The PEG-fluorochrome shielding approach for targeted probe design

J Am Chem Soc. 2012 Nov 28;134(47):19338-41. doi: 10.1021/ja309085b. Epub 2012 Nov 14.

Abstract

We provide a new approach for fluorescent probe design termed "PEG-fluorochrome shielding", where PEGylation enhances quantum yields while blocking troublesome interactions between fluorochromes and biomolecules. To demonstrate PEG-fluorochrome shielding, fluorochrome-bearing peptide probes were synthesized, three without PEG and three with a 5 kDa PEG functional group. In vitro, PEG blocked the interactions of fluorochrome-labeled peptide probes with each other (absorption spectra, self-quenching) and reduced nonspecific interactions with cells (by FACS). In vivo, PEG blocked interactions with biomolecules that lead to probe retention (by surface fluorescence). Integrin targeting in vivo was obtained as the differential uptake of an (111)In-labeled, fluorochrome-shielded, integrin-binding RGD probe and a control RAD. Using PEG to block fluorochrome-mediated interactions, rather than synthesizing de novo fluorochromes, can yield new approaches for the design of actively or passively targeted near-infrared fluorescent probes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Fluorescent Dyes* / administration & dosage
  • Fluorescent Dyes* / chemistry
  • Humans
  • Mice
  • Molecular Probes* / administration & dosage
  • Molecular Probes* / chemical synthesis
  • Molecular Structure
  • Peptides* / administration & dosage
  • Peptides* / chemical synthesis
  • Polyethylene Glycols* / administration & dosage
  • Polyethylene Glycols* / chemistry

Substances

  • Fluorescent Dyes
  • Molecular Probes
  • Peptides
  • Polyethylene Glycols