Browsing by Author "Sarabia-Vallejos, Mauricio A."

Now showing 1 - 11 of 11
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    Antimicrobial polymers for additive manufacturing
    (2019) González Enríquez, Carmen; Sarabia-Vallejos, Mauricio A.; Rodriguez Hernandez, Juan
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    Biocompatible and bioactive PEG-Based resin development for additive manufacturing of hierarchical porous bone scaffolds
    (2023) Sarabia-Vallejos, Mauricio A.; Cerda-Iglesias, Felipe E.; Terraza, C. A.; Cohn-Inostroza, Nicolas A.; Utrera, Andres; Estrada, Manuel; Rodriguez-Hernandez, Juan; Gonzalez-Henriquez, Carmen M.
    Bone diseases can often result in patient bone fragility. Different bone problems include low bone density, osteoporosis, and other bone diseases. Such bone diseases, ailments, and malfunctions often require complex and expensive treatments. In this study, we synthesized a new type of DLP resin for 3D printing purposes based on poly(ethylene glycol diacrylate) (PEGDA) and acrylic acid (AAc). In addition, using a porogen within the photopolymerizable resin allowed us to fabricate hierarchical interconnected porous structures. These structures combine the pores resulting from the CAD design with those obtained by the lixiviation of the porogen. Finally, bioactive particles were added to the mixture to increase the material's biocompatibility, thus proving the strategy's potential to include active compounds for particular purposes. Our results demonstrate that including the photoabsorber, Orange G, considerably increases the printing precision and resolution of the synthesized resin, making it possible to obtain printed parts with intricate and complex geometries with high accuracy and definition. Nano-hydroxyapatite (nHA) inclusion significantly increases the material's biocompatibility and mechanical stiffness (similar to 47 % increase, from 5.47 MPa to 8.02 MPa).
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    Development of Soft Wrinkled Micropatterns on the Surface of 3D-Printed Hydrogel-Based Scaffolds via High-Resolution Digital Light Processing
    (2024) Sarabia-Vallejos, Mauricio A.; Romero De la Fuente, Scarlett; Cohn-Inostroza, Nicolás A.; Terraza Inostroza, Claudio Alberto; Rodriguez-Hernandez, Juan; González-Henríquez, Carmen M.
    The preparation of sophisticated hierarchically structured and cytocompatible hydrogel scaffolds is presented. For this purpose, a photosensitive resin was developed, printability was evaluated, and the optimal conditions for 3D printing were investigated. The design and fabrication by additive manufacturing of tailor-made porous scaffolds were combined with the formation of surface wrinkled micropatterns. This enabled the combination of micrometer-sized channels (100–200 microns) with microstructured wrinkled surfaces (1–3 μm wavelength). The internal pore structure was found to play a critical role in the mechanical properties. More precisely, the TPMS structure with a zero local curvature appears to be an excellent candidate for maintaining its mechanical resistance to compression stress, thus retaining its structural integrity upon large uniaxial deformations up to 70%. Finally, the washing conditions selected enabled us to produce noncytotoxic materials, as evidenced by experiments using AlamarBlue to follow the metabolic activity of the cells.
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    Fabrication and Testing of Multi-Hierarchical Porous Scaffolds Designed for Bone Regeneration via Additive Manufacturing Processes
    (2022) Gonzalez-Henriquez, Carmen M.; Rodriguez-Umanzor, Fernando E.; Acuna-Ruiz, Nicolas F.; Vera-Rojas, Gloria E.; Terraza-Inostroza, Claudio; Cohn-Inostroza, Nicolas A.; Utrera, Andres; Sarabia-Vallejos, Mauricio A.; Rodriguez-Hernandez, Juan
    Bone implants or replacements are very scarce due to the low donor availability and the high rate of body rejection. For this reason, tissue engineering strategies have been developed as alternative solutions to this problem. This research sought to create a cellular scaffold with an intricate and complex network of interconnected pores and microchannels using salt leaching and additive manufacturing (3D printing) methods that mimic the hierarchical internal structure of the bone. A biocompatible hydrogel film (based on poly-ethylene glycol) was used to cover the surface of different polymeric scaffolds. This thin film was then exposed to various stimuli to spontaneously form wrinkled micropatterns, with the aim of increasing the contact area and the material's biocompatibility. The main innovation of this study was to include these wrinkled micropatterns on the surface of the scaffold by taking advantage of thin polymer film surface instabilities. On the other hand, salt and nano-hydroxyapatite (nHA) particles were included in the polymeric matrix to create a modified filament for 3D printing. The printed part was leached to eliminate porogen particles, leaving homogenously distributed pores on the structure. The pores have a mean size of 26.4 +/- 9.9 mu m, resulting in a global scaffold porosity of similar to 42% (including pores and microchannels). The presence of nHA particles, which display a homogeneous distribution according to the FE-SEM and EDX results, have a slight influence on the mechanical resistance of the material, but incredibly, despite being a bioactive compound for bone cells, did not show a significant increase in cell viability on the scaffold surface. However, the synergistic effect between the presence of the hydrogel and the pores on the material does produce an increase in cell viability compared to the control sample and the bare PCL material.
