Fluorine-19 MRI is a promising noninvasive diagnostic method. However, the absence of a nontoxic fluorine-19 MRI tracer that does not suffer from poor biodistribution as a result of its strong fluorophilicity is a constant hurdle in the widespread applicability of this otherwise versatile diagnostic technique. The poly[N-(2-hydroxypropyl)methacrylamide]-block-poly[N-(2,2-difluoroethyl)acrylamide] thermoresponsive copolymer was proposed as an alternative fluorine-19 MRI tracer capable of overcoming such shortcomings. In this paper, the internal structure of self-assembled particles of this copolymer was investigated by various methods including 1D and 2D NMR, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS). The elucidated structure appears to be that of a nanogel with greatly swollen hydrophilic chains and tightly packed thermoresponsive chains forming a network within the nanogel particles, which become more hydrophobic with increasing temperature. Its capacity to provide a measurable fluorine-19 NMR signal in its aggregated state at human body temperature was also investigated and confirmed. This capacity stems from the different fluorine-19 nuclei relaxation properties compared to those of hydrogen-1 nuclei.

Department of NMR Spectroscopy Faculty of Science Charles University Hlavova 8 128 43 Prague 2 Czech Republic

Department of Organic Chemistry Faculty of Science Charles University Hlavova 8 128 43 Prague 2 Czech Republic

Department of Physical and Macromolecular Chemistry Faculty of Science Charles University Hlavova 8 128 43 Prague 2 Czech Republic

Institute of Biophysics and Informatics Charles University 1st Faculty of Medicine Salmovská 1 120 00 Prague 2 Czech Republic

Institute of Macromolecular Chemistry Czech Academy of Sciences Heyrovského náměstí 2 162 06 Prague 6 Czech Republic

Institute of Physics Faculty of Mathematics and Physics Charles University Prague Ke Karlovu 3 121 16 Prague 2 Czech Republic

Zobrazit více v PubMed

Hashemi R.H., Bradley W.G., Lisanti C.J. MRI: The Basics. Lippincott Williams & Wilkins; Philadelphia, PA, USA: 2012. DOI

Ruiz-Cabello J., Barnett B.P., Bottomley P.A., Bulte J.W.M. Fluorine (19F) MRS and MRI in Biomedicine. NMR Biomed. 2011;24:114–129. doi: 10.1002/nbm.1570. PubMed DOI PMC

Jirak D., Galisova A., Kolouchova K., Babuka D., Hruby M. Fluorine Polymer Probes for Magnetic Resonance Imaging: Quo Vadis? Magn. Reson. Mater. Phys. Biol. Med. 2019;32:173–185. doi: 10.1007/s10334-018-0724-6. PubMed DOI PMC

Ahrens E.T., Rothbächer U., Jacobs R.E., Fraser S.E. A Model for MRI Contrast Enhancement Using T1 Agents. Proc. Natl. Acad. Sci. USA. 1998;95:8443–8448. doi: 10.1073/pnas.95.15.8443. PubMed DOI PMC

Ahrens E.T., Helfer B.M., O’Hanlon C.F., Schirda C. Clinical Cell Therapy Imaging Using a Perfluorocarbon Tracer and Fluorine-19 MRI. Magn. Reson. Med. 2014;72:1696–1701. doi: 10.1002/mrm.25454. PubMed DOI PMC

Staal X., Koshkina O., Srinivas M. Fluorine in Life Sciences: Pharmaceuticals, Medicinal Diagnostics, and Agrochemicals. Academic Press; Cambridge, MA, USA: 2019. 11-In Vivo 19-Fluorine Magnetic Resonance Imaging; pp. 397–424. DOI

Fox M.S., Gaudet J.M., Foster P.J. Fluorine-19 MRI Contrast Agents for Cell Tracking and Lung Imaging. Magn. Reson. Insights. 2015;8(Suppl. 1):53–67. doi: 10.4137/MRI.S23559. PubMed DOI PMC

Gillis E.P., Eastman K.J., Hill M.D., Donnelly D.J., Meanwell N.A. Applications of Fluorine in Medicinal Chemistry. J. Med. Chem. 2015;58:8315–8359. doi: 10.1021/acs.jmedchem.5b00258. PubMed DOI

van Heeswijk R.B., Pilloud Y., Flögel U., Schwitter J., Stuber M. Fluorine-19 Magnetic Resonance Angiography of the Mouse. PLoS ONE. 2012;7:e42236. doi: 10.1371/annotation/533f969f-0337-4145-906a-565cb11bfa8a. PubMed DOI PMC

