A STUDY OF WATER T₁ AND T₂ NMR RELAXATION TIMES IN HEALTHY AND CANCER AFFECTED HUMAN BLOOD PLASMA DOPED WITH HEMATOPORPHYRIN IX DYE

Abstract

Human blood plasma water protons relaxation times T₁ ^b and T₂ ^b in the protein bound water phase restricted motion state have been determined for the native and hematoporphyrin IX (HMP) doped samples at the temperature of 20 °C and ¹H NMR frequency of 80 Mhz. The samples belong to either healthy and myeloma affected patients. The resulting bound water relaxation times show a clear dependence from a single irrotational correlation time τ_c ^b, related to the relatively slow motion of the proteins present in solution. Noteworthy the values of the τ_c ^b s slow down in presence of the HMP dye and the effect is more marked in the myeloma blood plasma than in the healthy samples. This observation agrees with the measurements done previously with spectrofluorimetric techniques which show a specific interaction, time persistent, between the HMP and the fraction of the lipoproteins in plasma. The rationalization of the experimental data using the homonuclear magnetic dipolar interaction equations of Solomon-Bloembergen enables to point out that one proton of the water molecule is relaxed by two nearby protons, one of which belongs to one of the hydroxyethyl side chains of the HMP linked with a hydrogen bond to the probed water molecule and stable on the NMR timescale.

Keywords:

• Blood plasma
• Water T₁ and T₂ relaxation times
• Healthy and myeloma affected patients
• Hematoporphyrin IX effect

ACKNOWLEDGMENTS

I thank the Director of the CSSMRE, Prof. Giovanni Giacometti, for his interest about this work, Dr. Alberto Tregnaghi for the samples gift, Prof. Giulio Jori of the Biology Department for introducting myself in the PDT field and the Italian C.N.R. for the financial support.