Development of silica nanoparticles for 1 H MRI and Optical Imaging - PowerPoint PPT Presentation

Development of silica nanoparticles for 1 H MRI and Optical Imaging Indiana Ternad 1, *, Sarah Garifo 1, *, Dimitri Stanicki, Sébastien Boutry 2 , Lionel Larbanoix 2 , R.N Muller 1,2 , Sophie Laurent 1,2* 1 Department of General, Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons (UMONS), 7000 Mons, Belgium 2 Center for Microscopy and Molecular Imaging (CMMI), 6041 Gosselies, Belgium Corresponding author: indiana.ternad@umons.ac.be; sarah.garifo@student.umons.ac.be; • sophie.laurent@umons.ac.be 1

Development of silica nanoparticles for 1 H MRI and Optical Imaging Graphical Abstract 2

Among the numerous imaging techniques, magnetic resonance imaging (MRI) has become the most powerful tool for diagnosis owing to its high spatial resolution, unlimited tissue penetration, and nonionizing nature. Nevertheless, one can mention its lack of sensitivity, which constitutes a major drawback especially in the field of molecular imaging. The combination of MRI and optical imaging (OI), detecting the luminescence emitted by a tracer, offers the high spatial resolution of the former and the high sensitivity of the latter. In this context, this study focused on the improvement of the relaxation properties of a commercial gadolinium chelate, Gd-HP-DO3A, by a non-covalent confinement of the complex in a semi-permeable nanosystem. To induce the bimodality, a fluorescent compound, i.e. ZW800-1, has been co-encapsulated inside the nanoparticle in a one-pot process. Thanks to their exceptional properties (i.e. biocompatibility, chemical stability, low toxicity) silica nanoparticles (SiO 2 NPs) have been chosen as a matrix. Narrow size distribution SiO 2 NPs were obtained by a reverse microemulsion process (D H : 80 nm). Relaxometric measurements of the synthesized nanoplatforms have proven its efficiency to decrease T 1,2 of water proton molecules. The fluorescent properties were kept after the encapsulation of the fluorophore. The final system was characterized by Dynamic Light Scattering (DLS), Nuclear Magnetic Resonance (NMR) spectroscopy, relaxometry measurements, UV-Vis and IR spectroscopies and Transmission electron microscopy (TEM). Keywords: Nanoparticles ; Silica nanoparticles; Contrast agents ; MRI ; OI; Diagnosis. 3

Introduction Improvement by using paramagnetic Gd complexes. Drawback : Low sensitivity of MRI à à Enhancement of longitudinal water Innersphere mechanism relaxation by τ $ increases Ligand 𝛖 𝐒 Increasing of the MW à τ $ increases With : τ $ : rotational correlation time à MW modification by different structures τ % ∶ residence time of water molecules in the inner sphere q : hydration number ( dendrimer, nanoparticles, …) 4

Introduction Previous researches 1 : Gd-complexes covalently bonded to pegylated silica nanoparticles (SiO 2 NPs) Enhancement r 1 in high field r 1 : 432% (20 MHz) 1. O - O PEG chain O - O (stability) O - O O Paramagnetic 2. O - O complexe - O Samples 𝛖 𝐒 [ns] Full saturation of the nanoparticle surface à Grafting of biovectors on the surface Gd-DTPA-NH 2 0.09 [SiO 2 ]-NH-Gd-DTPA 0.35 1 E. Lipani et al., Langmuir, 29, 3419-3427, 2013. 5

Aim of the project Target platform : Silica nanoparticles (biocompatibility, chemical stability, low toxicity) Possibility of contrasts agents incorporation in the core during the synthesis Synthesis of O O fluorescent/paramagnetic O - O - N N Gd 3+ O - N N OH SiO 2 core O 1. Paramagnetic complexes inside the SiO 2 matrix PEG chains 2. Surface modification by (Stability, post function.) PEGylation 3. (PDI : 1,03) Fluorophore [SiO 2 {Gd-HP-D03A ; ZW800}]-PEG Characterization of the target platform 100 nm 6 6