Kolouchova K., Sedlacek O., Jirak D., Babuka D., Blahut J., Kotek J., Vit M., Trousil J., Konefał R., Janouskova O., et al. Self-Assembled Thermoresponsive Polymeric Nanogels for 19F MR Imaging. Biomacromolecules. 2018;19:3515–3524. doi: 10.1021/acs.biomac.8b00812. PubMed DOI

Kolouchova K., Jirak D., Groborz O., Sedlacek O., Ziolkowska N., Vit M., Sticova E., Galisova A., Svec P., Trousil J., et al. Implant-Forming Polymeric 19F MRI-Tracer with Tunable Dissolution. J. Control. Release. 2020;327:50–60. doi: 10.1016/j.jconrel.2020.07.026. PubMed DOI

Babuka D., Kolouchova K., Hruby M., Groborz O., Tosner Z., Zhigunov A., Stepanek P. Investigation of the Internal Structure of Thermoresponsive Diblock Poly(2-Methyl-2-Oxazoline)-b-Poly[N-(2,2-Difluoroethyl)Acrylamide] Copolymer Nanoparticles. Eur. Polym. J. 2019;121:109306. doi: 10.1016/j.eurpolymj.2019.109306. DOI

Sedlacek O., Jirak D., Galisova A., Jager E., Laaser J.E., Lodge T.P., Stepanek P., Hruby M. 19F Magnetic Resonance Imaging of Injectable Polymeric Implants with Multiresponsive Behavior. Chem. Mater. 2018;30:4892–4896. doi: 10.1021/acs.chemmater.8b02115. DOI

Murthy S.K. Nanoparticles in Modern Medicine: State of the Art and Future Challenges. Int. J. Nanomed. 2007;2:129–141. PubMed PMC

Zhang L., Gu F.X., Chan J.M., Wang A.Z., Langer R.S., Farokhzad O.C. Nanoparticles in Medicine: Therapeutic Applications and Developments. Clin. Pharmacol. Ther. 2008;83:761–769. doi: 10.1038/sj.clpt.6100400. PubMed DOI

Maeda H., Wu J., Sawa T., Matsumura Y., Hori K. Tumor Vascular Permeability and the EPR Effect in Macromolecular Therapeutics: A Review. J. Control. Release. 2000;65:271–284. doi: 10.1016/S0168-3659(99)00248-5. PubMed DOI

Kim S., Lim Y.T., Soltesz E.G., De Grand A.M., Lee J., Nakayama A., Parker J.A., Mihaljevic T., Laurence R.G., Dor D.M., et al. Near-Infrared Fluorescent Type II Quantum Dots for Sentinel Lymph Node Mapping. Nat. Biotechnol. 2004;22:93–97. doi: 10.1038/nbt920. PubMed DOI PMC

Akerman M.E., Chan W.C.W., Laakkonen P., Bhatia S.N., Ruoslahti E. Nanocrystal Targeting in Vivo. Proc. Natl. Acad. Sci. USA. 2002;99:12617–12621. doi: 10.1073/pnas.152463399. PubMed DOI PMC

Gao X., Cui Y., Levenson R.M., Chung L.W.K., Nie S. In Vivo Cancer Targeting and Imaging with Semiconductor Quantum Dots. Nat. Biotechnol. 2004;22:969–976. doi: 10.1038/nbt994. PubMed DOI

Huh Y.-M., Jun Y., Song H.-T., Kim S., Choi J., Lee J.-H., Yoon S., Kim K., Shin J.-S., Suh J.-S., et al. In Vivo Magnetic Resonance Detection of Cancer by Using Multifunctional Magnetic Nanocrystals. J. Am. Chem. Soc. 2005;127:12387–12391. doi: 10.1021/ja052337c. PubMed DOI

Tiwari G., Tiwari R., Sriwastawa B., Bhati L., Pandey S., Pandey P., Bannerjee S.K. Drug Delivery Systems: An Updated Review. Int. J. Pharm. Investig. 2012;2:2–11. doi: 10.4103/2230-973X.96920. PubMed DOI PMC

