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Bioactive glasses belonging to the 56SiO2·(40 - x)CaO·4P2O5·xAg2O system, with x = 0, 2, and 8 mol %, were surface functionalized with the protein coupling agent glutaraldehyde (GA) and further evaluated in terms of hemoglobin affinity. The bare and GA-functionalized samples were investigated before and after protein attachment, by electron paramagnetic resonance (EPR) spectroscopy combined with spin-labeling procedure. Methanethiosulfonate spin label was used to explore the local environment of β-93 cysteine in horse hemoglobin, in terms of spin label side chain mobility. The EPR simulation methods were employed to quantify the rotational correlational times and fraction of the immobilized spin labels. The EPR absorption spectrum was further exploited to estimate the amount of hemoglobin loaded on the substrates. The surface elemental composition obtained by X-ray photoelectron spectroscopy revealed similar tendency in terms of surface coverage. Changes in surface architecture, that is, changes in surface morphology after protein coverage, were observed by scanning electron microscopy. It was concluded that GA improves the stability of protein attachment and induces polymerization of hemoglobin molecules.

The need to find new nanoparticles for biomedical applications is pushing the limits of the fabrication methods. New techniques with versatilities beyond the extended chemical routes can provide new insight in the field. In particular gas aggregation sources offer the possibility to fabricate nanoparticles with controlled size, composition and structure out of thermodynamics. In this context, the milestone is the optimization of the dispersion and functionalization processes of nanoparticles once fabricated by these routes as they are generated in the gas phase and deposited on substrates in vacuum or ultra-high vacuum conditions. In the present work we propose a fabrication route in ultra-high vacuum that is compatible with the subsequent dispersion and functionalization of nanoparticles in aqueous media and, that is more remarkable, in one single step. In particular, we will present the fabrication of nanoparticles with a sputter gas aggregation source, using a Fe 50 B 50 target, and their further dispersion and functionalization with polyethileneglycol (PEG). A characterization of these nanoparticles is carried out before and after PEG functionalization. During functionalization, significant boron dissolution occurs, which facilitates nanoparticle dispersion in the aqueous solution. The use of different complementary techniques allows us to prove the PEG attachment onto the surface of the nanoparticles creating a shell to make them biocompatible. The result is the formation of nanoparticles with a structure mainly composed by a metallic Fe core and an iron oxide shell, surrounded by a second PEG shell dispersed in aqueous solution. Relaxivitiy measurements of these PEG functionalized nanoparticles assessed their effectiveness as contrast agents for Magnetic Resonance Imaging (MRI) analysis. Therefore, this new fabrication route is a reliable alternative for the synthesis of nanoparticles for biomedicine.