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.
Graphical abstract
Similar content being viewed by others
References
Abyaneh S, Hoda MR, Vakili FZ, Choi P, Lavasanifar A (2015) Rational design of block copolymer micelles to control burst drug release at a nanoscale dimension. Acta Biomater 24:127–139
Ahmed GA, Khalil SK, Abbas L, Sherif HH, Abdel-Rahman EA, Saber SH, Hassan M, Hassan MH (2020) ATR-IR and EPR spectroscopy for detecting the alterations in cortical synaptosomes induced by aluminium stress. Spectrochimica Acta Part A Mol Biomol Spectrosc 228:117535
Aliabadi HM, Mahmud A, Sharifabadi AD, Lavasanifar A (2005) Micelles of methoxy poly(ethylene oxide)-b-poly(epsilon-caprolactone) as vehicles for the solubilization and controlled delivery of cyclosporine A. J Control Release 104:301–311
Alonso L, Menegatti R, Gomes RS, Dorta ML, Luzin RM, Lião LM, Alonso A (2020) Antileishmanial activity of the chalcone derivative LQFM064 associated with reduced fluidity in the parasite membrane as assessed by EPR spectroscopy. Eur J Pharm Sci 151:105407
Audran G, Bosco L, Nkolo P, Bikanga R, Brémond P, Butscher T, Marque SRA (2016) ’The β-phosphorus hyperfine coupling constant in nitroxides: 6. Solvent effects in non-cyclic nitroxides. Organ. Biomol. Chem. 14:3729–3743
Bales BL, Messina L, Vidal A, Peric M, Nascimento OR (1998) Precision relative aggregation number determinations of sds micelles using a spin probe. A model of micelle surface hydration. J Phys Chem B 102:10347–10358
Bhadran A, Shah T, GK Babanyinah, H Polara, S Taslimy, MC Biewer, MC Stefan (2023) Recent advances in polycaprolactones for anticancer drug delivery. Pharmaceutics 15
Etienne E, Pierro A, Tamburrini KC, Bonucci A, Mileo E, Martinho M, Belle V (2023) Guidelines for the simulations of nitroxide X-band cw EPR spectra from site-directed spin labeling experiments using simlabel. Molecules 28:1348
Gabbita SP, Butterfield DA, Hensley K, Shaw W, Carney JM (1997) Aging and caloric restriction affect mitochondrial respiration and lipid membrane status: an electron paramagnetic resonance investigation. Free Radic Biol Med 23:191–201
Garg SM, Vakili MR, Lavasanifar A (2015) Polymeric micelles based on poly(ethylene oxide) and α-carbon substituted poly(ɛ-caprolactone): an in vitro study on the effect of core forming block on polymeric micellar stability, biocompatibility, and immunogenicity. Colloids Surf B Biointerfaces 132:161–170
Hemminga MA (1983) Interpretation of ESR and saturation transfer ESR spectra of spin labeled lipids and membranes. Chem Phys Lipid 32:323–383
Lamch Ł, Gancarz R, Tsirigotis-Maniecka M, Moszyńska IM, Ciejka J, Wilk KA (2021) Studying the “rigid–flexible” properties of polymeric micelle core-forming segments with a hydrophobic phthalocyanine probe using NMR and UV spectroscopy. Langmuir 37:4316–4330
Lebedeva N, Bales BL (2006) Location of spectroscopic probes in self-aggregating assemblies. I. The case for 5-doxylstearic acid methyl ester serving as a benchmark spectroscopic probe to study micelles. J Phys Chem B 110:9791–9799
Mahmud A, Xiong X-B, Lavasanifar A (2006) Novel self-associating poly(ethylene oxide)-block-poly(ε-caprolactone) block copolymers with functional side groups on the polyester block for drug delivery. Macromolecules 39:9419–9428
Man D, Olchawa R (2017) Dynamics of surface of lipid membranes: theoretical considerations and the ESR experiment. Eur Biophys J 46:325–334
Man D, Słota R, Broda MA, Mele G, Li J (2011) Metalloporphyrin intercalation in liposome membranes: ESR study. J Biol Inorg Chem 16:173–181
Markarian SA, Harutyunyan LR, Harutyunyan RS (2005) The properties of mixtures of sodium dodecylsulfate and diethylsulfoxide in water. J Solution Chem 34:361–368
Pitt CG, Song XC, Sik E, Chignell CF (1991) Spin labels as a probe of the molecular environment of covalently bound ligands in an hydrophobic and an hydrophilic polymer. Biomaterials 12:715–721
Sebők-Nagy K, Kóta Z, Kincses A, Fazekas ÁF, Dér A, László Z, Páli T (2023) Spin-label electron paramagnetic resonance spectroscopy reveals effects of wastewater filter membrane coated with titanium dioxide nanoparticles on bovine serum albumin. Molecules 28:6750
Starigazdová J, Nešporová K, Čepa M, Šínová R, Šmejkalová D, Huerta-Angeles G, Velebný V (2020) In vitro investigation of hyaluronan-based polymeric micelles for drug delivery into the skin: the internalization pathway. Eur J Pharm Sci 143:105168
Stoll S, Schweiger A (2006) EasySpin, a comprehensive software package for spectral simulation and analysis in EPR. J Magn Reson 178:42–55
Widder K, MacEwan SR, Garanger E, Núñez V, Lecommandoux S, Chilkoti A, Hinderberger D (2017) Characterisation of hydration and nanophase separation during the temperature response in hydrophobic/hydrophilic elastin-like polypeptide (ELP) diblock copolymers. Soft Matter 13:1816–1822
Xiong X-B, Mahmud A, Uludağ H, Lavasanifar A (2008) Multifunctional polymeric micelles for enhanced intracellular delivery of doxorubicin to metastatic cancer cells. Pharm Res 25:2555–2566
Xiong XB, Falamarzian A, Garg SM, Lavasanifar A (2011) Engineering of amphiphilic block copolymers for polymeric micellar drug and gene delivery. J Control Release 155:248–261
Yonar D, Kılıç Süloğlu A, Selmanoğlu G, Sünnetçioğlu MM (2019) An Electron paramagnetic resonance (EPR) spin labeling study in HT-29 Colon adenocarcinoma cells after Hypericin-mediated photodynamic therapy. BMC Mol Cell Biol. 20:16
Acknowledgements
The authors gratefully acknowledge the support of Applied Pharmaceutical Innovation (support for LT).
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Tonoyan, L., Munira, S., Lavasanifar, A. et al. Application of electron paramagnetic resonance spectroscopy for determining the relative nanoenvironment fluidity of polymeric micelles. Eur Biophys J (2024). https://doi.org/10.1007/s00249-024-01706-y
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00249-024-01706-y