Interaction of biopolymers with graphene for bio-electronic applications

Molecular modelling concepts always prove to be an efficient technique for studying the interaction between various substances prior to experimental work. They were utilized for investigating the interaction of chitosan (Cs) and carboxymethyl cellulose (CMC) biopolymers with a modified graphene structure (G). Geometry optimization calculations were carried out using PM6 method. Results illustrate that the proposed interactions are all stable; however, the interaction site has no role in the resulting energy values. The calculated energies for the G-CMC interactions are quite lower than those for the G-Cs ones indicating quite higher stability for the former group. On contrary to energy, the proposed interaction active site has a significant part in determining total dipole moment (TDM) and hence reactivity of the structures. The calculated quantitative structure-activity relationship (QSAR) parameters show that the interaction of graphene with these biopolymers lowers its hydrophobicity. Modification of Cs and CMC with graphene has a significant positive impact on enhancing their electrical features. The resulting bandgap of the proposed structures is lower than half of their original values. Bandgap values of the G-CMC proposed structures are quite lower than those of the G-Cs ones. An experimental trial was carried out by printing a sixty-layer simple electrode of both biocomposite inks via InkJet printing technique. Then, Sheet resistance and charge mobility measurements were conducted. Results demonstrate that the sheet resistance of the G-Cs printed electrode is about five times higher than that of the G-CMC one. Such result was confirmed by the measured Hall Effect measurement which showed that the charge mobility in the G-CMC electrode is much greater than that in the G-Cs one. Both theoretical and experimental parts agree that the G-CMC biocomposite has much more electrical conductivity than the G-Cs, proposing it as a potential candidate for bio-electronic applications.