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Online Program Overview Session: PW-22

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New Probes | MRI and Multimodal II

Session chair: Ulrich Flögel - Dusseldorf, Germany; Kristina Djanashvili - Delft, The Netherlands
 
Shortcut: PW-22
Date: Friday, 23 March, 2018, 11:30 AM
Room: Banquet Hall | level -1
Session type: Poster Session

Abstract

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# 194

Low-Molecular-Weight Iron Chelates are promising Alternatives to Gadolinium-based Contrast Agents for T1-weighted Contrast-enhanced MR Imaging (#467)

A. Haeckel1, P. Boehm-Sturm2, J. Xie1, R. Hauptmann1, E. Schellenberger1

1 Charité – Universitätsmedizin Berlin, Radiology, Berlin, Berlin, Germany
2 Charité – Universitätsmedizin Berlin, Exp. Neurology, Berlin, Berlin, Germany

Introduction

Gadolinium-based contrast agents (GBCA) used one third of all magnetic resonance imaging (MRI) sessions are currently under investigation due to gadolinium depositions in several organs, especially in bones and brain (1-2). Although the clinical implications are not clear yet, the European Medicines Agency EMA restricted the use of the less stable linear GBCA to few special applications. Therefore we have synthesized low-molecular-weight iron chelates  and compared them with a typical GBCA in dynamic contrast material-enhanced (DCE)-MRI as used in breast tumor screening (3).

Methods

Relaxivity and contrast effects of synthesized iron chelates in blood serum phantoms were measured at magnetic field strengths from 0.94T to 7T. For in vivo studies, a human breast cancer cell line (MDA-231) was implanted in five mice per group. The dynamic contrast effects of the chelates were compared by performing DCE-MRI with intravenous application of Fe-DTPA or Fe-tCDTA on day 1 and in the same tumors with application of Gd-DTPA (gadopentetate dimeglumine, Magnevist) on day 2. Quantitative DCE maps were generated and compared by one-tailed Pearson correlation tests. 

Results/Discussion

Both iron chelates (Fe-CDTA and Fe-DTPA) have shown good contrast effects in blood serum phantoms. Relaxivity in serum was about twofold lower for Fe-CDTA and fivefold lower for Fe-DTPA compared with Magnevist. However, used at moderately higher concentrations, iron chelates caused similar contrast effects at T1-weighted MR imaging in blood, serum, and breast cancer cell xenografts in mice. The volume transfer constant values for Fe-DTPA and Fe-tCDTA in the same tumors correlated well with those observed for Magnevist (Fe-tCDTA Pearson R, 0.99; P = .0003; Fe-DTPA 0.97; P = .003).

Conclusions

These results suggest, that Iron-based contrast agents are promising alternatives for contrast enhancement in T1-weighted MRI imaging and have great potential to contribute to the safety of MR imaging.

Especially for molecular T1-weighted imaging probes iron chelates should be a safer alternative than gadolinium based probes, since these probes have affinity for certain structures and are thus even more likely to cause organ gadolinium depositions.

References

  1. Runge VM. Safety of the gadolinium-based contrast agents for magnetic resonance imaging, focusing in part on their accumulation in the brain and especially the dentate nucleus. Invest Radiol 2016;51(5):273–279. 
  2. Murata N, Gonzalez-Cuyar LF, Murata K, et al. Macrocyclic and other non-group 1 gadolinium contrast agents deposit low levels of gadolinium in brain and bone tissue: preliminary results from 9 patients with normal renal function. Invest Radiol 2016;51(7):447–453. 
  3. Boehm-Sturm P, Haeckel A, Hauptmann R, Mueller S, Kuhl CK, Schellenberger EA. Low-Molecular-Weight Iron Chelates May Be an Alternative to Gadolinium-based Contrast Agents for T1-weighted Contrast-enhanced MR Imaging. Radiology 2017 7:170116. 
T1 contrast effects and DCE-MRI with Fe-chelates in comparison with Gd-DTPA.

A, T2-weighted preinjection images with tumors indicated by dashed circles; B, T1-weighted preinjec- tion images in same position; C, T1-weighted images several minutes after injection in same position; D, Subtraction images of B and C; and E, color-coded Ktrans parametric maps of tumor overlaid on T2-weighted images. 

