Multilayer microcapsules enable PET-guided theranostic approach

cancer newspaper
The capsules could be used to carry the anticancer drug doxorubicin. (PDPics/Pixabay)

Researchers have claimed “a major step forward” in the development of radio-labeled, microcapsule drug delivery systems. The microcapsules are designed to address shortcomings of existing delivery systems such as low drug loading capacities.

Adding ligands that bind radionuclides to delivery vehicles enables physicians to detect drug carriers in the human body using positron emission tomography (PET) imaging. The approach could equip physicians to tell if a drug delivery vehicle has reached its target organ and spread throughout the tissue. Advocates of the model see it as a way to make treatment more efficient and cost-effective. 

However, PET-guided theranostics suffer from limitations such as low drug loading capacities and the limited time window in which imaging is possible. Researchers at the University of Alabama at Birmingham set out to address those shortcomings by labeling hollow capsules with zirconium-89.  

In 2017, the researchers showed the microcapsules can contain a cancer drug until they are exposed to ultrasound, potentially enabling the delivery of larger doses of chemotherapy to solid tumors without harming healthy tissues. The latest work, details of which were published in ACS Applied Materials & Interfaces, describes a change to bind zirconium-89 more tightly to the microcapsule.

“We believe this system also provides the groundwork for a universal drug delivery carrier that can be coupled with advanced targeted treatments, such as patient-tailored gene therapeutics, and can lead to the advancement of human health through molecularly targeted, image-guided precision drug delivery,” Eugenia Kharlampieva and Suzanne Lapi, co-senior authors, said in a statement.

With the capsules retaining 17% more zirconium-89 than an alternative design, the researchers were able to monitor the capsules in vivo for seven days. Most of the capsules ended up in the spleen, liver and lungs and the researchers think surface modifications could enhance their targeting ability.