Cells Can Ferry Drugs In Disk-Shaped Packs | Chemical & Engineering News
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Web Date: March 27, 2015

Cells Can Ferry Drugs In Disk-Shaped Packs

Drug Delivery: Simple fabrication method yields drug-loaded microsized disks that stick to human cells
Department: Science & Technology | Collection: Life Sciences
News Channels: Materials SCENE, Nano SCENE, Biological SCENE
Keywords: drug delivery, cell adhesive, microdisk, cell backpack
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Drug Backpack
One side of a 7-µm-wide, 220-nm-thick disk (left) is composed of a cell adhesive (blue) that helps it attach to cell surfaces while the other side is a drug-laden thermoplastic (red). A fluorescence micrograph (right) shows cultured human leukemia cells carrying such microdisks, demonstrating their potential for drug delivery in the body.
Credit: ACS Appl. Mater. Interfaces
Illustration and fluorescence micrograph of human leukemia cells bearing drug-loaded microdisks.
 
Drug Backpack
One side of a 7-µm-wide, 220-nm-thick disk (left) is composed of a cell adhesive (blue) that helps it attach to cell surfaces while the other side is a drug-laden thermoplastic (red). A fluorescence micrograph (right) shows cultured human leukemia cells carrying such microdisks, demonstrating their potential for drug delivery in the body.
Credit: ACS Appl. Mater. Interfaces

Using an easy, inexpensive method, researchers have developed tiny disk-shaped packs that can ride on cells to deliver drugs (ACS Appl. Mater. Interfaces 2015, DOI: 10.1021/acsami.5b00613). Carried by red or white blood cells, the biodegradable particles could slowly release drugs into the bloodstream or directly inside tumors, says Jingjiao Guan, professor of chemical and biomedical engineering at Florida State University.

A body’s own cells are perfect pack mules for drug delivery. Unlike designer nanoparticles made of proteins or polymers, they can circulate in the body for days without being attacked by the immune system. Scientists have tried to make drug-laden backpacks for cells to carry, but they have been complicated to make and attach to cells.

Guan and his colleagues came up with a simple, low-cost method to make their disks. They made a rubber stamp with an array of microsized pillars and deposited four layers of materials on top: a thermoplastic such as poly(lactic-co-glycolic acid) that can be loaded with drugs, a polyelectrolyte that adheres to cells, and two compounds sandwiched in the middle that link the thermoplastic to the polyelectrolyte adhesive.

Pressing the stamp on a glass slide coated with polyvinyl alcohol (PVA) transfers the four-layer disks from the pillars to the PVA, creating an array of 7-µm-wide, 220-nm-thick disks on the slide. The researchers then dissolved the PVA, releasing the disks into solution, and mixed them into a suspension of cultured human leukemia cells.

The electrostatic attraction between the positively charged cell adhesive and the negatively charged cell surface allows the microdisks to stick to the outside of cells. Since red blood cells are also negatively charged, says Guan, the disks should also bind to them. “In principle, we would take cells from a patient, mix them with the [disks], and then inject them back into the patient,” he says.

The researchers tested the drug carriers by loading the thermoplastic with a fluorescent dye and mixing them in a cell culture. The disks slowly disintegrated, releasing 40% of the dye by weight over seven days.

 
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Comments
Paul Kronick (April 2, 2015 12:07 PM)
What happens to the disks when the cells die?

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