heterocyclic Quinones: Synthesis and Preliminary Anti-Pancreatic Cancer Activity(WILEY-V C H VERLAG GMBH, 2022) Sanchez, Patricio; Salas, Cristian O.; Gallardo-Fuentes, Sebastian; Villegas, Alondra; Veloso, Nicolas; Honores, Jessica; Inman, Martyn; Isaacs, Mauricio; Contreras, Renato; Moody, Christopher J.; Cisterna, Jonathan; Brito, Ivan; Tapia, Ricardo A.The successful application of fragment-based drug discovery strategy for the efficient synthesis of phenoxy- or phenylamino-2-phenyl-benzofuran, -benzoxazole and -benzothiazole quinones is described. Interestingly, in the final step of the synthesis of the target compounds, unusual results were observed on the regiochemistry of the reaction of bromoquinones with phenol and aniline. A theoretical study was carried out for better understanding the factors that control the regiochemistry of these reactions. The substituted heterocyclic quinones were evaluated in vitro to determine their cytotoxicity by the MTT method in three pancreatic cancer cell lines (MIA-PaCa-2, BxPC-3, and AsPC-1). Phenoxy benzothiazole quinone 26a showed potent cytotoxic activity against BxPC-3 cell lines, while phenylamino benzoxazole quinone 20 was the most potent on MIA-PaCa-2 cells. Finally, electrochemical properties of these quinones were determined to correlate with a potential mechanism of action. All these results, indicate that the phenoxy quinone fragment led to compounds with increased activity against pancreatic cancer cells.