[ 18 ] Hence, at the initial time due to a higher concentration gradient, there is a sudden release of these molecules. This phenomenon has a strong clinical implication, such as for implants with a drug-eluting surface, a sudden release may agitate the local environment and can result in an undesirable host-cell response. However subsequently the initial burst release gives way for a more gradual zero-order release kinetics . This typical biphasic release behavior is also observed from our structures as shown in Fig 6 . However, comparing the release pattern from the three platforms there are differences in their behaviors in terms of the initial burst release and the total release rate and time. The release characteristics reveal a variation in the initial burst (i.e., the percentage release after 4 hours), the initial release reduced from 28 % to 16 % for the H -ZrNT and M 2 -ZrNT, respectively. A possible explanation can be linked to the structural variation; in the H -ZrNT with a higher pore size of 80 nm ± 20 nm would result in a reduced restriction to immediate interaction with a larger influx volume with the solvent compared to the modulated structures with a pore diameter of 30 nm ± 20 nm where more restriction to diffusion is expected. This result is in good agreement with previously cited publications on other investigated structurally similar delivery systems like TiNT and NAA where experiments reported by Losic et al had shown that by reducing the pore size of the nanotube the initial burst release was inhibited.