Allen T.M., Cullis P.R. Drug Delivery Systems: Entering the Mainstream. Science. 2004;303:1818–1822. doi: 10.1126/science.1095833. PubMed DOI

Duncan R. The Dawning Era of Polymer Therapeutics. Nat. Rev. Drug Discov. 2003;2:347–360. doi: 10.1038/nrd1088. PubMed DOI

De Jaeghere F., Allémann E., Kubel F., Galli B., Cozens R., Doelker E., Gurny R. Oral Bioavailability of a Poorly Water Soluble HIV-1 Protease Inhibitor Incorporated into PH-Sensitive Particles: Effect of the Particle Size and Nutritional State. J. Control. Release. 2000;68:291–298. doi: 10.1016/S0168-3659(00)00272-8. PubMed DOI

Ludwig A. The Use of Mucoadhesive Polymers in Ocular Drug Delivery. Adv. Drug Deliv. Rev. 2005;57:1595–1639. doi: 10.1016/j.addr.2005.07.005. PubMed DOI

Kumar M., Kong X., Behera A.K., Hellermann G.R., Lockey R.F., Mohapatra S.S. Chitosan IFN-Gamma-PDNA Nanoparticle (CIN) Therapy for Allergic Asthma. Genet. Vaccines Ther. 2003;1:3. doi: 10.1186/1479-0556-1-3. PubMed DOI PMC

Popovic N., Brundin P. Therapeutic Potential of Controlled Drug Delivery Systems in Neurodegenerative Diseases. Int. J. Pharm. 2006;314:120–126. doi: 10.1016/j.ijpharm.2005.09.040. PubMed DOI

Schlachetzki F., Zhang Y., Boado R.J., Pardridge W.M. Gene Therapy of the Brain: The Trans-Vascular Approach. Neurology. 2004;62:1275–1281. doi: 10.1212/01.WNL.0000120551.38463.D9. PubMed DOI

Pridgen E.M., Langer R., Farokhzad O.C. Biodegradable, Polymeric Nanoparticle Delivery Systems for Cancer Therapy. Nanomedicine. 2007;2:669–680. doi: 10.2217/17435889.2.5.669. PubMed DOI

Yoo D., Lee J.H., Shin T.H., Cheon J. Theranostic Magnetic Nanoparticles. Acc. Chem. Res. 2011 doi: 10.1021/ar200085c. PubMed DOI

Bamrungsap S., Zhao Z., Chen T., Wang L., Li C., Fu T., Tan W. Nanotechnology in Therapeutics: A Focus on Nanoparticles as a Drug Delivery System. Nanomedicine. 2012;7:1253–1271. doi: 10.2217/nnm.12.87. PubMed DOI

Nakayama M., Okano T. Intelligent Thermoresponsive Polymeric Micelles for Targeted Drug Delivery. J. Drug Deliv. Sci. Technol. 2006;16:35–44. doi: 10.1016/S1773-2247(06)50005-X. DOI

Ghosh S. Recent Research and Development in Synthetic Polymer-Based Drug Delivery Systems. J. Chem. Res. 2004;2004:241–246. doi: 10.3184/0308234041209158. DOI

Knop K., Hoogenboom R., Fischer D., Schubert U.S. Poly(Ethylene Glycol) in Drug Delivery: Pros and Cons as Well as Potential Alternatives. Angew. Chem. Int. Ed. 2010;49:6288–6308. doi: 10.1002/anie.200902672. PubMed DOI

Bauer M., Lautenschlaeger C., Kempe K., Tauhardt L., Schubert U.S., Fischer D. Poly(2-Ethyl-2-Oxazoline) as Alternative for the Stealth Polymer Poly(Ethylene Glycol): Comparison of in Vitro Cytotoxicity and Hemocompatibility. Macromol. Biosci. 2012;12:986–998. doi: 10.1002/mabi.201200017. PubMed DOI

Tucker B.S., Sumerlin B.S. Poly(N-(2-Hydroxypropyl) Methacrylamide)-Based Nanotherapeutics. Polym. Chem. 2014;5:1566–1572. doi: 10.1039/C3PY01279D. DOI

De la Rosa V.R. Poly(2-Oxazoline)s as Materials for Biomedical Applications. J. Mater. Sci. Mater. Med. 2014;25:1211–1225. doi: 10.1007/s10856-013-5034-y. PubMed DOI

