An experimental and theoretical approach to investigate correlation between electromagnetic properties of doped ferrites & its interfacial reactivity with dopamine

Magnetic nanoparticles have attained considerable attention in the field of biomedicine. It can acquire single magnetic domain when particle size is scaled down to few nanometers and exhibit high coercivity and magnetization. At diameter less than 30 nm it exhibits superparamagnetism which makes it an attractive candidate for biosensing, magnetic resonance imaging and targeted drug delivery applications. However colloidal instability limits its application. The use of bifunctional linkers not only stabilizes nanoparticles but also provides one-step synthesis system in which linker has an attachment site for magnetic nanoparticles and another site bearing COOH⁻/NH₂ ⁺ which allows binding of functional proteins or drugs. In this study, we selected dopamine for functionalization of Magnetite, Cobalt and Zinc Ferrite nanoparticles to understand how introduction of bivalent cations affects the chemisorption properties. Changes in its interfacial reactivity towards dopamine were first determined theoretically and interacting species were identified through Fourier Transform Infra-red Spectroscopy/FTIR. Dopamine binds with Fe⁺² at octahedral positions through its -OH group in bidentate bridging configuration while addition of Zn⁺² shifts its reactivity towards amine groups. A correlation between interfacial reactivity & electromagnetic properties of doped Iron oxides determined using combinations of pseudopotential and relativistic treatment methods, has also been established.