with ⟨N ± ⟩ = 4π a 0 dr r 2 n ± (r) and ⟨r 2 ⟩ ± = 4π a 0 dr r 4 n ± (r). We explicitly compute the microion density profiles from Poisson-Boltzmann (PB) theory. Assuming the cell to be in osmotic equilibrium with a microion reservoir of concentration 2n res , and considering Boltzmann distribution for the microions densities, n ± (r) = n res e ∓Φ(r) , with Φ(r) = β eψ(r) the reduced system electric potential, the Poisson equation is given by