Researchers Push the Limits of Organic Synthesis

A dendritic molecule is one that grows by branching in several directions from its center core. At each branching point, the molecule branches again into a new generation. These molecules can be used for a broad range of biomedical applications, including gene and drug delivery.

In 1983, Nobel Laureate Pierre-Gilles de Gennes predicted that as these molecules continue branching into new generations, the functional groups on the periphery will get so crowded that their reactivity will decrease.

But now, in a paper published in the Proceedings of the National Academy of Sciences, researchers have shown that the organic synthesis breaks down completely and the reactions stop altogether. These results could improve the efficiency of gene and drug delivery and could also provide a new plan of attack in the rising antimicrobial-resistance problem.

The research was led by Virgil Percec, the P. Roy Vagelos Professor of Chemistry; postdocs Davit Jishkariani, Yam Timsina, Silvia Grama, Srujana Yadavalli, Ralph-Olivier Moussodia and Pawaret Leowanawat; graduate students Syeda Gillani and Masoumeh Divar; and undergraduate student Angely Berrios Camacho. Penn alumnus Christopher MacDermaid provided the computational simulations.

​​​​​​​​​​​​​​“This is a fundamental event for the field of dendrimes, as well as the fields of organic chemistry and iterative synthesis,” Percec says. “When you take these molecules and interact them with nucleic acids, the reactivity becomes zero and they stop reacting. Therefore, you can predict what molecule to make at a smaller generation so that all the groups are going to interact.”

Click here to read the full story.

Arts & Sciences News

Michael C. Horowitz Awarded Department of Defense Grant to Lead Team on Study of Autonomous Systems and AI

Michael C. Horowitz, Professor of Political Science, will oversee the study of autonomous systems and artificial intelligence.

View Article >
Earthquakes at the Nanoscale

In collaboration with Robert Carpick and David Goldsby, Tian, who graduated from Penn in 2017 with a doctorate in physics, recently published a paper in Physical Review Letters which attempts to tackle these devastating natural phenomena by investigating the laws of friction at the smallest possible scale, the nanoscale.

View Article >
Doris Wagner Named Robert I. Williams Term Professor

A leader in the fields of plant biology, chromatin modification, and epigenetics, Wagner’s research focuses on understanding at the molecular level the complex changes that occur when an organism switches developmental programs.

View Article >
Wrongful Convictions Reported for 6 Percent of Crimes

A study from Penn criminologists results in the first general estimate for the prison population as a whole.

View Article >
Race Has a Place in Human Genetics Research, Philosopher Argues

Penn philosopher Quayshawn Spencer says there is a racial classification that’s medically useful to reliably sample human genetic diversity.

View Article >
Exploring the Sounds of the Middle Ages

Assistant Professor of Music Mary Channen Caldwell's freshman seminar course, “Hearing (in) the Middle Ages,” explores a range of sounds heard throughout the medieval period, whether produced by people, instruments, bells, or animals.

View Article >