Publications

Recent studies have revealed that cardiac tissue regeneration is promoted by administering an initial dose of exogenous lactate and locally maintaining an abundant concentration of this compound for a prolonged period (i.e., around 10-14 days) through sustained release. The aim of this study is to develop a scaffold based on poly(lactic acid) (PLA) for achieving a sustained daily release of lactate from the first day to the end of the recommended period. First, a five-layered electroresponsive scaffold has been engineered using three PLA layers (first, third, and fifth), each composed of electrospun microfibers (MFs), separated by spin coated lactate (second) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (fourth) intermediate layers. The hydrophobicity of the outer PLA layers (first and fifth) has been used to maintain the release of lactate from the intermediate second layer over 3 days, while the conducting fourth PEDOT:PSS layer has ensured a complete lactate release by electrostimulation. After that, in a second step, the same scaffold has been re-engineered to maintain the sustained release not only for a short period (3 days) but also for a prolonged period (>10 days). For this purpose, the PLA MFs of the intermediate third layer have been substituted by plasma-treated proteinase K-containing PLA MFs, obtained by electrospinning a PLA:enzyme mixture. The activity of the enzyme, which decomposes the ester bonds of PLA, combined with the effect of the plasma on the PLA structure, results in a prolonged sustained release that, in addition, can be modulated.

JTD Keywords: 4-ethylenedioxythiophene), Cardiac tissue regeneratio, Conducting polymer, Drug-release, Electroresponsivescaffolds, Electrospinning, Energy, Enzymatic degradation, Hydrogel, Nanofibers, Poly(3, Poly(lactic acid), Raman-spectroscopy

Polymeric membranes exhibit unique and modulate transport properties when they are properly functionalised, which make them ideal for ions transport, molecules separation and molecules interactions. The present work proposes the design and fabrication of nanostructured membranes, composed by biodegradable poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG), incorporating a lipophilic molecule (cholesterol) covalently bonded, were especially designed to provide even more application opportunities in sensors field. Electrochemical studies, by means of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV), revealed important differences regarding the functionalised and non-functionalised PLA systems. PEGcholesterol building block units showed a clear affinity with ascorbic acid (vitamin C) and Trolox (R) (a watersoluble analogue of vitamin E), both hydrophilic in nature, with a limit of detection capacity of 8.12 mu M for AA and 3.53 mu M for AA and Trolox, respectively, in aqueous salt solution. The bioinspired polymer may be used to incorporate antioxidant property that allow the design of anti-stress biosensors, electrodes for the detection of vitamin C or vitamin E in biomedical nutrition programs, among other applications.

JTD Keywords: Antioxidant molecules, Antioxidants, Application programs, Ascorbic acid, Biomimetics, C (programming language), Capacity, Chemical detection, Cholesterol, Cyclic voltammetry, Electrochemical detection, Electrochemical impedance spectroscopy, Functional polymers, Functionalized, Lactic acid, Molecules, Nanomembranes, Poly ethylene glycols, Poly lactic acid, Poly(ethylene glycol), Poly(ethyleneglycol), Poly(lactic acid), Polyethylene glycols, Vitamin-e

A study of the shape memory effect on extruded polylactic acid (PLA) and polycaprolactone (PCL) blends, which were transformed into films and movable components of articulated specimens by hot pressing and 3D printing, respectively, is presented. After characterizing their chemical structure by FTIR spectroscopy and their wetta-bility, the thermal properties and mechanical response of the blends were evaluated and compared with those of neat PLA and PCL. The blends exhibited very good interfacial adhesion between the phases, even though they are immiscible polymers. The thermoresponsive shape memory effects of neat PLA, neat PCL and PLA/PCL blends with different compositions (90/30, 70/30 and 50/50 w/w%) were evaluated considering three consecutive heating-cooling cycles. Comparison of the initial permanent state geometry with the geometries achieved after each heating-cooling cycle for both films and 3D printed specimens, evidenced that the 70/30 w/w% blend exhibited the best behavior. Thus, the blends obtained with such composition showed the maximum reversibility between the temporary and permanent states (i.e. highest shape recovery capability) and shape fixing of such two states.

JTD Keywords: 3d printing, Fibers, Films, Poly(lactic acid), Polycaprolactone, Polylactic acid, Polymer, Shape fixing, Shape-memory polymers, Unimolecular micelles

PLA MPs are prepared via a novel and toxic-chemical-free fabrication route using ethyl lactate, a green solvent and FDA-approved aroma. MPs are obtained by a solution jet break-up and solvent displacement method. Adjusting flow parameters allows the tuning of MPs size between 60 and 180 µm, with reduced polydispersity. Morphological analysis shows microporous particles with Janus-like surface. A fluorophore is successfully loaded into the MPs during their formation step. This versatile green solvent-based procedure is proven to be suitable for drug encapsulation and delivery applications. The method may be extended to different droplet generation techniques.

JTD Keywords: Biocompatibility, Biodegradable, Green solvents, Microparticles, Poly(lactic acid)