Alberto Rainer

Composite Ormosil/Nafion Membranes as Electrolytes for Direct Methanol Fuel Cells

Composite Ormosil/Nafion membranes were prepared and characterized for use as electrolytes in direct methanol fuel cells (DMFCs). An organosilane derivative (sulfonated diphenylsilanediol, SDPSD) was selected as a filler of the Nafion matrix. The composite membranes were characterized by electrochemical impedance spectroscopy, differential scanning calorimetry, and solvent uptake measurements. The composite membranes exhibited higher proton conductivity and enhanced stability than the reference unfilled Nafion membrane, due to the occurrence of an effective interaction between the filler and the polar cluster of the polymer matrix. Polarization curves in a DMFC were acquired and the results showed that the performance of the composite membrane was superior to that of unfilled Nafion due to a reduced methanol permeation rate, as well as to enhanced proton conductivity and thermal stability of the membrane. Due to its satisfactory properties, the composite Nafion/SDPSD membrane has a potential use as electrolyte in DMFCs operating at intermediate temperatures.

Electrospun Nanocomposites and Stem Cells in Cardiac Tissue Engineering

Stem cell therapy is a leading field of research worldwide given its promising potential for recovery or replacement of tissues and organs, especially for the treatment of cardiovascular pathologies. However, despite this enormous experimental effort and the reported positive results in different models, there is no conclusive demonstration of the mechanisms involved in tissue regeneration associated to adult stem cell treatment. This represents one of the major limitations for the clinical translation of stem cell therapy. A real regenerative medicine approach should consider the importance of the extracellular matrix (ECM) and the strong biological signals that it can provide. Connective tissue atmosphere in which cells are embedded exerts a number of actions affecting cells function and supporting their proliferation and differentiation. Polymeric electrospun matrices are among the most promising ECM-mimetic biomaterials, because of their physical structure closely resembling the fibrous proteins in native ECM. Moreover, electrospun materials can be easily functionalized with bioactive molecules providing localized biochemical stimuli to cells seeded therein. The idea of taking advantage of both stem cells plasticity and biomaterials that actively guide and provide the correct sequence of signals to allow ongoing lineage-specific differentiation is an attractive alternative and may represent a promising answer to the treatment limitations of cardiovascular severe diseases.

Muscle Reconstruction and Regeneration Using Biodegradable Scaffolds

The complete loss or weakening of anatomically defined muscular structures may be determined by many pathological states and may lead to high morbidity and clinical expense. Attempts to functionally correct them have encountered limited success. On the account of more demanding requirements of materials for the myofascial repair, we evaluated a bioabsorbable polymer mimicking, at the structural level, the characteristics of the native extra cellular matrix (ECM). A described model of muscle injury was used, consisting in the generation of a large abdominal wall defect in 20 Wistar rats. Ablated rectus abdominis was repaired with electro spun poly-L-lactide (PLLA) acellullar patch. Evaluation of the newly developed ECM showed a more delicate fibrillar and organized collagen network in the PLLA group in comparison to control indicating a more advanced process of wound remodeling and a more controlled and modulated tissutal reaction. Scaffold elicited a potent angiogenic response with the appearance of CD31 positive vessels. Additionally, the graft hosted CD34 positive cells, reliable sign of organism response to muscle injury. The biomimesis principle inspiring the structure of this scaffold guided a reparative processes and modulated the microenvironment of the damaged tissue, favoring the regenerative drive over the inflammatory reaction.

A 3D ECM-Mimicking Device to Assess Stem Cells Differentiation: A Novel Approach to Stemness Evaluation

Stem cell therapy is considered a leading field of research worldwide, attracting a stunning amount of clinical applications, given its promising potential for recovery or replacement of tissues and organs. The idea of combining principles from cell biology and engineering of biocompatible materials in order to create biologic replacement structures that restore, maintain, or improve tissue function, is at the basis of the so called “Tissue Engineering” area, a new emerging avenue in regenerative medicine. On account of the more demanding requirements for the use of stem cells in clinical settings and of the constant description of new stem cells types, the authors developed a functional biological assay, based on 3D ECM-mimicking supports, for the assessment of differentiative potential of candidate bone marrow-derived cells towards chondrocytic, vascular and muscular phenotypes.

Co-Sintering of Dense Electrophoretically Deposited YSZ Films on Porous NiO-YSZ Substrates for SOFC Applications

An original process for the preparation of YSZ dense films with a thickness lower than 10 µm over NiO-YSZ substrates is presented. This process involves the preparation of a green membrane of NiO-YSZ and subsequent electrophoretic deposition (EPD) of commercial YSZ powder on this polymer-rich membrane. A single thermal treatment allowed removal of the organic compounds, sintering of the layers and full densification of the electrolyte.