EXAFS can be successfully applied to resolve local atomic structures of very low symmetry. We used this technique to get a better insight into the local environment of iron atoms in di-alanino acid derivative of protoporphyrin IX. Right now, these compounds undergo intensive clinical tests as potential photosensitizing candidates for photodiagnosis and photodynamic therapy (PDT). In PDT, the controlled photosensitization of reactive oxygen species (ROS), including singlet oxygen (¹∆_g), is believed to be responsible for triggering a cascade of subsequent biochemical processes resulting in eradication of tumor cells. In particular, di-amino acid derivatives of protoporphyrin IX attract a lot of attention since they reveal selective retention by malignant tissues and are also eficient ROS generators. Our preliminary electron spin resonance (ESR) study revealed the presence of high-spin, trivalent iron atoms (FeIII, S=5/2) in di-alanino acid derivative of protoporphyrin IX nominally iron-free compound. EXAFS measurements were performed at station BM26A at ESRF. The analysis of EXAFS spectra of Fe-K absorption edge indicated iron presence inside the protoporphyrin IX ring and revealed the bromine atom as one of the first neighbors. The comparison of the shift of Fe-K absorption edge for di-alanino acid derivative of protoporphyrin IX and the material of reference, Fe2O3, confirm the presence of the trivalent iron centers in this novel photosensitizer.

Most probably the location of iron and bromine depends on technological process of preparation the samples. Consequence of precise determination of place of bonding the heavy atoms will be finding the most efficient and no expensive purification procedure to obtain iron and bromine free photosensitizer and allowance to concentrate on most effective technology production process.

Acknowledgments :

This work was partially supported by grant N202 053 32/1197

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/11806 must be provided.

1. Location of metals in ZnO electrospined nanofibers
2. Can we control the process of room temperature ferromagnetic clusters formation in GaMnAs matrix?
3. Optimization of technology for contact metallization in electronic devices - XRD and EXAFS studies
4. Raman spectroscopy and magnetic properties of bulk Zn₀₉₈₄Co_0.016O crystal
5. Phase composition study of natural minerals used as a source of white pigment production
6. Electronic structure of Mn atoms in (Ga,Mn)As layers modified by high temperature annealing
7. Identification of Mg based phases in ilmenites by X-ray absorption spectroscopy
8. Influence of high temperature annealing on the local atomic structure around Mn atoms and magnetic properties of (Ga,Mn)As layers
9. Method of Manganese co-doping of LT ZnO films
10. The single particles approach of x-ray miroanalysis for estimation a phase composition of altered ilmenite used in pigments production
11. Crystalline structure and surface morphology of Dy_xO_y films grown on Si
12. Analysis of stress in buried Ge layers by means of X-ray fluorescence
13. X-ray fluorescence detection of iron in diaminoacid derivatives of protoporhyrin IX.
14. Total electron yield X- ray absorption applied for hard materials studies
15. CBN-Ti/TiN composites: hardness and chemical equilibrium as function of temperature
16. Use of element selective methods for characterization of thin films
17. Synchrotron Radiation - Sources and Properties
18. Investigation of Ge quantum dots buried in silicon matrix by x-ray absorption
19. Characterization of the c- BN/ TiC, Ti3SiC2, TiN systems by element selective spectroscopy
20. Application of Electron Paramagnetic Spectroscopy to Study Protein Folding/Unfolding: from Rapid Mixing Stopped-Flow to High-Hydrostatic Pressure EPR