Modified polysaccharides as potential 19F magnetic resonance contrast agents

• 3-Aminobenzotrifluoride-modified polysaccharides as 19F contrast agents.
• Narrow single or split 19F NMR signal between −63 and −63.5 ppm.
• T1 = 1 s, T2 = 0.2 s at 400/500 MHz.
• Low toxicity, preferentially localized in lysosomes of HeLa cells.
• Not trapped in liver, spleen or kidneys, quickly cleared with urine.

The introduction of 3-aminobenzotrifluoride into partially oxidized alginic acid, dextran, and polygalacturonic acid (10–100 kDa) by means of the imine formation and a subsequent reduction resulted in water-soluble materials containing 1–14% of fluorine. They showed a single or split 19F NMR signal in a narrow range of −63 to −63.5 ppm. The observed T1 and T2 were approximately 1 and 0.2 s at 400 or 500 MHz instruments, respectively. The samples showed low toxicity and uptake toward the HeLa cells similar to native polysaccharides and were preferentially localized in lysosomes. A tail intravenous injection of 5 mg of modified dextran containing 1% of fluorine revealed that the probe was not trapped in liver, spleen or kidneys, but was quickly cleared with urine. The proposed materials can be used for imaging of the gastrointestinal tract or the genitourinary system and act as a material for more complex 19F MRI agent synthesis.

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