Keywords: Gadolinium, iron, chelate, toxicology, MRI
# 202

Spectroscopic and photoacoustic characterization of encapsulated iron oxide super-paramagnetic nanoparticles as a new multiplatform contrast agent (#563)

P. Armanetti1, A. Flori2, C. Avigo1, L. Conti3, B. Valtancoli3, D. Petroni1, S. Doumett4, L. Cappiello4, C. Ravagli4, G. Baldi4, A. Bencini3, L. Menichetti1

1 Italian National Research Council (CNR), Institute of clinical physiology (IFC-CNR), Pisa, Italy
2 Fondazione Toscana Gabriele Monasterio, Pisa, Italy
3 Università degli Studi di Firenze, Dipartimento di Chimica “Ugo Schiff”, Sesto Fiorentino, Firenze, Italy
4 Colorobbia Consulting Srl, Sovigliana – Vinci, Italy

Introduction

Nanoparticles (NPs) surface properties, easy manipulation and functionalization strategies allow the design of sophisticated imaging probes for disease detection and diagnosis. Multifunctional NPs, by combining different imaging modalities in a single multi-modal platform, implement a synergistic approach and show great promise in nanomedicine and theranostics. Here, we present the characterization of bio-conjugated near-infrared (NIR) light-absorbing magnetic NPs (NBRfluo), integrating photoacoustic (PA) and magnetic resonance imaging (MRI) in a new multi-platform contrast agent.

Methods

NBRfluo were synthetized as reported [1] and conjugated with Fluoresceine 488-NHS [2]. PA imaging was performed in vitro (polyethylene tubes) and in chicken breast meat using the VevoLAZR system (VisualSonics Inc.) and a 13-24 MHz PA probe (LZ250). MRI relaxivity of the NPs paramagnetic core was determined in 1% agar-gel at 1.5 T (Signa HDxt clinical scanner, GE). Fast Spin Echo sequences and an in-house developed T1 mapping sequence were used for T2 and T1 measurement. In vitro and ex-vivo fluorescence imaging was performed using a PhotonImager RT system (Biospace Lab): the number of photons per minute per unit of surface area (cpm/cm2) and the contrast were calculated for a ROI selected in the injected region, by integration of 726000 events for 4 s, on a 966x750 pixels image.

Results/Discussion

NBRfluo showed narrow size distribution (mean hydrodynamic diameter and polydispersity index = 41.0±0.6 nm and 0.13±0.02, respectively) and stability (ξ potential = –38 mV). We found suitable absorption in the NIR region, with good PA signal generation efficiency and high photo-stability, both in vitro and ex-vivo. Spectra recorded at different concentration showed a signal decrease up to 740 nm and a plateau up to 970 nm (Fig.1). The PA signal was clearly detectable in ex vivo samples (Contrast-to-noise ratio = 41, axial and lateral spatial resolution = 75 and 135 μm, respectively). Good MRI contrast of NBRfluo paramagnetic core was observed: r2 and r1 were = 468.6 mM-1 s-1 and r1 = 10.78 mM-1 s-1 (r2/r1 = 43.5) respectively at 1.5 T, comparable to values previously obtained for other iron oxide negative contrast agents. Optical images of NBRfluo were produced: the NPs were efficiently localized in vitro (PE tubing) and in chicken breast, showing good contrast (Fig.2).

Conclusions

NBRfluo are characterized by simple bio-conjugation strategy, optical and chemical stability, and straightforward manipulation. This enabled the development of a multi-modal probe with magnetic and spectroscopic properties (both optical and PA), suitable for in vitro and ex vivo real-time imaging of relevant biological targets. The obtained results suggest a promising in vivo use of NBRfluo, which is actually under investigation in our lab.

References

[1] G. Baldi et al. Int. J. Nanomedicine, 2014; 9: 3037–3056

[2] Xiang-Long Wu and Wu-Tu Fan. J. Life Sci. Tech. 2013;1(4):210-215.

