Risk and life cycle assessment of nanoparticles for medical applications prepared using safe- and benign-by-design gas-phase syntheses

Laser vaporisation is a promising technology for the industrial manufacturing of spherical, oxidic nanoparticles, including crystalline, less-agglomerated ferromagnetic maghemite (γ-Fe2O3) and superparamagnetic γ-Fe2O3/amorphous SiO2 composite nanoparticles. These can be utilised in medical applications such as contrast agents in magnetic resonance imaging (MRI) and may replace common contrast agents such as gadolinium chelate complexes. Nano-specific risk assessment and life cycle assessment have been used in parallel in order to critically assess benefits and shortcomings of this technological approach and to find the key parameters for process optimisation. Potential risks in occupational safety were found to be low, but the energy demand of the laser system is crucial in terms of environmental impact potential. However, process optimisation options in process efficiency, laser source and reuse of waste heat were identified, leading to a decrease of the overall cumulated energy demand up to 94%. Flame spray pyrolysis was included in the comparative study as an alternative approach for gas phase synthesis of oxidic nanoparticles. Both technologies and the resulting nanoenabled products were found to be environmentally beneficial compared to the preparation of the standard MRI contrast agent Gadovist®.