Studies on the structure and electronic properties of Linear Chitosan-Silver nano-composite for biosensor applications

In the present study, we computed the geometrical and electrical influence of silver atoms (Ag) over chitosan (CS). The electrical influences were studied through analyzing the electrostatic potential map, the HOMO-LUMO orbitals, and the energy gap. Three systems were simulated for this study. They are, pure chitosan (CS), chitosan with one silver atom (CS-Ag) and chitosan with three silver atoms (CS-3Ag). The theoretical calculations were done using Density Functional Theory (DFT) at B3LYP level set theory with SBKJC basis set to obtain the structure and energetic properties of the systems. Our calculations confirmed that Ag atoms have minimal effect on the geometry of CS. Further, the simulation suggests that the interaction between Ag atoms and CS is due to purely a Van der Waals interactions on most of the electro-positive sites. On the other hand, the HOMO-LUMO orbitals of CS-Ag and Cs-3Ag show a higher density near to the Ag atoms, which result in a reduction of the energy gap. Finally, the antibacterial properties of CS and Ag combined with the low energy gap suggest that CSAg nano composite (CS-AgNc) could be a suitable nanomaterial for bio-sensing applications.