Gd‐DTPA‐Dopamine‐Bisphytanyl Amphiphile: Synthesis,Characterisation and Relaxation Parameters of the Nanoassemblies and Their Potential as MRI Contrast Agents |
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| Authors: | Abhishek Gupta Dr Scott A Willis Lynne J Waddington Dr Tim Stait‐Gardner Dr Liliana de Campo Prof Dennis W Hwang Dr Nigel Kirby Prof William S Price Dr Minoo J Moghaddam |
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| Affiliation: | 1. Manufacturing Flagship CSIRO, P.O. Box 52, North Ryde, NSW, 1670 (Australia);2. Nanoscale Organisation and Dynamics Group, University of Western Sydney, Penrith, NSW, 2751 (Australia);3. Manufacturing Flagship CSIRO, 343 Royal Parade, Parkville, VIC, 3052 (Australia);4. Bragg Institute ANSTO, Lucas Heights, NSW, 2234 (Australia);5. Department of Chemistry and Biochemistry, National Chung Cheng University, Min‐Hsiung Township Chiayi, 621 (Taiwan);6. Australian Synchrotron, 800 Blackburn Road, Clayton, VIC, 3168 (Australia) |
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| Abstract: | Here, a new amphiphilic magnetic resonance imaging (MRI) contrast agent, a GdIII‐chelated diethylenetriaminepentaacetic acid conjugated to two branched alkyl chains via a dopamine spacer, Gd‐DTPA‐dopamine‐bisphytanyl (Gd‐DTPA‐Dop‐Phy), which is readily capable of self‐assembling into liposomal nanoassemblies upon dispersion in an aqueous solution, is reported. In vitro relaxivities of the dispersions were found to be much higher than Magnevist, a commercially available contrast agent, at 0.47 T but comparable at 9.40 T. Analysis of variable temperature 17O NMR transverse relaxation measurements revealed the water exchange of the nanoassemblies to be faster than that previously reported for paramagnetic liposomes. Molecular reorientation dynamics were probed by 1H NMRD profiles using a classical inner and outer sphere relaxation model and a Lipari–Szabo “model‐free” approach. High payloads of GdIII ions in the liposomal nanoassemblies made solely from the Gd‐DTPA‐Dop‐Phy amphiphiles, in combination with slow molecular reorientation and fast water exchange makes this novel amphiphile a suitable candidate to be investigated as an advanced MRI contrast agent. |
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| Keywords: | contrast agents gadolinium‐DTPA‐amphiphiles liposomes 17O NMR spectroscopy relaxation |
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