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- Title
Application of electron paramagnetic resonance spectroscopy for determining the relative nanoenvironment fluidity of polymeric micelles.
- Authors
Tonoyan, Lusine; Munira, Sirazum; Lavasanifar, Afsaneh; Siraki, Arno G.
- Abstract
Polymeric micelles are nanocarriers for drug, protein and gene delivery due to their unique core/shell structure, which encapsulates and protects therapeutic cargos with diverse physicochemical properties. However, information regarding the micellar nanoenvironment's fluidity can provide unique insight into their makeup. In this study, we used electron paramagnetic resonance (EPR) spectroscopy to study free radical spin probe (5-doxylstearate methyl ester, 5-MDS, and 16-doxylstearic acid, 16-DS) behaviour in methoxy-poly(ethylene oxide)-poly(α-benzyl carboxylate-ε-caprolactone) (PEO-PBCL) and methoxy-poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) polymeric micelles. Spin probes provided information about the spectroscopic rotational correlation time (τ, s) and the spectroscopic partition parameter F. We hypothesized that spin probes would partition into the polymeric micelles, and these parameters would be calculated. The results showed that both 5-MDS and 16-DS spectra were modulated in the presence of polymeric micelles. Based on τ values, 5-MDS revealed that PEO-PCL (τ = 3.92 ± 0.26 × 10−8 s) was more fluid than PEO-PBCL (τ = 7.15 ± 0.63 × 10−8 s). The F parameter, however, could not be calculated due to the rotational hindrance of the probe within the micelles. With 16-DS, more probe rotation was observed, and although the F parameter could be calculated, it was not helpful to distinguish the micelles' fluidity. Also, doxorubicin-loading interfered with the spin probes, particularly for 16-DS. However, using simulations, we could distinguish the hydrophilic and hydrophobic components of the 16-DS probe. The findings suggest that EPR spectroscopy is a valuable method for determining core fluidity in polymeric micelles.
- Subjects
ELECTRON paramagnetic resonance spectroscopy; MICELLES; ELECTRON paramagnetic resonance; ETHYLENE oxide
- Publication
European Biophysics Journal, 2024, Vol 53, Issue 4, p171
- ISSN
0175-7571
- Publication type
Article
- DOI
10.1007/s00249-024-01706-y