The sensing mechanism of GNP assemblies is based on the strong dependence of the charge transport through the films on external stimuli. Experimental studies of the conductivity of GNP films capped with alkanethiol ligands of different chain lengths in combination with structural investigations of the film structure using NMR and small-angle X-ray scattering (SAXS) revealed that the charge transport in these films occurs via thermally activated tunneling, whereby neighboring GNP cores are charged or uncharged by the tunneling electrons. The conductivity σ depends on the interparticle distance δ, the tunneling decay constant β, a pre-exponential tunneling factor σ 0 , and the activation energy E A that is required for charging the gold cores, σ(T, δ) = σ 0 e -δβ e -E A /RT .