Micro-Raman study of the role of sterilization on carbon nanotubes for biomedical applications

Aim: We investigate the effect of four different types of sterilization procedures on the structural properties and morphological features of single-wall carbon nanotube samples approachable by micro-Raman spectroscopy. Sterilization procedures (treatment in humid heat autoclave or ethylene oxide and irradiation with gamma-rays or UV light) are necessary in view of the use of carbon nanotube sterile samples in in vivo toxicity tests on laboratory rats. Micro-Raman spectroscopy allows us to estimate several details about the morphology of the single-wall carbon nanotube mixture (mainly the presence of disorder and diameter distribution) before and after the sterilization treatment. Results: The best of these treatments, in other words, the one that least affected the morphology and structural properties of carbon nanotubes, was found to be UV irradiation and has thus been selected for future in vivo tests on rats.