Calculations of optical properties of some molecules suitable for coating of nanoparticles for biological applications

Coating of nanoparticles by various molecules is promising way to modify their surfaces and extend their bio-functionality, and infrared (IR), and spectroscopy of electronic transitions at ultraviolet and visible (UV/VIS) wavelengths are suitable techniques to investigate details of their attachment at nanoparticle surface. In the present work structure and optical properties of dextran, chitosan, oleic acid and poly(ethylene glycol) have been investigated by semi-empirical quantum mechanics, and ab initio Hartree–Fock calculations using the HyperChem® software package (http://www.hyper.com). The equilibrium conformations, IR, and UV/VIS spectra of molecules of various lengths, before and after their attachment to the magnetite (111) surface are determined, and IR modes and UV/VIS transitions that change the most upon the molecules attachment identified. The results are compared to the existing experimental data and the results of similar calculations, and possible implications for biological applications of nanoparticles coated with the investigated molecules have been discussed.