The resulting dispersion was then homogenised and transferred into four sterile 50 mL centrifuge tubes, which were vortexed for a few seconds at maximum speed and centrifuged at 9000 rpm for 20 minutes. The supernatant was discarded, but its pH was measured. The graphitic pellet was then redispersed in fresh water for injections and the centrifugation steps were repeated multiple times (usually about 6 cycles) until a neutral pH was obtained in the supernatant. This was also characterised by the formation of an orange, gel-like layer at the interface between the pellet and the supernatant. Details regarding the temperature conditions of the different centrifuge cycles as well as vortex duration time were provided in a previous publication from our group . Mechanical exfoliation of GO was performed by vortexing for 5 minutes at maximum speed, followed by centrifugation, which led to the accumulation of thin GO flakes on top of the black graphitic debris. The orange layer was then solubilised in warm water for injections and carefully collected while avoiding remixing with the pellet. Eventually, a brownish aqueous solution containing highly dispersible, large graphene oxide flakes (l-GO) was obtained. The remaining graphitic impurities were removed 24 hours post-reaction after an ultimate centrifugation cycle at 9000 rpm for 20 min at 20ºC. GO was freezedried for 3 days, in order to estimate the concentration of l-GO before reconstituting in the same volume of water for injections for sonication.