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    Nanoreactors based on self-Assembled amphiphilic diblock copolymers for the preparation of ZnO nanoparticles
    (2013) Pizarro, Guadalupe del C.; Marambio, Oscar G.; González Enríquez, Carmen; Sarabia-Vallejos, Mauricio A.; Geckeler, Kurt E.
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    Polymers for additive manufacturing and 4D-printing: Materials, methodologies, and biomedical applications
    (2019) González Enríquez, Carmen; Sarabia-Vallejos, Mauricio A.; Rodriguez Hernandez, Juan
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    Smart Polymer Surfaces with Complex Wrinkled Patterns: Reversible, Non-Planar, Gradient, and Hierarchical Structures
    (2023) Sarabia-Vallejos, Mauricio A.; Cerda-Iglesias, Felipe E.; Perez-Monje, Dan A.; Acuña-Ruiz, Nicolás F.; Terraza Inostroza, Claudio Alberto; Hernández Rodríguez, Juan Andrés; González-Henríquez, Carmen M.
    This review summarizes the relevant developments in preparing wrinkled structures with variable characteristics. These include the formation of smart interfaces with reversible wrinkle formation, the construction of wrinkles in non-planar supports, or, more interestingly, the development of complex hierarchically structured wrinkled patterns. Smart wrinkled surfaces obtained using light-responsive, pH-responsive, temperature-responsive, and electromagnetic-responsive polymers are thoroughly described. These systems control the formation of wrinkles in particular surface positions and the reversible construction of planar-wrinkled surfaces. This know-how of non-planar substrates has been recently extended to other structures, thus forming wrinkled patterns on solid, hollow spheres, cylinders, and cylindrical tubes. Finally, this bibliographic analysis also presents some illustrative examples of the potential of wrinkle formation to create more complex patterns, including gradient structures and hierarchically multiscale-ordered wrinkles. The orientation and the wrinkle characteristics (amplitude and period) can also be modulated according to the requested application.
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    The role of three-dimensionality and alveolar pressure in the distribution and amplification of alveolar stresses
    (2019) Sarabia-Vallejos, Mauricio A.; Zuniga, Matias; Hurtado, Daniel E.
    Alveolar stresses are fundamental to enable the respiration process in mammalians and have recently gained increasing attention due to their mechanobiological role in the pathogenesis and development of respiratory diseases. Despite the fundamental physiological role of stresses in the alveolar wall, the determination of alveolar stresses remains challenging, and our current knowledge is largely drawn from 2D studies that idealize the alveolar septa! wall as a spring or a planar continuum. Here we study the 3D stress distribution in alveolar walls of normal lungs by combining ex-vivo micro-computed tomography and 3D finite-element analysis. Our results show that alveolar walls are subject to a fully 3D state of stresses rather than to a pure axial stress state. To understand the contributions of the different components and deformation modes, we decompose the stress tensor field into hydrostatic and deviatoric components, which are associated with isotropic and distortional stresses, respectively. Stress concentrations arise in localized regions of the alveolar microstructure, with magnitudes that can be up to 27 times the applied alveolar pressure. Interestingly, we show that the stress amplification factor strongly depends on the level of alveolar pressure, i.e, stresses do not scale proportional to the applied alveolar pressure. In addition, we show that 2D techniques to assess alveolar stresses consistently overestimate the stress magnitude in alveolar walls, particularly for lungs under high transpulmonary pressure. These findings take particular relevance in the study of stress-induced remodeling of the emphysematous lung and in ventilator-induced lung injury, where the relation between transpulmonary pressure and alveolar wall stress is key to understand mechanotransduction processes in pneumocytes.
