Electrochemically synthesized γ-Fe2O3 nanoparticles as peptide carriers and sensitive and reproducible SERS biosensors. Comparison of adsorption on γ-Fe2O3 versus Fe

Abstract Nontoxic to human γ-iron(III) oxide nanoparticles (γ-Fe2O3NPs) with ferrimagnetic and semiconductor properties, surface-functionalized with a peptide, can be useful as biosensors, drug-carriers, and therapeutic agents in MRI and hyperthermia. Surface-functionalized γ-Fe2O3NPs can protect tissue from damage caused by generation and attack of OH free radicals resulting from the exposure of Fe2O3 to visible light. Reducing the side effects of conventional therapy makes Fe2O3 a promising tool for the treatment of cancer. γ-Fe2O3NPs were synthesized in surfactant/ions-free aqueous solution on a new synthetic route, allowing control the size and morphology of the nanoparticles. γ-Fe2O3NPs were characterized by UV–vis, SEM-EDS, FTIR-ATR, Raman, XPS, XRD, Mossbauer, and DLS methods. It was shown that the aged nanoparticles were highly pure (γ-phase), well-crystallized, and had a spherical shape of an average diameter of 77 nm. γ-Fe2O3NPs were tested for their ability (i.) to adsorb Bombesin which occurs in the human body fluids and is known to induce tumor cell growth and (ii.) to promote the SERS effect. The SERS spectra on γ-Fe2O3 were compared to the SERS spectra on the α-Fe surface. The analysis was supported by SERS data for selected amino acids and BN immobilized on Cu, Au, Ag, Au@SiO2, and Ti.