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Site-Specific Amphiphilic Magnetic Copolymer Nanoaggregates for Dual Imaging

Mukherjee, Saikat, Dinda, Himadri, Shashank, Litesh, Chakraborty, Ipsita, Bhattacharyya, Rangeet, Das Sarma, Jayasri, Shunmugam, Raja
Macromolecules 2015 v.48 no.19 pp. 6791-6800
Fourier transform infrared spectroscopy, ambient temperature, biocompatibility, cell viability, cobalt, composite polymers, energy-dispersive X-ray analysis, flow cytometry, folic acid, image analysis, magnetic resonance imaging, magnetism, neoplasms, nuclear magnetic resonance spectroscopy, polyethylene glycol, polymerization, scanning electron microscopy, transmission electron microscopy
Molecular imaging along with combinations of imaging modalities can provide a thorough understanding of disease, in particular, tumors. Magnetic resonance imaging (MRI) offers exceptional tissue contrast and resolution; whereas optical imaging provides high sensitivity. Hence a norbornene based copolymer (Nor-Cob-Py-Fol) is reported in this paper as a dual-imaging agent. Nor-Cob-Py-Fol having Co²⁺ complex, pyrene and poly(ethylene glycol) derived folate, have been synthesized using ring-opening metathesis polymerization (ROMP). All the monomers and polymers are characterized by ¹H NMR, IR, GPC, and TGA techniques. The morphology of the copolymer nanoaggregates has been evaluated with DLS, TEM, and SEM techniques. The functionalization of Co²⁺ to the polymer is monitored by FTIR, ¹H NMR, and ¹³C NMR spectroscopy. Furthermore, the presence of Co²⁺ in the nanoaggregates is confirmed by the EDX (SEM) technique. To prove the MRI capabilities nature of copolymer nanoaggregates, NMR experiment is performed at room temperature. Cell viability studies suggest the biocompatibility nature of the copolymer. Flow cytometry as well as epifluoroscence microscope experiments clearly demonstrate the dual-imaging ability of the newly designed copolymer. The much higher relaxivity ratio (r₂/r₁) of the present method clearly establishes the superiority of our system as one of the best contrast agents known to the practitioners of magnetic resonance imaging.