Juan Silva

Control of calcium oxalate morphology through electrocrystallization as an electrochemical approach for preventing pathological disease

AbstractPathological crystallization of calcium oxalate (CaOx) inside the urinary tract is called calculi or kidney stone (Urolithiasis). CaOx exhibits three crystalline types in nature: CaOx monohydrate COM, dihydrate COD and trihydrate COT. COD and COM are often found in urinary calculi, particularly COM. Electrocrystallization has been recently used to perform oriented crystallization of inorganic compounds such as Ca-salts. Although many mineralization methods exist, the mechanisms involved in the control of CaOx polymorphism still remain unclear. Herein, we induced selective electrocrystallization of COD by modifying the electrical current, time and electrochemical cell type. By combining above factors, we established an efficient method without the use of additives for stabilizing non-pathological CaOx crystals. We found notorious stabilization of CaOx polymorphisms with hierarchically complex shape with nano-organization assembly, size and aggregated crystalline particles. Our results demonstrated that, by using an optimized electrochemical approach, this technique could have great potential for studying the nucleation and crystal growth of CaOx through functionalized synthetic polymers, and to develop a novel pathway to evaluate new calculi preventing-compound inhibitors. Graphical abstractElectrocrystallization set-up for modifying the morphology and crystal growth of CaOx particles.

Polyaniline nanostructure electrode: morphological control by a hybrid template

We report here a novel approach to the template-assisted electrochemical synthesis of vertically aligned polyaniline (PANI) nanostructure surface arrays. When PANI is obtained by electropolymerization inside a custom-made anodic aluminum oxide (AAO) template, with an Au layer sputtered onto one side of the AAO acting as an anode, PANI nanotubes are obtained. In contrast, when the surface of this gold layer is modified with 4-aminothiophenol (4-ATP) as a self-assembled monolayer (SAM) film anchored to the gold layer via the thiol groups and on the opposite end having NH2 functionalities, we obtain a surface array of PANI nanowires. Cyclic voltammetry and SEM analysis show that the amino functionalities of Au/SAMs act as a nucleation site in the internal base of the AAO pore and determine both the morphology and structure of polyaniline and its electronic properties as well.