"Once the Gd(III) content in the SLN is known, it is possible
to evaluate the longitudinal relaxivity of these systems
from the observed longitudinal water proton relaxation rate.
In regard to this, it has been necessary to assess the diamagnetic
contribution to the water relaxation rate in the presence
of the SLN. For this reason, we first prepared SLN
without adding the paramagnetic chelates and then we measured
the dependence of the water proton relaxation rate
(Rld) versus the SLN concentration. The interaction between
solvent water molecules and the solid nanoparticles, and the
consequent decrease of their molecular tumbling, results in
an increase of the observed relaxation rate. The correlation
between Rld and the SLN content was linear in the SLN
concentration range used in this work (0–200 mg/ml).
The diamagnetic contribution is, thus, computable, at a
given SLN concentration, from the slope of the resulting
straight line. Interestingly, the diamagnetic contribution is
not affected by the type of the microemulsion used in the
SLN preparation."

Большое спасибо!

Взаимодействие молекул воды, являющейся растворителем, с твердыми
наночастицами приводит к снижению их подвижности и, соответственно, - к повышению времени (спин-решеточной) релаксации.