NEWS OF THE WEEK AIR
POLLUTION
EPA ANALYSIS CALLED FAULTY Congressional researchers say agency's methods skewed toward Bush emission plan
Ε
PAS RECENT ANALYSIS OF
legislation to cut utilities' air pollution is improperly tilted in favor of President George W . Bush's Clear Skies initiative, accord-
POLYMER
A
^SV^fe
Br
120-160
0
Q
' N + Cr
|
I
— N—
8
C&EN
/
DECEMBER
CHEMISTRY
BIOCOMPATIBLE POLYMER VESICLES
DIBLOCK Copolymer consists of pH-sensitive methacrylate block (right) and block with biomimetic phosphorylcholine motif (left).
"0 — P = 0
ing to the nonpartisan Congressio nal Research Service (CRS). T h r e e c o m p e t i n g legislative plans in the Senate would trim sulfur dioxide, nitrogen oxide, and mercury emissions from utility smokestacks. Bush's Clear Skies involves the smallest reductions. Legislation sponsored by Sen. Thomas R. Carper (D-DeL) would make deeper cuts than the Bush plan, while a bill by Sen. James M. Jeffords (I-Vt.) proposes the most stringent emission controls. T h e Carper andJeffords bills also would curb carbon dioxide releases.
12,
2005
NEW CLASS OF PH-SENSITIVE
polymer vesicles formed from diblock copolymers could potentially be used as nanosized drue- and protein-deι.
ι Λ
ι
liveryvehicles, according to the researchers in England w h o syn thesized the materi als (J. Am. Chem. Soc., published online Dec. 1, dx.doi.org/10.1021/ ja0565141). "Unlike many lit erature examples o f block copolymer ves icles, our diblock co polymers can be read-
ily synthesized in high yields from commercially available monomers by atom transfer radical polymer ization in methanol at room tem perature without using protecting group chemistry," says University of Sheffield chemistry professor Steven P. Armes. H e carried out the work with Andrew L. Lewis, research & technology director of Biocompatibles, based in Farnham, U.K., and coworkers. The vesicles are composed of an A B diblock copolymer in which the A block is based o n a highly biocompatible zwitterionic mono mer that contains the biomimetic phosphorylcholine motif. T h e Β block is based on a pH-responsive
EPA's analysis was faulty for a number of reasons, CRS says in a Nov. 23 report. One is that the agency assumed that only congres sional passage of legislation would cut utility emissions, the report says. T h i s ignores the effects of two rules EPA issued earlier this year—one to reduce sulfur diox ide and nitrogen oxides, the other to control mercury from power plants ( C & E N , March 21, page 11). Together, the EPA rules offer emission reductions similar to the Clear Skies plan. T h e CRS report took the two EPA rules into account and found that Clear Skies would cost little to implement and would offer small benefits. '"TheJeffords and Carper bills, however, set more stringent standards t h a n the promulgat ed rules," the C R S report says. It finds that the benefits of each o f t h o s e bills far o u t w e i g h the additional costs they would im pose.—CHERYL HOGUE
tertiary amine methacrylate mono mer. T h e copolymer dissolves in aqueous acidic solution and self-as sembles into well-defined vesicles above p H 7. The vesicles dissociate completely below p H 6. "The phosphorylcholine m o tif makes the polymers the most authentic polymeric analogs of conventional liposomes reported to date," Armes notes. T h e t e a m also s h o w e d that the water-soluble anticancer drug doxorubicin can be encapsulated in the vesicles and released slowly over a period of several hours. "This cleverly designed system is readily prepared through the powerful technique of copper-cata lyzed, controlled radical polymer ization," comments Ian Manners, chemistry professor at the Univer sity ofToronto. "The results on the anticancer drug release demon strate proof of concept, and, bear ing in mind the ease of synthesis, the materials look very promising with respect to further develop ment for controlled-release applica tions."—MICHAEL FREEMANTLE
WWW.CEN-0NLINE.ORG