 

 

Acknowledgement

This project was funded under Tuscany POR FESR 2014-2020 Framework with the project “INSIDE” (CUP ST:3389.30072014.067000001, years 2016-2018). We are also grateful to Fondazione CNR/Regione Toscana “G. Monasterio” for supporting these research activities.

Fig. 1

a) PA spectra of NBRfluo H2O solutions at different concentrations; b) linear fit of NBRfluo PA signal vs concentration; c) PA imaging of NBRfluo injected in polyethylene tubes (the axial view is reported in the inset: green color for the NBRfluo PA signal, yellow color for PA polyethylene); d) PA imaging of NBRfluo injected in chicken breast meat.

Fig. 2
a) 1.5 T MRI Fast Spin Echo acquisitions of NBRfluo at different echo times (upper) and linear regression line for r2 relaxivity determination (lower); b) fluorescence imaging of NBRfluo injected in a chicken breast sample (upper) and in vitro in a polyethylene tube (lower).
Keywords: Magnetic resonance imaging, photoacoustic, nanoparticles, contrast media, multimodal contrast agent, fluorescence
# 195

A new class of paramagnetic contrast agents: synthesis and physicochemical characterizations of a fluorinated paramagnetic contrast agent (#531)

E. Hequet1, C. Henoumont1, R. Muller1, 2, L. Vander Elst1, S. Laurent1, 2

1 UMONS, Chimie générale, organique et biomédicale, Mons, Belgium
2 CMMI, Gosselies, Belgium

Introduction

Medical imaging is a dynamic area of researches whose one of the goal is the elaboration of more efficient contrast agents (CA). Those agents need to be improved to optimize the detection of affected tissues such as cancers or tumours while decreasing the injected quantity of agents. The paramagnetic contrast agents containing fluorine atoms can be used both on proton and fluorine MRI.
This research field is therefore promising thanks to the ability to map the anatomy by 1H MRI and locate exactly the agents by 19F MRI.

Methods

One of the challenges in this domain is to synthesize a molecule containing several chemically equivalent fluorine atoms with short relaxation times to allow the record of 19F MR images in good conditions.
In that aim, we propose to synthesize a CA containing a paramagnetic ion and nine chemically equivalent fluorine atoms by a cycloaddition reaction between two previously synthesized molecules.

Initially, a derivative of DOTAGA macrocyclic ligand has been synthesized through a multistep synthesis during which an azide function was added and a Gd3+ ion complexed.

Then, a nonafluorinated compound containing an alkyne function has been synthesized in order to allow the use of the contrast agent in fluorine MRI.

Finally, these two molecules were combined via a click chemistry reaction.

Results/Discussion

The structure of the fluorinated paramagnetic contrast agent was confirmed by mass spectrometry. It was also characterized by relaxometry which shows an increase of the agent efficiency in comparison with the parent compound Gd-DOTA. Indeed, the recorded NMRD profile of the agent was compared to its corresponding commercial compound, Gd-DOTA and reflects a better efficiency of the fluorinated paramagnetic contrast agent.

A 19F NMR study has also shown a huge broadening of the peak corresponding to the fluorine atoms which results from the effect of the gadolinium ion on the fluorine relaxation times. It has also been confirmed that the synthesized agent shows a significant decrease of the fluorine-19 relaxation times (from about 2 s for the single molecule to about 10 ms for the molecule conjugated to the paramagnetic macrocycle) which is promising for a future use in 19F MRI.

Conclusions

These preliminary characterizations are very promising. It is now essential to perform 19F MRI in vitro and in vivo tests to evaluate the diagnosis potential of the synthesized contrast agent.

Possible perspectives can be envisaged to allow an active targeting of the compound via the grafting of a biovector, or the addition of more chemically equivalent fluorine atoms via a dendrimeric structure, which could be benefit to increase the sensitivity.

