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UAB creates triple-threat cancer-fighting polymer capsules for guided drug delivery

Chemists at the University of Alabama at Birmingham have designed triple-threat cancer-fighting polymer capsules that bring the promise of guided drug delivery closer to preclinical testing.

Infographic depicting guided drug delivery microcapsules developed by UAB researchersThese multilayer capsules show three traits that have been difficult to achieve in a single entity. They have good imaging contrast that allows detection with low-power ultrasound, they can stably and efficiently encapsulate the cancer drug doxorubicin, and both a low- and higher-power dose of ultrasound can trigger the release of that cargo.

These three features create a guided drug delivery system to target solid tumors. Therapeutic efficacy can be further improved through surface modifications to boost targeting capabilities. Diagnostic low-power ultrasound then could visualize the nanocapsules as they concentrated in a tumor, and therapeutic higher-dose ultrasound would release the drug at ground zero, sparing the rest of the body from dose-limiting toxicity.

This precise control of when and where doxorubicin or other cancer drugs are released could offer a noninvasive alternative to cancer surgery or systemic chemotherapy, the UAB researchers report in the journal ACS Nano, which has an impact factor of 13.3.

We envision an entirely different approach to treating solid human tumors of numerous pathologic subtypes, including common metastatic malignancies such as breast, melanoma, colon, prostate and lung, utilizing these capsules as a delivery platform,” said Eugenia Kharlampieva, Ph.D., an associate professor in the Department of Chemistry, UAB College of Arts and Sciences. “These capsules can protect encapsulated therapeutics from degradation or clearance prior to reaching the target and have ultrasound contrast as a means of visualizing the drug release. They can release their encapsulated drug cargo in specific locations via externally applied ultrasound exposure.”

Kharlampieva — who creates her novel “smart” particles while working at the intersection of polymer chemistry, nanotechnology and biomedical science — says there is an urgent, and so far unmet, need for such an easily fabricated, guided drug delivery system.

The UAB researchers, led by Kharlampieva and co-first authors Jun Chen and Sithira Ratnayaka, use alternating layers of biocompatible tannic acid and poly(N-vinylpyrrolidone), or TA/PVPON, to build their microcarriers. The layers are formed around a sacrificial core of solid silica or porous calcium carbonate that is dissolved after the layers are complete.

By varying the number of layers, the molecular weight of PVPON or the ratio of shell thickness to capsule diameter, the researchers were able to alter the physical traits of the capsules and their sensitivity to diagnostic ultrasound, at power levels below the FDA maximum for clinical imaging and diagnosis.


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