Results and discussion Target platform : Bimodal SiO 2 NPs for MRI and OI application Reverse microemulsion MRI § Gd-HP-DO3A = O O Co-encapsulation ü Resolutio n O - O - N N cv 3+ Gd O - N N OH O OI [SiO 2 {Gd-HP-D03A;ZW800}] § ZW800 = Improvement of the relaxation • O ü Sensitivity process by a non-covalent O ü High quantum yield O 3 S SO 3 confinement of Gd-complexes in a cv ü Therapeutic window O semi-permeable nanosystem λ excitation: 772 nm N N Co-encapsulation of a fluorophore • λ emission: 788 nm and a paramagnetic agent à N N bimodality application 7 7

Results and discussion Synthetic route: Water in oil microemulsion (reverse microemulsion) O O O Si O Aqueous solution Organic phase: Surfactants: TEOS Cyclohexane 1-hexanol, NH 4 OH Triton X-100 r.t. Aqueous solution [SiO 2 {Gd-HP-DO3A}] Hydrophilic head Hydrophobic end Gd-HP-DO3A ZW800 Room conditions: • 1. Encapsulation of hydrosoluble molecules 2. Surface modification 8 8

Results and discussion Optimization of the coating : surface modification by PEGylation R 1 O O + Si O n R 1 O O R 1 SiO 2 -PEG § Precipitation of the NPs: Coating agent: Acetone Full saturation with biocompatible Si-PEG chains : § Purification steps: Si-PEG 11 : 591-719 g/mol. • Washing with EtOH through several cycles of centrifugation Si-PEG 44 : 2175 g/mol.) • § Redisperion in H 2 O, sonication 9 9

Results and discussion Size charaterization: Photon Correlation Spectroscopy Transmission Electron Microscopy Intensity (%) (PDI : 1,03) 100 nm Spherical morphology 8 3 5 Hydrodynamic diameter (nm) 7 Particules (%) 1 2 3 0 6 1 0 2 5 5 After PEGylation: 8 2 0 4 6 1 5 3 4 1 0 2 5 2 1 Narrow size distributions • 0 0 0 35 40 45 50 21 26 31 36 41 13 15 17 19 21 23 25 27 29 [SiO 2 ]-PEG 44 : [SiO 2 ]-PEG 11 : [SiO 2 ]: Stable NPs in aqueous media • 42,04 ± 4,44 nm 34,31 ± 3,98 nm 20,93 ± 2,17 nm 10 10

Results and discussion Magnetic propreties : stability, relaxivity characterization Samples 20 MHz 60 MHz [s -1 mM -1 ] [s -1 mM -1 ] r 1 (37°C) r 1 (37°C) Gd-HP-DO3A 3.7 2.9 [SiO 2 {Gd-HP-DO3A}] 18.3 24.7 à r 1 increases Enhancement of r 1 at clinical fields Nonporous [SiO 2 {Gd-HP-DO3A}] § r 1 : 494% (20 MHz) Gd-HP-DO3A § Increasing of the MW à slow rotation 11 11

Results and discussion Preliminary in vitro imaging : MR MRI (1T): T 1 [Gd 3+ ] : 0,14 mM 0,07 mM 0,03 mM 0,02 mM 0,01 mM H 2 O [Gd 3+ ] T 2 T 2 [Gd 3+ ] : 0,14 mM 0,07 mM 0,03 mM 0,02 mM 0,01 mM H 2 O OI by FLI LI: [SiO 2 {Gd-HP-D03A;ZW800}]-PEG [ZW800-1] 0,012 mM dil. 2 dil. 4 dil. 6 dil. 10 H 2 O λ Excitation: 737 nm λ Emission: 797 nm 12 12

Conclusions Synthesis of Surface modification by fluorescent/paramagnetic In vitro imaging PEGylation SiO 2 core Ø Synthesis by water in oil Ø Surface modification by Ø Efficient relaxation process microemulsion silanol-PEG chains to Ø Co-encapsulation of a ensure the stability fluorophore (ZW800) and a pramagnetic agent (Gd- HP-DO3A). 13 13

Perspectives hv- chemistry : CF 3 O O OH HO 365 nm O O + OH O ACN:H 2 O COOH HO O O HO O OH HO HO O O OH O HO SiO 2 -PEG 44 UV-sensitive linker SiO 2 -PEG 44 -linker Introduction of the linkers on the top of the coating agent à Less sterically hindered of –COOH functions MRI/ linker vector OI à Possibility of grafting biovectors on the surface Post -derivatisable plateform for MRI and OI 14 14

Acknowledgments (COST CA 15209) 15 15