UNC scientists create world’s tiniest organic particles

[Guest guest]

Breakthrough: UNC scientists have created world's tiniest uniform,

precisely shaped organic particles

Chapel Hill, N.C. | June 21, 2005

By DAVID WILLIAMSON

UNC News Services

University of North Carolina at Chapel Hill chemists have developed

what they believe is a breakthrough method of creating the world's

tiniest manufactured particles for delivering drugs and other organic

materials into the human body.

Adapting technology pioneered by the electronics industry in

fabricating transistors, the team has figured out for the first time

how to create particles for carrying genetic material, pharmaceuticals

and other compounds of unprecedented small size and uniformity. The

tiny bits are so small they can be designed and constructed to measure

only a hundred nanometers or so in diameter. A nanometer is a

billionth of a meter.

Leading the group is Dr. ph M. DeSimone, R. Kenan Jr.

Distinguished professor of chemistry and chemical engineering at UNC

and N.C. State University. A member of the UNC College of Arts and

Sciences and the National Academy of Engineering, DeSimone also

directs the National Science Foundation Science and Technology Center

for Environmentally Responsible Solvents and Processes and the

Institute for Advanced Materials, Nanoscience and Technology at UNC.

" Billions of dollars are being spent now on nanotechnology and

nanoparticles, but 99 percent of the materials people are focusing on

are metals and metal oxides, which are inorganic, " DeSimone said. " Our

method, which is really exciting, for the first time opens the world's

door to marrying organic materials to nanotechnology. Biology, after

all, is almost exclusively organic materials.

" We really believe this work will have a profound positive impact down

the road on human health care. This includes, but is not limited to,

chemotherapy, gene therapy, disease detection and drug delivery. "

A report on the findings appeared online this morning (June 21) in the

Journal of the American Chemical Society. Other authors -- all in

chemistry at UNC -- are Drs. P. Rolland and Ginger M. Denison,

recent Ph.D. recipients; Drs. W. Maynor and Larkin E. Euliss,

postdoctoral fellows; and graduate student Ansley E. Exner.

Until now, DeSimone said, most current techniques for particle

formation were incompatible with organic materials. That was because

they involved baking, etching or processing robust metals and such

with solvents that would have destroyed far more fragile organic

matter such as genes or drugs.

The new method avoids harsh treatment but also allows formation of

uniform particles in any shape designers choose – spheres, rods,

cones, trapezoidal solids, etc. -- and essentially any composition, he

said. The relatively simple process, which he and colleagues are

calling Particle Replication in Nonwetting Templates, or PRINT, also

avoids creating films or " scum layers " that would clump particles

together rather than allowing them to be harvested independent of one

another.

" This is in contrast to traditional imprint lithography with silicon,

glass or quartz molds where it is difficult to eliminate this residual

material between objects, " DeSimone said.

Particles injected into the body can be designed to be biodegradable,

he said. Some are made from the same material used to make surgical

sutures. They will incorporate as " cargo " whatever biological material

designers want to get into patients' bloodstreams for more efficient

uptake by cells for diagnostic testing or therapy.

Studies with various organic compounds have been very successful, the

chemist said. New studies with mice have recently begun at the UNC

School of Medicine, which DeSimone joined as professor of pharmacology.

" The process starts off when we make a master template in a clean room

at places like the Triangle National Lithography Center at N.C. State

University, " DeSimone said. " From that we make impressions with what

we call liquid Teflon, and the resulting molds look something like ice

cube trays with tiny cavities in them. After that, we mold the carrier

and fragile functional materials into whatever particles we want and

gently wash them off the molds with buffer solutions into vials or

other containers to concentrate them. Then they can be injected. "

DeSimone, his colleagues, UNC and others have formed a new company,

Liquidia Technologies Inc., with $2.5 million in angel funding and

venture capital to further develop and commercialize the unique new

technology. It is the second company for which DeSimone has been

largely responsible.

The first was MiCell Technologies, which developed his research

showing that it was possible to use carbon dioxide as a solvent in

place of organic solvents, which polluted the environment.

" We are most excited about the commercial implications of Professor

DeSimone's breakthrough with PRINT, " said Dr. Lowry Caudill, chairman

of Liquidia. " We believe that the PRINT process is an extremely

versatile method that offers unparalleled uniformity and precision for

making organic nanoparticles that will have profound implications in

medicine and many other industries, including display technologies.

" Prior to this, no one else has fused the highly uniform and precise

methods for fabricating transistors with the organic nanoparticle

world, " said Bruce Boucher, president of Liquidia. " It is truly a

revolutionary discovery. "

Support for the research came from the Office of Naval Research, the

National Science Foundation and the R. Kenan Jr. Distinguished

Professorship.

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