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    Thermoresponsive microwrinkled hydrogel surfaces with modulated chemical composition
    (2021) Gonzalez-Henriquez, Carmen M.; Medel-Molina, Gonzalo E.; Rodriguez-Umanzor, Fernando E.; Inostroza, Claudio Terraza; Sarabia-Vallejos, Mauricio A.; Rodriguez-Hernandez, Juan
    Smart wrinkled hydrogel patterns with modulated chemical composition and wrinkle characteristics (amplitude and period) were formed by taking advantage of surface instabilities using a simple, cost-affordable, and robust method. The microstructured surfaces were prepared by dip coating and were designed to be stimuli-responsive by introducing poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) in the initial feed. For this purpose, a silylated substrate surface serves as an anchor for the non-polymerized hydrogel molecules, thus forming a homogenous and reproducible coating. Once the film was achieved, the samples were exposed to vacuum and UV irradiation to form wrinkled patterns spontaneously. The response of the thermosensitive wrinkles reveals significant variations in the properties of the wrinkled films depending on the temperature. In addition to the simplicity, this deposition strategy allows the preparation of highly reproducible films using an easy-scalable methodology with potential interest for industrial applications.
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    Three-Dimensional Whole-Organ Characterization of the Regional Alveolar Morphology in Normal Murine Lungs
    (2021) Sarabia-Vallejos, Mauricio A.; Ayala-Jeria, Pedro; Hurtado, Daniel E.
    Alveolar architecture plays a fundamental role in the processes of ventilation and perfusion in the lung. Alterations in the alveolar surface area and alveolar cavity volume constitute the pathophysiological basis of chronic respiratory diseases such as pulmonary emphysema. Previous studies based on micro-computed tomography (micro-CT) of lung samples have allowed the geometrical study of acinar units. However, our current knowledge is based on the study of a few tissue samples in random locations of the lung that do not give an account of the spatial distributions of the alveolar architecture in the whole lung. In this work, we combine micro-CT imaging and computational geometry algorithms to study the regional distribution of key morphological parameters throughout the whole lung. To this end, 3D whole-lung images of Sprague-Dawley rats are acquired using high-resolution micro-CT imaging and analyzed to estimate porosity, alveolar surface density, and surface-to-volume ratio. We assess the effect of current gold-standard dehydration methods in the preparation of lung samples and propose a fixation protocol that includes the application of a methanol-PBS solution before dehydration. Our results show that regional porosity, alveolar surface density, and surface-to-volume ratio have a uniform distribution in normal lungs, which do not seem to be affected by gravitational effects. We further show that sample fixation based on ethanol baths for dehydration introduces shrinking and affects the acinar architecture in the subpleural regions. In contrast, preparations based on the proposed dehydration protocol effectively preserve the alveolar morphology.
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    Wrinkling on Stimuli-Responsive Functional Polymer Surfaces as a Promising Strategy for the Preparation of Effective Antibacterial/Antibiofouling Surfaces
    (2021) Gonzalez-Henriquez, Carmen M.; Rodriguez-Umanzor, Fernando E.; Alegria-Gomez, Matias N.; Terraza-Inostroza, Claudio A.; Martinez-Campos, Enrique; Cue-Lopez, Raquel; Sarabia-Vallejos, Mauricio A.; Garcia-Herrera, Claudio; Rodriguez-Hernandez, Juan
    Biocompatible smart interfaces play a crucial role in biomedical or tissue engineering applications, where their ability to actively change their conformation or physico-chemical properties permits finely tuning their surface attributes. Polyelectrolytes, such as acrylic acid, are a particular type of smart polymers that present pH responsiveness. This work aims to fabricate stable hydrogel films with reversible pH responsiveness that could spontaneously form wrinkled surface patterns. For this purpose, the photosensitive reaction mixtures were deposited via spin-coating over functionalized glasses. Following vacuum, UV, or either plasma treatments, it is possible to spontaneously form wrinkles, which could increase cell adherence. The pH responsiveness of the material was evaluated, observing an abrupt variation in the film thickness as a function of the environmental pH. Moreover, the presence of the carboxylic acid functional groups at the interface was evidenced by analyzing the adsorption/desorption capacity using methylene blue as a cationic dye model. The results demonstrated that increasing the acrylic acid in the microwrinkled hydrogel effectively improved the adsorption and release capacity and the ability of the carboxylic groups to establish ionic interactions with methylene blue. Finally, the role of the acrylic acid groups and the surface topography (smooth or wrinkled) on the final antibacterial properties were investigated, demonstrating their efficacy against both gram-positive and gram-negative bacteria model strains (E. coli and S. Aureus). According to our findings, microwrinkled hydrogels presented excellent antibacterial properties improving the results obtained for planar (smooth) hydrogels.