Figure 1 : Fluorinated paramagnetic contrast agent
Keywords: Fluorine, MRI, Gadolinium, Contrast agent
# 196

Biocompatible Materials labelled with Microenvironment Responsive MRI Probes for the follow-up of Cell Transplants (#153)

F. Capuana1, S. Padovan2, C. Grange3, V. Catanzaro4, J. C. Cutrin1, M. Stevanovic5, N. Filipovic5, G. Digilio4

1 University of Turin, Department of Molecular Biotechnology and Health Sciences, Turin, Italy
2 CNR, Institute for Biostructures and Bioimages, Turin, Italy
3 University of Turin, Department of Medical Sciences, Turin, Italy
4 Università del Piemonte Orientale "A. Avogadro", Department of Sciences and Technologic Innovation, Alessandria, Italy
5 Serbian Academy of Sciences and Arts, Institute of Technical Sciences, Belgrade, Serbia

Introduction

Cell encapsulation by hydrogels is intended to shield transplanted cells from the host hostile environment by preventing the infiltration of host immune cells. Cell scaffolding by solid biocompatible microparticles is intended to provide a structural support to implanted cells and to mimic the extracellular matrix, allowing cells to proliferate and/or differentiate in the desired way. We present strategies to label scaffolding biomaterials with microenvironment responsive MRI probes, for applications in the follow-up of cell transplants.

Methods

Microparticles (MPs) based on PLGA/chitosan were incorporated with gadolinium fluoride nanoparticles (GdNPs), as the MRI T1-contrast agent. The system is designed such to release Gd-NPs in the extracellular matrix (ECM), thus activating MRI contrast, unless MPs are attacked by the immune system (Foreign Body Response, FBR). To proof the concept, PLGA-based MPs were seeded with hMSCs and implanted into either immunocompetent or immunocompromised mice, and the transplants were followed-up by MRI for three weeks. Ex-vivo histologic assessment was carried out at the end of the follow-up.

Results/Discussion

Immunocompetent mice showed poor activation, if any, of MRI contrast within the cell graft. Immunocompromised mice, on the other hand, showed a progressive activation of MRI contrast. Ex-vivo histology showed extensive FBR directed against microparticles in immunocompetent mice, with some surviving hMSCs in the ECM but not on the scaffold surface. No significant FBR was detected in immunocompromised mice, and hMSCs were still adhering to the scaffolds.

 

Conclusions

The proposed system is able to assess whether or not cell grafts are subjected to innate immune response, an event that is likely correlated to the loss of transplanted cells.

 

Acknowledgement

This work is supported by MAECI (PGR 02952 Italy and Serbia)

# 197

Mesoporous silica nanoparticles functionalized with Gd-complexes and cyclooctyne groups for bioorthogonal targeting (#455)

J. Martinelli1, F. Carniato1, D. Alberti2, S. Geninatti Crich2, C. Isidoro3, A. Lapadula3, L. Tei1

1 Università del Piemonte Orientale, Department of Sciences and Technological Innovation, Alessandria, Italy
2 Università di Torino, Molecular Biotechnology Center, Torino, Italy
3 Università del Piemonte Orientale, Department of Health Sciences, Novara, Italy

Introduction

Sialic acid,  a sugar overexpressed by cancerous cells,1 is an optimal candidate for molecular targeting. Azide-enriched sialic acid induced via metabolic glycoengineering can react with alkynes through cycloaddition reactions.2 We prepared mesoporous silica nanoparticles (MSNs)3 carrying cyclooctyne groups as targeting vectors. The particles were also functionalized with Gd-DOTAGA4 as magnetic resonance imaging (MRI) diagnostic probe, and rhodamine dyes to be exploited for optical imaging. The surface of the particles was covered with PEG to improve their hydrophilicity and biocompatibility.

Methods

MSNs were prepared through a typical sol-gel procedure and functionalized with aminoproyl groups.3 The organic functionalities were conjugated to the surface amines either directly (Rhodamine-NCS) or via common peptide coupling procedures (GdDOTAGA, MeO-PEG5000-COOH, Cyclooctyne-PEG3000-COOH). X-ray diffraction patterns, HRTEM images, IR spectra, TG and DLS data were measured for characterization. The magnetic field dependency of relaxivity (NMRD profiles) was measured on MSNs samples to determine the relaxometric parameters. Azide-enriched sialic acid was introduced by incubation of cells with tetraacetylated N-azidoacetyl-D-mannosamine. MRI at 3T and optical imaging studies were carried out on MCF7 and TS/A cells previously incubated with the azido-sugar and then with the nanoparticles.

