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Your search keyword '"Rojas, Orlando J."' showing total 34 results
Start Over Author "Rojas, Orlando J." Journal acs applied materials & interfaces
34 results on '"Rojas, Orlando J."'

10. Fabrication and Characterization of Drug-Loaded Conductive Poly(glycerol sebacate)/Nanoparticle-Based Composite Patch for Myocardial Infarction Applications

Author

Zanjanizadeh Ezazi, Nazanin, primary, Ajdary, Rubina, additional, Correia, Alexandra, additional, Mäkilä, Ermei, additional, Salonen, Jarno, additional, Kemell, Marianna, additional, Hirvonen, Jouni, additional, Rojas, Orlando J., additional, Ruskoaho, Heikki J., additional, and Santos, Hélder A., additional

Published
2020
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14. Pickering Emulsions viaInterfacial Nanoparticle Complexation of Oppositely Charged Nanopolysaccharides

Author

Huan, Siqi, Zhu, Ya, Xu, Wenyang, McClements, David Julian, Bai, Long, and Rojas, Orlando J.

Abstract

We consider the variables relevant to adsorption of renewable nanoparticles and stabilization of multiphase systems, including the particle’s hydrophilicity, electrostatic charge, axial aspect, and entanglement. Exploiting the complexation of two oppositely charged nanopolysaccharides, cellulose nanofibrils (CNFs) and nanochitin (NCh), we prepared CNF/NCh aqueous suspensions and identified the conditions for charge balance (turbidity and electrophoretic mobility titration). By adjusting the composition of CNF/NCh complexes, below and above net neutrality conditions, we produced sunflower oil-in-water Pickering emulsions with adjustable droplet diameters and stability against creaming and oiling-off. The adsorption of CNF/NCh complexes at the oil/water interface occurred with simultaneous partitioning (accumulation) of the CNF on the surface of the droplets in net negative or positive systems (below and above stochiometric charge balance relative to NCh). We further show that the morphology of the droplets and size distribution were preserved during storage for at least 6 months under ambient conditions. This long-term stability was held with a remarkable tolerance to changes in pH (e.g., 3–11) and ionic strength (e.g., 100–500 mM). The mechanism explaining these observations relates to the adsorption of the CNF in the complexes, counteracting the charge losses resulting from the deprotonation of NCh or charge screening. Overall, CNF/NCh complexes and the respective interfacial nanoparticle exchange greatly extend the conditions, favoring highly stable, green Pickering emulsions that offer potential in applications relevant to foodstuff, pharmaceutical, and cosmetic formulations.

Published
2021
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16. Nanoarchitectonics of Nanocellulose Filament Electrodes by Femtosecond Pulse Laser Deposition of ZnO and In SituConjugation of Conductive Polymers

Author

Nguyen, Duong Tuan Anh, Wang, Ling, Imae, Toyoko, Su, Chun-Jen, Jeng, U-Ser, and Rojas, Orlando J.

Abstract

Electroactive filament electrodes were synthesized by wet-spinning of cellulose nanofibrils (CNF) followed by femtosecond pulse laser deposition of ZnO (CNF@ZnO). A layer of conducting conjugated polymers was further adsorbed by in situpolymerization of either pyrrole or aniline, yielding systems optimized for electron conduction. The resultant hybrid filaments were thoroughly characterized by imaging, spectroscopy, electrochemical impedance, and small- and wide-angle X-ray scattering. For the filaments using polyaniline, the measured conductivity was a result of the synergy between the inorganic and organic layers, while the contribution was additive in the case of the systems containing polypyrrole. This observation is rationalized by the occurrence of charge transfer between ZnO and polyaniline but not that with polypyrrole. The introduced conductive hybrid filaments displayed a performance that competes with that of metallic counterparts, offering great promise for next-generation filament electrodes based on renewable nanocellulose.

Published
2024
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19. Cellulose Nanofibril Film as a Piezoelectric Sensor Material

Author

Rajala, Satu, primary, Siponkoski, Tuomo, additional, Sarlin, Essi, additional, Mettänen, Marja, additional, Vuoriluoto, Maija, additional, Pammo, Arno, additional, Juuti, Jari, additional, Rojas, Orlando J., additional, Franssila, Sami, additional, and Tuukkanen, Sampo, additional

Published
2016
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33. On the Surface Interactions of Proteins with Lignin

Author

Salas, Carlos, Rojas, Orlando J., Lucia, Lucian A., Hubbe, Martin A., and Genzer, Jan

Abstract

Lignins are used often in formulations involving proteins but little is known about the surface interactions between these important biomacromolecules. In this work, we investigate the interactions at the solid–liquid interface of lignin with the two main proteins in soy, glycinin (11S) and β-conglycinin (7S). The extent of adsorption of 11S and 7S onto lignin films and the degree of hydration of the interfacial layers is quantified via Quartz crystal microgravimetry (QCM) and surface plasmon resonance (SPR). Solution ionic strength and protein denaturation (2-mercaptoethanol and urea) critically affect the adsorption process as protein molecules undergo conformational changes and their hydrophobic or hydrophilic amino acid residues interact with the surrounding medium. In general, the adsorption of the undenatured proteins onto lignin is more extensive compared to that of the denatured biomolecules and a large amount of water is coupled to the adsorbed molecules. The reduction in water contact angle after protein adsorption (by ∼40° and 35° for undenatured 11S and 7S, respectively) is explained by strong nonspecific interactions between soy proteins and lignin.

Published
2013
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34. Mesoscopic Simulations of the Phase Behavior of Aqueous EO19PO29EO19Solutions Confined and Sheared by Hydrophobic and Hydrophilic Surfaces

Author

Liu, Hongyi, Li, Yan, Krause, Wendy E., Pasquinelli, Melissa A., and Rojas, Orlando J.

Abstract

The MesoDyn method is used to investigate associative structures in aqueous solution of a nonionic triblock copolymer consisting of poly(propylene oxide) capped on both ends with poly(ethylene oxide) chains. The effect of adsorbing (hydrophobic) and nonadsorbing (hydrophilic) solid surfaces in contact with aqueous solutions of the polymer is elucidated. The macromolecules form self-assembled structures in solution. Confinement under shear forces is investigated in terms of interfacial behavior and association. The formation of micelles under confinement between hydrophilic surfaces occurs faster than in bulk aqueous solution while layered structures assemble when the polymers are confined between hydrophobic surfaces. Micelles are deformed under shear rates of 1 μs–1and eventually break to form persistent, adsorbed layered structures. As a result, surface damage under frictional forces is prevented. Overall, this study indicates that aqueous triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) (Pluronics, EOmPOnEOm) act as a boundary lubricant for hydrophobic surfaces but not for hydrophilic ones.

Published
2012
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