ACS Meeting News: A pH-Sensitive Polymer Could Lead To Long-Term Drug Delivery Devices

A new family of polymers could help fight obesity and antibiotic resistance just by falling apart.

Researchers led by Giovanni Traverso of the Massachusetts General Hospital and Robert Langer of Massachusetts Institute of Technology have synthesized hydrogels that are stable in stomach acid, but dissolve in the neutral pH of the intestines (Nat. Mater. 2015, DOI:10.1038/nmat4355).

These materials will enable researchers to develop safer gastric resident devices, which live in patients’ stomachs for extended periods of time, said Shiyi Zhang. Zhang is a postdoc on the research team who presented the work Wednesday at the American Chemical Society national meeting in Boston during a session hosted by the Division of Polymeric Materials: Science & Engineering.

Doctors implant devices that can help supplement a patient’s nutrition and curb appetite. But these devices can fail in the stomach and fall into patients’ intestines, where they stay until someone retrieves them—usually surgically.

Devices made using the new polymer could break up into smaller parts that patients could pass without any surgical intervention. The research team designed the polymer so that when it is in the stomach’s acidic pH, hydrogen bonds hold the material together. But these bonds start disappearing in the neutral pH of the intestines when carboxyl groups in the polymer deprotonate, allowing the hydrogel to dissolve. The scientists showed that their design works in pigs.

With the support of the Bill & Melinda Gates Foundation, the team is working to build these polymers into safe drug delivery devices that could reside in the stomach for days or even weeks. Patients could then swallow one pill containing a smart device to dose out medicine rather than daily pills to combat a disease or infection.

Patients not taking medicines at prescribed times or skipping doses are big problems in global healthcare, leading to avoidable complications and antibiotic resistance, Traverso told C&EN. Drug delivery devices using the new polymers could offer a safe solution to the problem of patient compliance, he says.

“The idea is fantastic” says Mehdi Jorfi, who is a biomaterials scientist at MIT and was not involved in the study. “The challenge is can one engineer a smart device that can release different drugs with different release profiles for a variety of applications without tuning the polymer design?”