Results/Discussion

The size of the final systems, as determined by dynamic light scattering, was in the range 25-50 nm. Compared to free Gd-DOTAGA complex, the MRI efficacy (evaluated in terms of relaxivity) resulted improved due to the longer reorientational correlation time as a consequence of the far higher global size of the agent (single molecule vs. particle). The Gd-loading, established by NMR and ICP measurements, was 0.17 mmol/g, affording a longitudinal relaxivity (r1p) of 11.5 mM-1 s-1. Preliminary data obtained by fluorimetry, fluorescence microscopy and mass spectrometry showed that engineered cells could be effectively targeted and labeled (on the surface) by our functionalized nanoparticles.

Conclusions

This study confirms both the usefulness of metabolic glycoengineering, and the great potential of multifunctional agents for bioorthogonal targeting and molecular imaging of cancer cells. Our systems seem to represent a valid opportunity for the development of multimodal and theranostic agents.

References

  1. Schauer R.; Glycoconjug. 2000, 17, 485;
  2. Friscourt F., Ledin P. A., Mbua N. E., Flanagan-Steet H. R., Wolfert M. A., Steet R., Boons G. J.; J. Am. Chem. Soc. 2012, 134(11), 5381-9;
  3. Carniato F., Muñoz-Úbeda M., Tei L., Botta M.; Dalton Trans. 2015, 44(41), 17927-17931;
  4. Eisenwiener K. P., Powell K. P., Maecke H. R.; Bioorg. Med. Chem. Lett. 2000, 10(18), 2133-2135.

Acknowledgement

The financial support of Compagnia di San Paolo (CSP-2014 THERASIL Project) is gratefully acknowledged.

Bioorthogonal targeting between alkyne-functionalized MSNs and N3-sialic acid on cancer cells
Keywords: Contrast agents, Tumor targeting, MRI, Nanoparticles, Multimodal
# 198

A novel probe for tumor imaging based on glycogen (#409)

D. Jirák1, A. Gálisová1, M. Jiratova1, M. Rabyk2, E. Sticova1, M. Hrubý2, M. Hájek1

1 Institute for Clinical and Experimental Medicine, Department of Diagnostic and Interventional Radiology, Prague, Czech Republic
2 Academy of Sciences of the Czech Republic, Institute of Macromolecular Chemistry, Prague, Czech Republic

Introduction

Glycogen as a natural polymer may be used as a drug delivery system for cancer theranostics1,2. Glycogen nanoparticles exhibit tumor-targeting properties, biocompatibility and biodegrability and could be modified with oxazolines that increase probability of accumulation in tumor tissue. Allowing the multimodal imaging, a gadolinium chelate (DOTA) and a near-infrared fluorescent dye (IR800) were added to a glycogen core. In this study, biodistribution and in vivo accumulation of the probes with (GOX) and without oxazoline (GG) were studied on tumor-bearing rats by MRI and fluorescence imaging.

Methods

Properties of the probes were assessed by r1 relaxometry (0.5T) and MR imaging (4.7T); as a reference was used a commercial agent gadoterate meglumine (GM). Tumors were induced in RNU nude rats by subcutaneous injection of HUH7 cells (5x106) above the hind leg. Three weeks after, T1-weighted MR images of tumor, liver and kidneys with resolution 0.25x0.25x1.5 mm3 were acquired before and after intravenous administration of GG, GOX and GM of two concentrations (0.04/0.02 mmol/kg, each group n=4). Relative CNR values of tumor, liver and kidneys normalized to muscle tissue were calculated at each time point (day 0-7). Near-infrared fluorescence was measured on optical imager. After in vivo examination, histological analysis was performed.

Results/Discussion

Relaxivity of GG probe (10.3 mM-1s-1) was higher compared to GM (4.2 mM-1s-1) and GOX (3.0 mM-1s-1). After intravenous administration in the animals, GG and GM were uptaken by the liver; although the amount of GOX was negligible (Fig. 1). All probes were accumulated in tumor tissue and importantly the signal of GG and GOX increased at day 7 while the signal of GM decreased (Fig. 2). Increased MR signal was found predominantly in the tumor center, where the presence of fibrosis and steatosis was excluded by histology. Moreover, histology did not reveal any prominent pathological changes in internal organs after glycogen-based probes administration. MR contrast enhancement in tumors was long-lasting with higher contrast increase of GG and GOX compared to GM suggesting continuous accumulation by EPR (Enhanced Permeability and Retention) effect. Oxazoline modification manifested low uptake in organs compared to GG.

