"Brain tumors are one of the world's deadliest diseases," said Mohammad Reza Abidian, assistant professor of bioengineering, chemical engineering and materials science and engineering. "Typically doctors resect the tumors, do radiation therapy and then chemotherapy."
This is a scanning electron micrograph of BCNU-loaded microspheres (black and white background) with 3D rendered images of brain cancers cells (yellow) and released BCNU (purple).
Credit: Mohammad Reza Abidian
The majority of chemotherapy is done intravenously, but, because the drugs are very toxic and are not targeted, they have a lot of side effects. Another problem with intravenous drugs is that they go everywhere in the bloodstream and do not easily cross the blood brain barrier so little gets to the target tumors. To counteract this, high doses are necessary.
"We are trying to develop a new method of drug delivery," said Abidian. "Not intravenous delivery, but localized directly into the tumor site."
Current treatment already includes leaving wafers infused with the anti-tumor agent BCNU in the brain after surgery, but when the drugs in these wafers run out, repeating invasive placement is not generally recommended.
"BCNU has a half life in the body of 15 minutes," said Abidian. "The drug needs protection because of the short half life. Encapsulation inside biodegradable polymers can solve that problem."
Encapsulation of BCNU in microspheres has been tried before, but the resulting product did not have uniform size and drug distribution or high drug-encapsulation efficiency. With uniform spheres, manufacturers can design the microcapsules to precisely control the time of drug release by altering polymer composition. The tiny spheres are also injectable through the skull, obviating the need for more surgery.
Abidian, 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. They report their results in the current issue of Advanced Materials.
"Depending on the desired applications, all the shapes are useful except for the beaded fibers," said Abidian. "While fibers are not good for drug delivery, they are good for tissue engineering applications."
The researchers also investigated the sphericality of the spheres.
"We looked at how spherical they were and found they were perfect," said Abidian. They have a height versus width ratio of 1.05 and they have size uniformity. A perfect sphere would have a ratio of 1.
The researchers also looked into how BCNU releases from the microcapsules. Using mathematics, the researchers established a drug diffusion coefficient for the encapsulation system. This helps in designing how much drug to include in each microcapsule and how long the microcapsules will deliver the required dosage.
The researchers note that BCNU is not the only drug that can be encapsulated in polymer beads for drug delivery. Other drugs can be used but would have their own diffusion coefficients and half lifes.
A'ndrea Elyse Messer | EurekAlert!
ADIR Project: Lasers Recover Valuable Materials
21.07.2017 | Fraunhofer-Institut für Lasertechnik ILT
High-tech sensing illuminates concrete stress testing
20.07.2017 | University of Leeds
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
24.07.2017 | Health and Medicine
24.07.2017 | Automotive Engineering
21.07.2017 | Earth Sciences