Freezone 2

All surfactants were synthesized as described previously. 32, 39 In brief, 1 mol equivalent of Krytox FSH 157 (~6500 Da, Chemours, USA) was dissolved at 0.1 g mL--1 in Novec HFE--7100 (3M, USA).
The reaction was performed under argon using dry glassware.
The carboxylic end group of the Krytox Please do not adjust margins Please do not adjust margins and removed the top layer. This washing step was repeated three times before the surfactant was dried using a rotary evaporator (Hei--VAP, Heidolph, Germany) and a freeze dryer (FreeZone 2.5, Labconco, USA).

Materials & synthesis of rGO foams 'Highly concentrated' GO was purchased from Graphenea, as a gel at 2.5 wt%, with 495% monolayer content as measured at 0.05 wt%.
An aqueous colloidal dispersion of GO was diluted with de-ionised (DI) water into a dispersion of the desired wt%. DI water was used to introduce as few impurities and ionised particulates into the foams as possible. Impurities in the precursor dispersion, which could be introduced by using non-DI water, could impact both the mechanical and electrical properties of the resulting foam scaffolds as well as providing the potential for toxicity to the cells under study. The diluted precursor dispersion was then cast into a mould of desired geometry, frozen in a conventional freezer at approximately À18.5 1C, and lyophilised with a Labconco 'FreeZone 2.5' into a low-density foam. This mould-based liquid processing means that there is in principle no limit to the size and shape of the sample, which is beneficial when designing a scaffold for a specific application. After synthesis, the GO foams were thermally reduced into rGO for three hours at low pressure, P E 1 mBar, and set temperature T = 150 1C in a Memmert vacuum oven. This procedure is detailed schematically in Fig. 1. Reduction was undertaken until no further change in conductivity was observed and the samples had recovered a metallic lustre (Fig. S1,ESI †).