The Study Of Mr Imaging In Triple Negative Breast Cancer Model By A Novel Nanoparticle Mitochondria Targeting Probe Gestated By Magnetotactic Bacteria—magnetosomes

Bacterial magnetic particles (BMP) gestated by magnetotactic bacteria have attracted broad attention because of their unique structures, novel properties and wide potential applications in chemistry, physics, material science and medicine. With a view to potential application as high-efficient and low-toxic MRI contrast agents of next generation. In this paper, we synthesized several kinds of MRI contrast agents based on magnetotactic bacteria AMB-1and explored their relaxivity of water proton and aggregate behavior. Most significantly, the introduction of functional groups on cage provided them potential as cell-targeted MRI diagnostic material. Some meaningful and achieved results are as followed.Purpose:1.To prepare biological nanoparticle magnetosomes, which is active targeting mitochondrial by cytochrome c (Cyt c) and modified by polyethylene glycol (PEG), named PEG-cBMP;2. To detect the characteristic targeting of PEG-cBMP in the triple negative breast cancer cells MDA-MB-231and the relaxitivity and effect of its MR imaging in Vitro.Experimental material and methods:1. Cultured magnetotactic bacteria AMB-1and verified whether they had magnetosomes in the cells by transmission electron microscopy (TEM). Additionally, the magnetosomes were extracted and purified by centrifugation, washed repeatedly and they were characterized by transmission electron microscopy (TEM), X-ray diffraction(XRD), energy dispersive spectroscopy(EDS), Fourier transform infrared spectroscopy(FT-IR), hysteresis loop, zeta potential, inductively coupled plasma mass spectrometry(ICP-MS) and Atomic absorption spectroscopy(AAS).2. The BMP bind cytochrome c (Cyt c) on the5’terminal and modified Alexa Flour647on the3’terminal. By ultrasonic oscillation, we got the product named Cyt c-BMP (cBMP). It should be active targeting mitochondria.3. We connected cBMP and PEG by NHS/EDC crosslinking, named PEG-cBMP. PEG was modified by methoxy group and a carboxyl group in the ends respectively and its molecular weight is2000Da, named M-PEG-COOH2000.4. To detect the PEG-cBMP had active targeting or not, we incubated the PEG-cBMP, mito-tracker green and hoechest33342with triple negative breast cancer cells MDA-MB-231respectively and checked the interaction of them by laser confocal scanning microscope and transmission electron microscopy. Furthermore, we scanned cells by a clinical3.0T MR imaging scanner.Results:1. We have successfully prepared PEG-cBMP and characterized by various methods including transmission electron microscopy (TEM), X-ray diffraction(XRD), energy dispersive spectroscopy(EDS), Fourier transform infrared spectroscopy(FT-IR), hysteresis loop, zeta potential, inductively coupled plasma mass spectrometry(ICP-MS).2. On the other hands, the PEG-cBMP have been proved to having active targeting mitochondria through incubated with triple negative breast cancer cells MDA-MB-231surported by laser confocal scanning microscope and transmission electron microscopy;3. Furtheremore, we observed that the signal of MDA-MB-231cells declined with the increased concentration of the PEG-cBMP. The transverse relaxitivity rate (R2) is1062.264(mmol-1·L·s-1). All of those indicated that the PEG-cBMP is an excellent T2contrast agent. Conclusion:The magnetosomes (BMP) extracted from magnetotactic bacteria AMB-1and the modified by PEG and cytochrome c, we called PEG-cBMP, which is a better biocompatibility and active targeting mitochondria. Meanwhile, the PEG-cBMP is an excellent T2contrast agent.