Conclusions

Here, we showed suitable properties and non-toxicity of the novel glycogen-based compounds including tumor-targeting property. Higher MR signal in tumors with maximum after 7 days was found. Obtained results suggest a high potential of the tested probes for tumor diagnosis and treatment.

References

1. Aasen et al., Int. J. Mol. Sci 2015, 8;16(9):21658-80  

2. Galisova at al., ISMRM Proc 2016, No.2309

Acknowledgement

Supported by MH CR-DRO (Institute for Clinical and Experimental Medicine IKEM, IN00023001) and the Ministry of Health, Czech Republic (grant #15-25781A).

Figure 1
MR and fluorescent images of kidney (A, B) and liver (D, E) of the animals with injected glycogen-based probes. MRI images were acquired at the time of maximum MR signal enhancement. Fluorescent images were acquired after 7 days of examination. Comparison of relative CNR values calculated fromT1-weighted MR images of kidney s(C) and liver (F).
Figure 2

MR images and corresponding CNR maps (inserts) of tumor tissue after administration of glycogen-based probes (A). Calculated CNR values of tumors at various time points after injection of glycogen-based probes and gadoterate meglumine (GM) (B).

Keywords: multimodal imaging, drug delivery system, tumor, glycogen
# 199

Small-sized PEGylated iron oxide nanoparticles (IONP) for T1-enhanced MRI (#89)

T. Vangijzegem1, D. Stanicki1, S. Boutry2, Q. Paternoster1, R. N. Muller1, 2, L. Vander Elst1, 2, S. Laurent1, 2

1 University of Mons, Department of General, Organic and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, Mons, Hainaut, Belgium
2 Center for Microscopy and Molecular Imaging, Gosselies, Hainaut, Belgium

Introduction

In the biomedical field, IONP are well-known T2 contrast agents (CAs) for MRI. However, their success as T2 CAs has been hampered by several disadvantages such as the well-known "blooming-effect" or the intrinsic dark signal of T2-weighted MRI which can be confusing during diagnosis establishment1. Interestingly, it has been reported recently that a T1 effect is observable when decreasing the size of the particles below a critical value2.

This work reports the development of very small iron oxide nanoparticles (VSION) active as potential platforms for high-field (9,4T) T1 angioMRI applications.

Methods

VSION with a mean diameter of 3,5 ± 0,6 nm (PDI: 1.11) were obtained by thermal decomposition. The transfer of the iron oxide nanoparticles in aqueous media was then performed by means of a ligand exchange protocol with PEG-based ligands (4 PEG chainlength: PEG200, PEG400, PEG800 and PEG2000) anchored onto the nanoparticles surface through a biphosphonate moiety.

Results/Discussion

VSION transferred in aqueous media with PEG200 and PEG400 biphosphonate derivatives showed poor stability (probably due to a lack of interparticle steric repulsion with these ligands). However, VSION treated with PEG800 and PEG2000 biphosphonate derivatives demonstrated great stability in physiological media over a period of 3 months. The efficiency of both PEG800-VSION and PEG2000-VSION as T1 contrast agents was demonstrated through their excellent relaxometric properties (high r1 values and small r2/r1 ratios). Moreover, the demonstration of the T1 effect observed whether for PEG800-VSION and PEG2000-VSION was performed at 9.4T to confirm the high potential of these platforms for T1 high-field angio-MRI. Finally, in vivo evaluation of these platforms has been performed through i.v. injection on mice. Again, the stability of these systems was evidenced by their long circulation time (>2h) observed on T1-weighted MRI.

Conclusions

In this work, stable PEGylated VSION have been prepared. The potential of these nanoplatforms for T1 contrast-enhanced high-field angio-MRI has been evidenced through in vitro and in vivo experiments showing a remarkable contrast enhancement induced by the probes. However, further studies implying a complementary imaging modality as well as in vitro experiments are still to be done to assess the pharmacokinetics and toxicological properties of these nanosystems.

