Synthesis of Gadolinium Complexes Using Medicinal Plant Extracts

Background: Gadolinium compounds are used as contrast enhancers in MRI imaging. Generally, free metal ions are not used in MRI imaging due to their toxicity. To reduce the toxicity of the free form of the metal, complexing agents are employed for making nanoparticles. Due to their low toxicity and natural abundance, plant extracts having potential to function as chelating agents are good alternatives for the formation of gadolinium nanoparticles. Methods: Aqueous extracts of five plant species, including Thymus daenensis Celak, Nepeta sessilifolia Bung, Crocus sativus L., Salvia hydrangea DC. ex Benth, and Hymenocrater incanus Bunge were prepared. Five complexes were produced as the result of each extract’s reaction with gadolinium nitrate solution in the presence of ۱ mM solution of NaOH. The obtained complexes were analyzed adopting the Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy dispersive x-ray analysis (EDAX) techniques. Results: EDAX analysis of the obtained complexes confirmed the presence of gadolinium in all complexes. Among the five complexes, the highest percentage of gadolinium (۲۱.۰۷) was recorded for the complex derived from the extract of H. incanus Bunge, while the lowest one (۹.۳۳) was detected for the complex derived from the T. daenensis Celak. Despite adopting various methods to disperse the complex particles in deionized water in order for determining the particle size, the high adhesion of the particles prevented the determination of the desired particle size in nanoscale. Conclusion: Although synthesizing the complexes was successful and EDAX confirmed the presence of gadolinium metal in them, SEM analysis failed to prove their nanoparticle structure. The high tendency of solid particles to adhere was found to prevent the formation of independent nanoparticles in solution.

Keywords:

Gadolinium complexes , Medicinal plants , Extract , MRI imaging