"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!
Watching atoms move in hybrid perovskite crystals reveals clues to improving solar cells
22.11.2017 | University of California - San Diego
Fine felted nanotubes: CAU research team develops new composite material made of carbon nanotubes
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
23.11.2017 | Information Technology
23.11.2017 | Physics and Astronomy
23.11.2017 | Life Sciences