NEWS OF THE WEEK

SHAPING PARTICLES THE EASY WAY

PARTICLE ENGINEERING: Simple method deforms polymeric spheres

into varied shapes and sizes

WHETHER IT'S ROUND, wrinkled, or rectan­gular, a polymeric particle's shape can strong­ly influence its properties. But there's been no

simple way to control these shapes, until now. Researchers at the University of California, Santa Bar­

bara, have developed a versatile and inexpensive method for making substantial quantities of polymeric particles in more than 20 shapes and sizes (Proc. Natl. Acad. Sci. USA, DOI: io.i073/pnas.0705326i04). The advance could impact applications in drug delivery and personal care, where polymeric particles are important tools.

"Shape affects nearly every function of particles," says Samir Mitragotri, who spearheaded the project with Julie A. Champion and Yogesh K. Katare. "For example, in drug delivery, polymeric particles are used to encap­sulate drugs and release them over prolonged periods of time or target them to specific tissues. Shape influences how drug-carrying particles circulate in blood and ad­here to their target, how particles are cleared by the im­

mune system, and the rate of drug release." To make the shapely particles, the re­

searchers suspend spherical micro- or nanoscale polystyrene beads in polyvinyl al­cohol (PVA) and cast the solution into films. Then, using solvent or heat, they liquefy the particles and stretch the films in either one or two dimensions, deforming the spheres into various shapes depending upon how the films are stretched.

Alternatively, the team stretches the polymer particle-PVA film to create voids around each sphere and then liquefies the particles so they fill the empty spaces. After resolidifying the polystyrene, the research­ers dissolve the surrounding PVA and collect the particles.

"Our method is not only versatile in terms of the shapes that it can produce, but it is also easy to use and employs routine laboratory-methods and equipment," Mitragotri says.

"This is very exciting work based on a powerful concept," comments University of Michigan engineering professor Joerg Lahann. He adds that the technique's im­pressive control of shape and size is likely to be useful for a range of applications, particularly in drug delivery and personal care.—BETHANY HALFORD

FINE FORM Polymeric particles can be made into a variety of shapes, thanks to a new technique (scale bar = 2 μιη).

CHINA EXECUTES DRUG OFFICIAL

SAFETY: Former agency head was sentenced to death for corruption

H IS APPEAL TO the Supreme People's Court rejected, Zheng Xiaoyu, former director of China's State Food & Drug Administration, was

executed on July 10 for taking bribes. A few days earlier, a court in Beijing handed a suspended death sentence to Cao Wenzhuang, another former SFDA official re­sponsible for drug registrations who was also found guilty of accepting bribes.

Zheng was sentenced to death by a lower court on May 29. In his appeal, Zheng argued that he had con­fessed and that a death penalty would be too severe. During the investigation, Zheng implicated other of­ficials and turned over some of the $850,000 in bribe money he had received.

The court acknowledged Zheng's cooperation but ruled that his sentence was appropriate given that he had "endangered public life and health and has had a very negative social impact." Zheng is the most senior official to be executed since 2004.

China's official media reported extensively on the case but did not specify how the sentence was carried out. In China, convicts sentenced to death are usually executed with a bullet to the head or by lethal injection.

SFDA was created in 1998, and Zheng was its first director. He left his post in June 2005 and was arrested last December. According to g China's state media, Zheng approved six | drugs that were later found to be defective, ζ One inj ectable antibiotic approved during ο Zheng's tenure caused the death of at least 1 six patients and injured 80 others, accord- £ ing to www.gov.cn, the main website of the £ Chinese government. £

Shortly before Zheng's execution, on f July 6, Cao was found guilty of accepting $315,000 in bribes for approving the drugs and medical instruments of two compa­nies. His death sentence will likely be commuted to life in prison. Other senior SFDA officials have received long prison sentences in the past few months.

It's not clear whether the companies that made the bribes, which remain unnamed, will also be charged.

At a press conference on the day Zheng was executed, SFDA officials said their agency's reputation has been severely harmed by all these scandals. But a spokeswom­an said the agency has a plan to improve China's food and drug safety by 2010.—JEAN-FRANÇOIS TREMBLAY

Zheng, the former head of China's State Food & Drug Administration, was executed on July 10 for taking bribes.

WWW.CEN-0NLINE.ORG Q JULY 16, 2007