References

1. Kim, B. H. et al. J. Am. Chem. Soc. 133, 12624–12631 (2011).

2. Taboada, E. et al. Langmuir 23, 4583–4588 (2007).

Acknowledgement

This work was performed with the financial support of the FNRS, the ARC, the Walloon Region (Gadolymph, Holocancer and Interreg projects), the Interuniversity Attraction Poles of the Belgian Federal Science Policy Office and the COST actions. Authors thank the Center for Microscopy and Molecular Imaging (CMMI, supported by the European Regional Development Fund and Wallonia).

Keywords: Magnetic resonance imaging, Iron oxide nanoparticles, T1 contrast agents, PEGylation
# 200

Effects on nanoprobe biodistribution as a result of aging (#308)

S. Plaza-García1, P. Ramos-Cabrer1, 3, R. Piñol2, J. L. Murillo2, A. Millán2, S. Carregal-Romero1

1 CIC biomaGUNE, Magnetic Resonance Imaging, Donostia-San Sebastián, Spain
2 CSIC-Universidad de Zaragoza, ICMA, Zaragoza, Spain
3 Ikerbasque, Basque Foundation for Science, Bilbao, Spain

Introduction

The design of well-defined nanoparticles for diagnosis and drug delivery seems no longer a bottleneck and novel formulations emerge daily, broadening their biological applications. Now, the understanding of the facts that influence their fate in vivo is becoming a central issue. Different studies have shown a low effectiveness of active targeting or unexpected degradation of nanoprobes in vivo, as compared with in vitro results. [1] Here we show how aging, despite maintaining similar physicochemical properties, of nanoprobes, may seriously alter their biodistribution in vivo.

Methods

Iron oxide based nanoprobes were prepared by in situ precipitation in films of iron-polymer coordination compounds. [2] Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) have been used to characterize the nanoprobes. In vivo experiments were performed in n=12 BALB/cJRj female mice of 8 weeks of age (19.9±0.5 g), injected with 100 ul of solutions of 200 ugFe/ml of iron oxide nanoparticles (2 groups of n=6). T2 maps were acquired at 7T using a Bruker biospec system, prior and up to 240 min post injection of the contrast agent through the tail vein using a triggered MSME sequence (20 echoes of TE=8 ms; TR=2500 ms; Nav =2; Matrix = 160x160; FOV = 24x24 mm; 8-12 slices of 1 mm thickness in 2 slice slabs to cover liver, spleen and kidneys).

Results/Discussion

Hybrid nanocomposites based on iron oxide nanoparticles embedded in a polymer bead were prepared and used for the biodistrubution studies. The structure of these nanoprobes is formed by non-aggregated groupings of magnetic nanoparticles holded by a poly (4-vynil pyridine) (P4VP) chain by N-Fe coordination bonds and polyethylene glycol (PEGs) chains in radial positions solvated and facing the water interface. A set of freshly prepared nanoparticles (1 week maximum) was compared to an aged batch (>1 month) showing similar distribution of sizes, z potentials and morphology in TEM images (Fig. 1). After injection, the freshly prepared particles accumulated mostly in the kidneys of mice, while the aged ones mostly accumulated in liver and spleen (Fig. 2).  

Conclusions

Aging of nanoparticles may seriously affect the consistency of these materials without affecting their size or charge, but inducing a totally different biodistribution in vivo.

References

[1] M. Henriksen-Lacey et al. Bioconjugate Chem. 2016, 28, 212-21.

[2] L. M. A. Ali et al. J. Biomed. Nanotechnol. 2013 9, 1272–1285.

Acknowledgement

We want to acknowledge the Spanish ministry of economy and competence (SAF2014-53412-R) and the Basque Government (PC2015-1-05 (53-80)) for financial support. We also thank IKERBASQUE (the Basque foundation for Science) for funding PRC.

