The fusion dynamics is studied in heavy-ion collisions over wide range of neutron content (0.5 \le N/Z \le 2.0) by employing several different theoretical models such as Skyrme energy density model and proximity potential, as well as parameterized potentials due to Bass, Christensen and Winther, Ngô and Ngô and Denisov. We find that all these potentials give similar isotopic dependence for the fusion barrier heights, positions as well as cross-sections. Fusion barrier heights and positions follow a second order non-linear isotopic dependence whereas fusion cross-sections follow a linear dependence. The collision of neutron-deficient nuclei results into a reduced fusion cross-section whereas collision of neutron-rich nuclei leads to an enhanced fusion probability. The maximal isotopic dependence is obtained for the near barrier energies that reduces to insignificant level for higher incident energies. Our normalised observations are almost model independent indicating the universality in these predictions.

PACS numbers: 24.10.--i, 25.70.Jj, 25.60.Pj, 25.70.--z