| Due to the limitations of traditional methods,the cure rate of cancer has been difficult to improve.New methods,such as photothermal therapy assisted by nanomaterials,have become a new hope.Photothermal therapy has smaller cut,lower biotoxicity and can precisely locate the lesion assisted by gold nanorods.Medical imaging plays an important role in the diagnosis of cancer,CT and MRI are the most common imaging modalities in clinical practice.Contrast agents can enhance image quality and provide more physiological and pathological information for diagnosis while dual-mode or multi-mode contrast agents can further improve the diagnostic efficiency.Nanomaterials with diagnostic and therapeutic functions can do some treatment at the same time of diagnosis and feedback pathological information during treatment.We try to use a few simple steps to synthesize effective contrast agent for dual CT/MR Imaging mode.The seed-mediated growth method was used to synthesize Au NRs.To stabilize these obtained Au NRs,they were modified with HOOC-mPEG-SH due to the formation of the Au-S bonds.4-amino-2,2,6,6-tetramethylpiperidine-N-oxide(4-Amino-TEMPO)was connected to Au NRs through a NHS/EDC catalyzed-COOH/-NH2 condensation reaction.Au NPs were reported as an effective CT contrast agent because higher attenuation of X-ray and lower cytotoxicity than clinically used iodixanol,while rod-shaped Au NPs(Au NRs)can also be used for photothermal therapy.Au NRs can kill cancer cells,inhibit tumor proliferation and improve survival rate of mice under near infrared laser irradiation.4-Amino-TEMPO was convinced to have strong signals in T1-weighted MR imaging and can be used as free radical sensor.Modifying mPEG can enhance water solubility and biocompatibility,extend cycle time and working time.We convince that this kind of Au-TEMPO NRs,integrating the abilities of CT/MRI imaging and photothermal therapy abilities,can play an active role in the imaging guided photothermal cancer therapy. |
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