Iron Oxide Nanoparticle-Based
Magnetic Resonance Method
to Monitor Release Kinetics from Polymeric Particles with High Resolution
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Abstract
A new method to precisely monitor rapid release kinetics
from polymeric
particles using super paramagnetic iron oxide nanoparticles, specifically
by measuring spin–spin relaxation time (<i>T</i><sub>2</sub>), is reported. Previously, we have published the formulation
of logic gate particles from an acid-sensitive poly-β-aminoester
ketal-2 polymer. Here, a series of poly-β-aminoester ketal-2
polymers with varying hydrophobicities were synthesized and used to
formulate particles. We attempted to measure fluorescence of released
Nile red to determine whether the structural adjustments could finely
tune the release kinetics in the range of minutes to hours; however,
this standard technique did not differentiate each release rate of
our series. Thus, a new method based on encapsulation of iron oxide
nanoparticles was developed, which enabled us to resolve the release
kinetics of our particles. Moreover, the kinetics matched the relative
hydrophobicity order determined by octanol–water partition
coefficients. To the best of our knowledge, this method provides the
highest resolution of release kinetics to date