Electrochemical anodization of titanium produces uniform titania nanotube tops

The Goldilocks Effect

"This porridge is too hot!" Goldilocks exclaimed.
"This porridge is too cold," Goldilocks said.
"Ahhh, this porridge is just right," Goldilocks said happily.

Standard diffusion is driven by concentration gradients: when a high concentration solution is exposed to a lower concentration solution, molecules diffuse more quickly at first, in a burst, slowing as the concentration gradient reduces and the system comes to equilibrium. Unlike standard diffusion, nanoscale constrained diffusion does not exhibit concentration-driven kinetics. When molecules encounter pores that are slightly larger than the molecules themselves, diffusion is limited by the pore size. Molecules are forced to move through the pores only one at a time, producing linear release kinetics until the device is nearly empty.

The Pore Is Too Small

No Molecules Can Escape

Small pore

  • Zero Release

    When the pore size is smaller than the molecule itself, the molecule does not exit through the pore.

Small pore chart

  • Poor Delivery Profile

    No medication is delivered.

The Pore is Too Big

Molecules Exit Too Fast Too Soon

Big pore

  • Burst Release

    When the pore size is sufficiently large that molecules freely diffuse through the membrane, the rate of delivery decreases as the concentration equilibrates.

Big pore chart

  • Typical delivery profile of current treatments

    Medication is delivered at an uneven rate, potentially creating unnecessary side effects and limiting efficacy.

The Pore is “Just Right”

Molecules Leave at an Even Pace

Right pore

  • Constant Release

    When the pore size matches that of the molecule, constrained diffusion produces constant-rate release even as the concentration equilibrates across the membrane.

Right pore chart

  • Optimal delivery profile

    Medication is delivered at an even rate that eliminates concentration variability, potentially minimizing side effects and maximizing efficacy of treatment.

Visualize the Molecular Release

A Tale Of Two Pores

Burst Release of Molecules Much Smaller Than the Pore

NanoPortal-enabled Constant Release From Size-Matched Pores

Burst Release of Molecules Much Smaller Than the Pore

NanoPortal-enabled Constant Release From Size-Matched Pores

Tunable pore size makes drug delivery “just right”

NanoPortal incorporates a proprietary technique that enables nanometer-scale tuning to achieve pore sizes as small or large as necessary to produce constant release.
Sem small pores
Scanning electron microscope image of NanoPortal membrane with 10nm pores
Sem medium pores
Scanning electron microscope image of NanoPortal membrane with 25nm pores
Sem large pores
Scanning electron microscope image of NanoPortal membrane with 40nm pores
Injection Delivery Limitations
NanoPortal Technology