Rice engineers develop pH-sensitive peptide delivery system

Rice University engineers have invented a charge-based delivery system that lets gelatin carry therapeutic peptides more precisely to damaged tissue or tumors. The team embedded the peptides inside modified gelatin—collagen’s water-loving cousin—and tuned their release by switching the local charge from positive to negative. Early lab tests show the peptides stay locked inside until the pH drops or enzymes appear, then they slide out on cue.

Gelatin is cheap, biocompatible, and already used in sutures and sponges, but it has never been a reliable peptide courier because the molecules diffuse too fast or too slow. Rice’s trick is to graft small charged molecules onto the gelatin backbone; the peptides bind weakly when the charge is positive, then pop free when the environment turns negative. The change can be triggered by inflammation, infection, or even a mild acid flush—conditions common around wounds and certain cancers.

In pig-skin models, the charged gelatin kept a model peptide locked for more than two weeks at neutral pH but released 70 percent of it within 48 hours when the pH fell to 6.0, mimicking a chronic wound. The team measured no burst release and no toxic buildup in surrounding tissue. Collaborators at Baylor College of Medicine are now testing the same chemistry with an anti-inflammatory peptide in a mouse model of spinal-cord injury.

If the approach holds up, doctors could coat implants, bandages, or injectable gels with gelatin that only unloads its cargo when— and where—it’s needed. That could cut side effects, reduce dosing frequency, and open gelatin-based materials to peptides that were once too fragile or fast-acting to handle. The next step is scaling up synthesis and filing for an investigational-device exemption.