| Objective:At present, cancer is a serious threat to human health. The early diagnosis and treatment of the tumor can reduce the risk of cancer mortality in great extent. It is an urgent problem to find a new diagnostic and therapeutic reagent for the early diagnosis and treatment of tumors. In recent years, nanocomposites containing two or more kinds of nanoparticles have attracted much attention due to their unique properties respectively. In this work, a computed tomography(CT) contrast agent containing gold and iodine nanocomposites was prepared. The nanocomposites could achieve not only cancer diagnosis with high sensitivity, but also the tumor ablation under the guidance of imaging due to the strong absorption properties of gold nanoshell in the near infrared area.Contents:The hyaluronic acid(HA) modified iodinated nanoparticles/Au shell nanocomposites were prepared successfully by multi-steps, including the synthesis of iodine-containing monomer compound, the preparation of iodinated nanoparticles, the coating of Au nanoshell and the modification of HA. Their structures and properties were characterizated by 1H-NMR spectrum, transmission electron microscope(TEM), energy dispersive X-ray spectroscopy(EDX), dynamic laser scattering(DLS), Fourier transform infrared spectrometer(FT-IR), ultraviolet-visible-near infrared absorption spectrometer(UV-vis-NIR) and CT scanner etc. The cellular uptake and cytotoxicity of nanocomposites were investigated in vitro. The properties of CT imaging and photothermal therapy were evaluated in vivo by injecting the nanocomposites into the tail vein of tumor-bearing nude mice.Methods : The iodine-containing monomer 2-methacryl(3-amide-2, 4, 6-triiodobenzoic acid(MATIB) was first synthesised through an amidation reaction between 3-amino-2, 4, 6-triiodobenzoic acid and methacrylic chloride. Then the iodinated nanoparticles poly(2-methacryl(3-amide-2, 4, 6-triiodobenzoic acid)) PMATIB were synthesized by precipitation polymerization with MATIB as the monomer, N, N-methylene bisacrylamide(MBAAm) as the crosslinker and azodiisobutyronitrile(AIBN) as the initiator. The PMATIB/PEI nanoparticles were prepared by electrostatic interaction between the PMATIB and polyethylene polyimide(PEI), and further interacted with Au NPs by the same method to form PMATIB/PEI/Au NPs. Au nanoshells were formed by using a seed-mediated method and subsequently surface modified with HA to form the resultant poly(2-methacryl(3-amide-2, 4, 6-triiodobenzoic acid))/ polyethyleneimine/ Au nanoshell/ hyaluronic acid(PMATIB/PEI/Au nanoshell/HA) nanocomposites.Next, the nanoparticles generated from every step were characterized comprehensively. Nuclear magnetic resonance spectrometer(1H-NMR) was used to determine the chemical structure of the monomer. TEM was used to observe the surface morphology of the nanoparticles. DLS was used to investigate the size and size distribution, surface charges and colloid stability of the nanoparticles. EDX was used to determine the elements composition of PMATIB/PEI/Au nanoshell/HA nanocomposites. FT-IR and UV-vis-NIR spectra were used to determine the chemical structures of the nanoparticles. MTT assay was used to investigate the cytotoxicity and TEM was used to observe the cellular uptake of PMATIB/PEI/Au nanoshell/HA nanocomposites. The X-ray absorption properties and CT imaging in vitro and in vivo were acquired using a PHILIP MX-16 SLICE clinical system. Infrared camera was used to observe the tumor photothermal imaging of the tumor-bearing mouse. The tumor ablation result was observed and further investigated from the tumor tissue necrosis by H&E staining.Results :The structure of the monomer MATIB was confirmed by 1H-NMR spectrum. TEM images showed the uniform size and good dispersity of the nanoparticles from every step. The average particle size of the PMATIB/PEI/Au nanoshell/HA nanoparticles was 187 nm. The core shell structure of PMATIB/PEI/Au nanoshell/HA containing I, Au, N, O and C etc was confirmed by EDX energy spectrum analysis. The results of DLS measurement showed the good dispersity and colloidal stability of the nanocomposites. The Zeta potential of PMATIB, PMATIB/PEI and PMATIB/PEI/Au nanoshell/HA were-56.5±0.20 m V, +35.0±0.20 m V and-24.8±0.26 m V, respectively, which indicated the successful modification of the substances in every step. The results from FT-IR and UV-vis-NIR spectra indicated the successfully preparation of PMATIB/PEI/Au nanoshell/HA nanocomposites.The cellular viability evaluated by MTT assay was 82.1% at the concentration of 50 ?g Au m L-1, suggesting the relatively low cytotoxicity of the nanocomposites. The growth of tumor cells was inhibited significantly at the PMATIB/PEI/Au nanoshell/HA concentration of 25 ?g Au m L-1 under NIR laser irradiation. The nanocomposites showed the better cellular uptake ability from the observation of TEM images.The results of CT scanning indicated that the PMATIB/PEI/Au nanoshell/HA nanocomposites showed the better X-ray attenuation performance and could be deposited in the tumor site with a large number of, resulting in the enhancement of CT imaging contrast of the tumor site. The PMATIB/PEI/Au nanoshell/HA solution can be heated to 50 ?C at the concentration of 50 ?g Au m L-1 under the laser irradiation(808 nm,1.4 W cm-1), indicating their good photothermal conversion performance. After a MCF-7 tumor-bearing nude mice being intravenously injected with PMATIB/PEI/Au nanoshell/HA for 6 h, the tumor area of the mice could be heated to above 60 ?C under the laser irradiation(808 nm,3 W cm-1). The result of H&E staining and pathological examination showed the tumor tissue necrosis after irradiation.Conclusions : The PMATIB/PEI/Au nanoshell/HA nanocomposites were successfully prepared in this work. The nanocomposites showed good photothermal effect, X-ray attenuation property and relatively low cytotoxicity. PMATIB/PEI/Au nanoshell/HA nanocomposites could be deposited at the tumor site with a large number of and enhance the CT imaging contrast of the tumor. The NIR photothermal tumor ablation was realized under the guidance of CT imaging. Therefore, PMATIB/PEI/Au nanoshell/HA nanocomposites have great potential applications in CT imaging and CT imaging guided photothermal therapy of tumor. |
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