Effect of Functionalized Multiwalled CNTs on the Selective Formation of Calcium Oxalate Crystals by Electrocrystallization

Abstract

The electrocrystallization (EC) of calcium oxalate (CaOx) crystals in the presence of multiwalled carbon nanotubes (MWCNTs) functionalized with itaconic acid (IA) and the monoester derivatives mono-methylitaconate or mono-octadecylitaconate, which were used as new IA-ester templates supported on indium tin oxide glass substrate as working electrode, was performed by applying a 9 mA current at 37 and 60 degrees C for 5 min. Under the above EC reaction conditions, a broad variety of CaOx morphologies and crystal forms was found. The morphology control and coexistence of CaOx monohydrate (COM) and CaOx dihydrate was achieved through in vitro EC according to X-ray diffraction spectra. We found that all the functionalized MWCNTs were more efficient inhibitors of CaOx crystallization than the typical citrate model, where MWCNT-IA was the most effective stabilizing template of COM crystals, because carboxylic acid groups of IA moieties in MWCNT-IA would be better Ca2+ ions binding sites than IA ester groups.