Synthesis Of MnCo₃@PDA Nanocomposite And Its Applications In Magnetic Resonance Imaging And Photothermal Treatment

The diagnosis and therapy of tumor,especially for early diagnosis and therapy of high deadly and invasive tumor has gained more and more attention.However,similar to therapy of cancers,it is still a great challenge to realize the early diagnosis of cancer.In terms of tumor diagnosis,methods including the X ray computed tomography(CT),magnetic resonance imaging(MRI),ultrasound imaging(US),and now the more popular diagnostic method of photoacoustic imaging(PAI)have been drawn much attention.However,owing to the intrinsic properties such as the high spatial resolution,noninvasiveness of MRI,it has been widely investigated and applied in biomedicine.In terms of therapy of tumor,photothermal therpy(PTT)has been drawn much attention for its noninvasiveness,low side effects,high efficiency and selectivity.Thus,in our work,we provide a very simple method,for the first time,to fabricate multifunctional MnCO3@PDA nanoparticles(NPs)at room temperature.The as-made core/shell MnCO3@PDA nanocomposite realized the multi-function combined MRI and PTT in a signal nanoplatform.The main work in this paper can be included to as follows:1.Solventhermal,coprecipitation and microemulsion mediated method have been used to synthesize MnCO3 nanoparticles.Powder X-ray diffraction(XRD)had been applied to confirm the composition and its crystalline structures of MnCO3 NPs.Meanwhile,the morphology and size of the synthesized MnCO3 NPs were characterized by transmission electron microscopy(TEM)and scanning electron microscope(SEM).In order to have a better application in biomedicine,we choose the NPs with relative small size for further study in our experiment.2.Compared with MnCO3 NPs synthesized by solventhermal and coprecipitation method,the MnCO3 NPs synthesized by microemulsion mediated method are smaller with side length of 100 nm.In order to improve the dispersibility of NPs,water-soluble PAA ligand was applied to modify MnCO3.Severe changes in Zeta potential showed the successful modification of PAA on the surface of MnCO3 NPs.Afterwards,MnCO3@PDA core/shell NPs were obtained by self-polymerization of dopamine in Tris-HCl buffer solution(pH～8.5).The thickness of polydopamine can be controlled by regulating the amount of dopamine.The in vitro MRI and photothermal effect of the as-prepared MnCO3@PDA NPs showed a great potential application in MRI guided PTT.3.Inspired by the excellent in vitro MR contrast and photothermal performance of MnCO3@PDA NPs,we further did the related experiment on cells and animals.The MnCO3@PDA NPs showed a low cellular toxicity after being coated with PDA shell.However,most cells had been killed after being dealt with NIR laser,which further indicated the potential ability of photothermal to kill cancer cells.In vivo experiments further indicated that the MnCO3@PDA NPs could be an excellent therapeutic agent for imaging guided PTT.Thus,the versatile nanoplatform integrated MRI and PTT drew on the strong points to accurate diagnosis and also a comparable effect at the aspect of therapy.