Synthesis and Photophysical and Photocatalytic Properties of a Highly Fluorinated and Durable Phthalocyanine-Peptide Bioconjugate for Potential Theranostic Applications

Inorg Chem. 2017 Jun 19;56(12):7210-7216. doi: 10.1021/acs.inorgchem.7b00847. Epub 2017 May 25.

Abstract

The functionalized, asymmetric fluoro-fluoroalkyl scaffold F48H7COOHPcZn (3) was used to prepare F48H7COOPcZn-6-amino-hexanoate-CTVALPGGYVRVC (5), a Pep42 peptide bioconjugate envisioned for photodynamic therapy, which can specifically target the GRP78 chaperone protein overexpressed and exclusively localized on some cancer cell surfaces. The analogous F48H7COOHPcCu (4) has also been prepared, and its single-crystal X-ray structure was elucidated. Despite reduced steric hindrance relative to the nonfunctionalized, single-site complexes of the F64Pc scaffold, no aggregation was detected in solution via UV-vis spectroscopy, for either 3, 4, or 5, consistent with the lack of π stacking observed for the crystalline 4. The 6-aminohexanoic acid-Pep42 moiety diminishes the fluorescence efficiency of 5, relative to 3, but for singlet oxygen (1O2) generation, photochemical hydroperoxidation of β-(-)-citronellol using 5 and 3 occurs with comparable substrate turnover efficiency, albeit at a slower initial triplet oxygen uptake for 5. The bioconjugate 5 is durable; it does not decompose under 1O2 photoreaction conditions. These results suggest a synthetic coupling pathway for obtaining diverse biotargeting polypeptide-fluorinated phthalocyanine bioconjugates of potential utility as both fluorescence reporters and photocatalysts and highlight the importance of fluorinated scaffolds for generating chemically resilient, catalytic, theranostic materials.

MeSH terms

  • Catalysis
  • Cell Line, Tumor
  • Crystallography, X-Ray
  • Endoplasmic Reticulum Chaperone BiP
  • Halogenation
  • Humans
  • Indoles / chemistry*
  • Isoindoles
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemical synthesis*
  • Organometallic Compounds / chemistry*
  • Organometallic Compounds / therapeutic use
  • Peptides / chemistry*
  • Photochemical Processes
  • Photochemotherapy*
  • Theranostic Nanomedicine*

Substances

  • Endoplasmic Reticulum Chaperone BiP
  • HSPA5 protein, human
  • Indoles
  • Isoindoles
  • Organometallic Compounds
  • Peptides
  • phthalocyanine