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Characterisation and evaluation of paramagnetic fluorine labelled glycol chitosan conjugates for ¹⁹F and ¹H magnetic resonance imaging

Lookup NU author(s): Professor Andrew BlamireORCiD

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Abstract

Medium molecular weight glycol chitosan conjugates have been prepared, linked by an amide bond to paramagnetic Gd(III), Ho(III) and Dy(III) macrocyclic complexes in which a trifluoromethyl reporter group is located 6.5 from the paramagnetic centre. The faster relaxation of the observed nucleus allows modified pulse sequences to be used with shorter acquisition times. The polydisperse materials have been characterised by gel permeation chromatography, revealing an average molecular weight on the order of 13,800 (Gd), 14,600 (Dy) and 16,200 (Ho), consistent with the presence of 8.5, 9.5 and 13 complexes, respectively. The gadolinium conjugate was prepared for both a q = 1 monoamide tricarboxylate conjugate (r (1p) 11.2 mM(-1) s(-1), 310 K, 1.4 T) and a q = 0 triphosphinate system, and conventional contrast-enhanced proton MRI studies at 7 T were undertaken in mice bearing an HT-29 or an HCT-116 colorectal tumour xenograft (17 mu mol/kg). Enhanced contrast was observed following injection in the tail vein in tumour tissue, with uptake also evident in the liver and kidney with a tumour-to-liver ratio of 2:1 at 13 min, and large amounts in the kidney and bladder consistent with predominant renal clearance. Parallel experiments observing the F-19 resonance in the holmium conjugate complex using a surface coil did not succeed owing to its high R (2) value (750 Hz, 7 T). However, the fluorine signal in the dysprosium triphosphinate chitosan conjugate [R (1)/R (2) = 0.6 and R (1) = 145 Hz (7 T)] was sharper and could be observed in vivo at -65.7 ppm, following intravenous tail vein injection of a dose of 34 mu mol/kg.

Publication metadata

Author(s): De Luca E, Harvey P, Chalmers KH, Mishra A, Senanayake PK, Wilson JI, Botta M, Fekete M, Blamire AM, Parker D

Publication type: Article

Publication status: Published

Journal: Journal of Biological Inorganic Chemistry

Year: 2014

Volume: 19

Issue: 2

Pages: 215-227

Print publication date: 17/08/2013

ISSN (print): 0949-8257

ISSN (electronic): 1432-1327

Publisher: Springer

URL: http://dx.doi.org/10.1007/s00775-013-1028-y

DOI: 10.1007/s00775-013-1028-y

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