Figure 1.
 Electron microscopy images of the hybrid nanocomposites before (A) and after (B) aging. Dynamic light scattering measurements of the nanocomposites before (C) and after aging (D).
Figure 2.
Changes in R2=1/T2 detected in the kidney of a mouse injected with freshly prepared nanoparticles.
Keywords: Nanoparticles, MRI, Biodistribution, Iron oxides
# 201

New MF1-Gadolinium complex as MRI contrast agents via green chemistry. (#72)

N. Dechsupa1, J. Prommued1, S. Phruankham1, N. Ngasaman1, A. Wankaew1, J. Kantapan1

1 Chiang Mai University, Department of Radiologic Technology, Research Unit of Molecular Imaging Probes, Muang, Chiang Mai, Thailand

Introduction

There has been increasing interest in the research of flavonoids from plants, due to growing evidence of the versatile health benefits. In addition, flavonoid-metal complex has been focus as novel class therapeutic agents. Muthurajan et al. (2015) was synthesized and characterized quercetin-Gd(III) complex as MRI contrast agent. Bouea macrophylla (Maprang in Thai) is enriched sources of flavonoids. In this study, the maprang seed extract containing flavonoids so call “Maprang flavonoids” in fraction1 (MF1) was selected to complexation with Gd(III) ions as a new contrast agent for MR imaging.

Methods

MF1-Gd complex (1mM-MF1:100 mM-Gd(III)) via green chemistry was prepared in water with final volume 20mL. The reaction of MF1 and Gd(III) was proceeded in ultrasonic bath for 1h. The supernatant after centrifugation at 4100 rpm for 20 min was collected as MF1-Gd complex and used for further studies including a determination of light absorption spectrum by UV-Vis spectrophotometry, Gd-concentration using ICP-OES, relaxivity and in vitro imaging using 1.5T MRI, and toxicity in cancer cell lines by MTT assay.

Results/Discussion

An MF1-Gd complex is contained 27.17 mM-Gd, exhibit a maximum light absorption peaks at 215 and 278 nm. The r2/ r1 value of MF1-Gd in water and plasma was 1.4 (r1=35.35 mM-1.s-1) and 1.7 (r1=48.08 mM-1.s-1), respectively. MF1-Gd (0.05-2.5 mM-Gd) did not toxic to a small cell lung cancer (GLC4 & GLC4/adr) and erythromyelogenous leukemic cancer (K562 & K562/adr) cell lines. In addition, in vitro MRI studies of MF1-Gd in cancer cells showed T1-signals increasing compares to control as a function of dose and time incubation.

Conclusions

This study indicated that MF1-Gd complex has a high potential to be a new candidate for T1-contrast agent with a relaxivity 10-fold higher than a commercial GBCAs, Gd-DTPA and Gd-DOTA.

References

  1. FJ. Pérez-Cano and M Castell. Flavonoids, inflammation and immune System. Nutrients, 2016; 8: 659.
  2. S Selvaraj, S Krishnaswamy, V Devashya, S Sethuraman, and UM Krishnan. Flavonoid–Metal Ion Complexes: A novel class of therapeutic agents. Med Res Rev., 2014; 34 (4): 677–702.
  3. M Grazul and E Budzisz. Biological activity of metal ions complexes of chromones, coumarins and flavones. Coordin Chem Rev., 2009; 253: 2588–2598.
  4. T Muthurajan, P Rammanohar, NP Rajendran, S Sethuraman and UM Krishnan. Evaluation of a quercetin–gadolinium complex as an efficient positive contrast enhancer for magnetic resonance imaging. RSC Adv., 2015; 5: 86967-86979.
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Acknowledgement

Thank you the MSN Nature Solution Co., Ltd. for kindly provided maprang flavonoids.

Figure1

Optical and magnetic properties of MF1-Gd complex: (a) UV-Vis spectrum, (b) T1W-imaged, (c) Relaxation rate in plasma, and (d) T1-, T2-relaxivity values in water and plasma.

Figure2

In vitro MRI of MF1-Gd complex at 1.5T: T1W-imaged of small cell lung cancer cells with various dose (a) and time incubation (b); The increasing intensity (%) by the complex in a fashions of dose (c) and time incubation (d) in small cell lung cancer (GLC4, GLC4/adr) and erythromyelogenous leukemic (K562, K562/adr) cell lines.

Keywords: Maprang, flavonoid, MRI, contrast agent, green chemistry