Preparation Fluorescent Iron Oxide Nanoparticles (CNPCP)

Chitosan-PEG coated iron oxide nanoparticles with CD incorporated (CNPCP) were synthesized via co-precipitation as previously reported (Veiseh et al., 2009). Briefly, purified chitosan (3.9 kDa) and aldehyde-activated methoxy PEG were reacted via reductive amination to produce a PEG-grafted chitosan polymer (CP). To synthesize the CD-CP complex, purified CP (150 mg) and glucosamine hydrochloride (25 mg) was dissolved in deionized water. Diluted ammonia was added at 12.5 mg/ml. The solution was then transferred to a capped glass vial, and placed inside a conventional microwave. The vial was irradiated at 300W for varied duration. The resulting fluorescent CD-CP was purified through size exclusion chromatography in S-200 resin (GE Healthcare, Piscataway, NJ, United States) equilibrated with deionized water.

To synthesize the CNPCP, polymer mixture consisting of varied ratios of CP and CD-CP (150 mg total), iron (II) chloride (9 mg), and iron (III) chloride (15 mg) were dissolved in degassed deionized water (2.18 ml). Ammonia solution (36%) was titrated into the solution while being sonicated and stirred vigorously for 25 min under a nitrogen atmosphere. The ammonia was evaporated from the solution by continuing the sonication and stirring for additional 20 min to continue the growth of the nanoparticles. The resulting CNPCP were purified using S-200 resin equilibrated with deionized water.