ADVERTISEMENT
2 /3 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Materials

Ultrasensitive Nanoprobes Illuminate pH Levels

Self-assembled structures show glowing response to changes in acidity

by Matt Davenport
July 28, 2014 | APPEARED IN VOLUME 92, ISSUE 30

[+]Enlarge
Credit: J. Am. Chem. Soc.
Each row shows a unique nanoprobe in 11 different buffer solutions. The probes fluoresce only below their target pH, staying dark in more basic conditions.
09230-scicon-phprobes.jpg
Credit: J. Am. Chem. Soc.
Each row shows a unique nanoprobe in 11 different buffer solutions. The probes fluoresce only below their target pH, staying dark in more basic conditions.

Subtle shifts in pH can signal drastic biological changes. Cancer cells, for instance, acidify their surroundings to metastasize more effectively. Although engineered nanoparticles can scout for such conditions nearly anywhere inside an organism, most probes lack the sensitivity to reliably indicate problematic pH levels. Researchers at the University of Texas Southwestern Medical Center have now developed a library of fluorescent nanoprobes that perform across the complete physiological pH range, from 4.0 to 7.4, with exceptional sensitivity to changes in pH as small as 0.3 units (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja5053158). Led by Jinming Gao, the team conjugated block copolymers with fluorophores and fluorescent quenchers. The polymers form micelles in basic conditions, corralling the fluorescent dyes and quenchers into self-­assembled, optically silent nanoparticles. But at lower pH, the micelles fall apart and the dyes are free to fluoresce. By selectively altering the hydrophobicity of certain monomer pairs within the copolymer composition, researchers fine-tuned a probe’s on/off pH. Gao says biocompatibility tests are ongoing in his lab, but preliminary studies have shown that the probes are safe for cancer imaging and tumor resectioning in mice.

X

Article:

This article has been sent to the following recipient:

Leave A Comment

*Required to comment