Sedláček O., Černoch P., Kučka J., Konefal R., Štěpánek P., Vetrík M., Lodge T.P., Hrubý M. Thermoresponsive Polymers for Nuclear Medicine: Which Polymer Is the Best? Langmuir. 2016;32:6115–6122. doi: 10.1021/acs.langmuir.6b01527. PubMed DOI

Blanazs A., Armes S.P., Ryan A.J. Self-Assembled Block Copolymer Aggregates: From Micelles to Vesicles and Their Biological Applications. Macromol. Rapid Commun. 2009;30:267–277. doi: 10.1002/marc.200800713. PubMed DOI

Jakeš J. Regularized Positive Exponential Sum (REPES) Program-A Way of Inverting Laplace Transform Data Obtained by Dynamic Light Scattering. Collect. Czech. Chem. Commun. 1995;60:1781–1797. doi: 10.1135/cccc19951781. DOI

Štěpánek P. Chapter 4: Data Analysis in Dynamic Light Scattering. In: Brown W., editor. Dynamic Light Scattering. Oxford science publications; Oxford, UK: 1993.

Kieffer J., Karkoulis D. PyFAI, a Versatile Library for Azimuthal Regrouping. J. Phys. Conf. Ser. 2013;425:202012. doi: 10.1088/1742-6596/425/20/202012. DOI

Breßler I., Kohlbrecher J., Thünemann A.F. SASfit: A Tool for Small-Angle Scattering Data Analysis Using a Library of Analytical Expressions. J. Appl. Crystallogr. 2015;48:1587–1598. doi: 10.1107/S1600576715016544. PubMed DOI PMC

Doucet M., Cho J.H., Alina G., Bakker J., Bouwman W., Butler P., Campbell K., Gonzales M., Heenan R., Jackson A., et al. SasView Version 4.2. Zenodo; Berlin, Germany: 2018. DOI

Findeisen M., Brand T., Berger S. A 1H-NMR Thermometer Suitable for Cryoprobes. Magn. Reson. Chem. 2006;45:175–178. doi: 10.1002/mrc.1941. PubMed DOI

Wishart D.S., Bigam C.G., Yao J., Abildgaard F., Dyson H.J., Oldfield E., Markley J.L., Sykes B.D. 1H, 13C and 15N Chemical Shift Referencing in Biomolecular NMR. J. Biomol. NMR. 1995;6:135–140. doi: 10.1007/BF00211777. PubMed DOI

Cano K.E., Smith M.A., Shaka A.J. Adjustable, Broadband, Selective Excitation with Uniform Phase. J. Magn. Reson. 2002;155:131–139. doi: 10.1006/jmre.2002.2506. PubMed DOI

Wang X., Wu C. Light-Scattering Study of Coil-to-Globule Transition of a Poly(N-Isopropylacrylamide) Chain in Deuterated Water. Macromolecules. 1999;32:4299–4301. doi: 10.1021/ma9902450. DOI

Kreuzer L.P., Widmann T., Hohn N., Wang K., Bießmann L., Peis L., Moulin J.-F., Hildebrand V., Laschewsky A., Papadakis C.M., et al. Swelling and Exchange Behavior of Poly(Sulfobetaine)-Based Block Copolymer Thin Films. Macromolecules. 2019;52:3486–3498. doi: 10.1021/acs.macromol.9b00443. DOI

Sun J., Peng Y., Chen Y., Liu Y., Deng J., Lu L., Cai Y. Effect of Molecular Structure on Thermoresponsive Behaviors of Pyrrolidone-Based Water-Soluble Polymers. Macromolecules. 2010;43:4041–4049. doi: 10.1021/ma100133q. DOI

Luo C., Fu W., Li Z., Zhao B. Multi-Responsive Polymethacrylamide Homopolymers Derived from Tertiary Amine-Modified l-Alanine. Polymer. 2016;101:319–327. doi: 10.1016/j.polymer.2016.08.091. DOI

Lodge T.P., Bang J., Hanley K.J., Krocak J., Dahlquist S., Sujan B., Ott J. Origins of Anomalous Micellization in Diblock Copolymer Solutions. Langmuir. 2003;19:2103–2109. doi: 10.1021/la0268808. DOI

Long-term in vivo dissolution of thermo- and pH-responsive, 19F magnetic resonance-traceable and injectable polymer implants