Scanning electron micrograph of BCNU-loaded microspheres (black and white background) with 3d rendered images of brain cancers cells (yellow) and released BCNU (purple) . Image: Mohammad Reza Abidian Lab
Chemotherapy is a powerful tool in the hands of oncologists, but suffers from poor targeting and leads to patients absorbing considerably more poison than is needed to attack their cancers. Brain tumors in particular are hard to treat with chemo because the blood-brain barrier is very choosy about what it lets through, so even higher doses have to be used. Moreover, opening the cranium and applying patches coated with a drug onto a tumor is not as effective as hoped because of the short half-life of carmustine, or BCNU (bis-chloroethylnitrosourea), a commonly used chemo agent. There’s no method that currently exists that allows for timed release of the drug in a localized fashion, so the only option is repeated opening of the skull in a lot of cases.
Perfect microspheres produced using 4 percent by weight of the polymer. Image: Mohammad Reza Abidian Lab
One alternative approach that’s being investigated is using biodegradable polymers to encapsulate chemo drugs and deliver them in a more targeted fashion to the site of a tumor. Researchers at Penn State have developed a way to produce biodegradable polymer microcapsules that are all of uniform size and shape, and can be injected directly into the brain to degrade as pre-planned by a physician for most effectiveness.
Some details from Penn State:
[Mohammad Reza Abidian, assistant professor of bioengineering, chemical engineering and materials science and engineering] , working with Pouria Fattahi, graduate student in bioengineering and chemical engineering, and Ali Borhan, professor of chemical engineering, looked at using an electrojetting technique to encapsulate BCNU in poly(lactic-co-glycolic) acid, an FDA-approved biodegradable polymer. In electrojetting, a solution containing the polymer, drug and a solvent are rapidly ejected through a tiny nozzle with the system under a voltage as high as 20 kilovolts but with only microamperage. The solvent in the liquid quickly evaporates leaving behind anything from a perfect sphere to a fiber.
“Electrojetting is a low cost, versatile approach,” said Abidian. “We can produce drug-loaded micro/nano-spheres and fibers with same size, high drug-loading capacity and high drug-encapsulation efficiency.”
The researchers tested solutions of polymer from 1 percent by weight to 10 percent by weight and found that at 1 to 2 percent they obtained flattened microspheres, at 3 to 4 percent they had microspheres, at 4 to 6 percent they had microspheres and microfibers, at 7 to 8 percent they had beaded microfibers and above 8 percent they obtained only fibers.
Advanced Materials study: Microencapsulation: Microencapsulation of Chemotherapeutics into Monodisperse and Tunable Biodegradable Polymers via Electrified Liquid Jets: Control of Size, Shape, and Drug Release
Penn State: Microencapsulation produces uniform drug release vehicle
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