Dr. Jorge Almodóvar, from the Department of Chemical Engineering of the University of Puerto Rico- Mayagüez will be offering a lecture titled "Engineering of Biopolymeric Nano Materials: from Fundamental Studies to Healthcare Applications".
Date: February 20, 2014
Time: 10:30 am – 12:00 pm
Place: INQU 004 - Amphitheater
The field of biomaterials emerged from the need of physicians for non-toxic materials to repair or replace damaged tissue, with a first generation of materials that at best were biologically inert. As the discipline began to draw engineers, chemists, biologists, and other experts of many fields a new class of biomaterials emerged, which instead of being inert, are now designed to stimulate specific cellular responses-in essence mimicking the native cell environment. One approach in engineering this new class of biomaterials is to design materials using macromolecules that are present in our bodies-such as proteins and polysaccharides. In this work, biopolymeric nano materials were developed for 1) fundamental studies in cell-material interactions and for 2) growth factor delivery for therapeutic purposes.
Layer-by-layer (LbL) films serve as a useful platform to investigate cell-material interactions, as several properties (chemistry, stiffness, protein loading, etc.) that are known to affect cellular behavior can be precisely tuned. In this context, the construction and characterization of polysaccharide-based LbL films, on flat surfaces, of different naturally derived polyelectrolytes are presented. An exhaustive spectroscopy study was performed. It was observed that thickness and swelling of these nanometer thick films depend on the charge density of the polyelectrolyte.
LbL films were then investigated for their potential to bind and deliver the basic fibroblast growth factor (FGF-2)-a powerful mitogen of mesenchymal stem cells (MSCs).Polysaccharide-based films were first constructed and characterized on flat surfaces. FGF-2 adsorption to films was monitored using IR spectroscopy, and its activity was assessed by investigating its mitogenic effect on MSCs. It was observed that MSC proliferation was enhanced when FGF-2 was delivered from the films. The versatility of the LbL process allows for the modification of more relevant biomaterials with complex structures. FGF-2 complexed to polysaccharide nano particles were adsorbed to and released from electrospun chitosan nanofibers. However, the fibers could be successfully modified withan LbL film, which prevents growth factor release while retaining its bioactivity.
The cell environment is a complex matrix that provides cells with both biochemical and physical cues in a spatial manner. To recreate this environment, gradients of matrix-bound growth factors and of stiffness were generated on biopolymeric LbL films by means of a microfluidic device. Cell adhesion and spreading decreased along the decreasing stiffness gradient. A matrix-bound gradient of the cytokine stromal derived factor 1 (SDF-1) was generated to investigate its effect on cellular migration. Time-lapse microscopy showed that cellular velocities decreased with decreasing SDF-1 concentration. A matrix-bound gradient of the bone morphonogenetic protein 2 (BMP-2) was generated to investigate muscle cell trans-differentiation in bone cells. Cells responded by expressing the bone differentiation marker alkaline phosphatase in a spatially controlled manner. Moreover, on regions of low BMP-2 concentration, a dose-dependent expression of myoblastic markers was observed. Lastly, in view of a therapeutic approach, LbL films were successfully deposited on a cellular bone allografts. The films on bone support mammalian cell growth and showed antimicrobial properties.
This works demonstrates how biopolymeric nano materials can be finely engineered for fundamental studies (cell/material interactions, growth factor presentation, control of cellular processes) and for therapeutic applications. The can be used in simple systems (flat surfaces) or applied to complex structures. Moreover, more biomimetic systems can be created with these strategies by generating materials with gradients in properties. These biomaterials show great promise in tissue engineering applications.
Jorge Almodóvar earned his B.S. in Chemical Engineering from Iowa State University in 2007. He then enrolled in Colorado State University where he earned his Ph.D. in Chemical Engineering under the supervision of Prof. Matt Kipper in 2011. At CSU he investigated the delivery and stability of growth factors using polysaccharide-based biomaterials. After CSU, he worked as a Post-Doctoral Fellow at the Grenoble Institute of Technology under the supervision of Prof. Catherine Picart in Grenoble, France investigating the formation of gradients on polyelectrolyte multilayer films, funded by the Whitaker International Program. Currently he is an assistant professor of the Chemical Engineering Department at the University of Puerto Rico-Mayagüez. His research interests include extracellular matrix mimetic biomaterials, cell-material interactions, and growth factor delivery. He plans to develop a research team focusing on the engineering of biomimetic materials—inspired by the native cell environment—for fundamental studies, therapeutics, and regenerative medicine.