| Purpose:By using nanotechnology,we aimed to construct a multimodal MR/CT/fluorescence imaging nanoprobe with high targeting specificity,imaging sensitivity and long circulation properties,and apply it to in vitro cellular imaging as well as in vivo targeted imaging,thus lay a foundation for early precise diagnosis and noninvasive dynamic monitoring of prostate cancer at the molecular level.Methods:We utilize the over-expressed prostate-specific membrane antigen(PSMA-1)as molecular target,employ the human autologous short peptide and important antioxidant glutathione(GSH)as template as well as reducing agent,to synthesize the ultra-small gold nanoparticles(Au NPs).Then the magnetic resonance imaging(MRI)component Gd-DTPA was decorated,and the resulting PSMA targeted high-resolution MRI/CT/fluorescence multimodal molecular imaging probe(PSMA-1-gold-gadolinium NPs)was successfully constructed.Then we characterize their physicochemical characteristics,biocompatibility as well as their biodistribution.The cytotoxicity and biosafety of the prepared PSMA-1-gold-gadolinium NPs were investigated through the cell MTT assays,in vivo weight monitoring,blood biochemical analysis and intravital metabolism.Then PSMA-1-gold-gadolinium NPs were injected to the xenograft nude mice model of human prostate cancer,and in vivo MRI/CT/fluorescence imaging were performed respectively to observe the probe distribution and aggregation in prostate cancer tissues.The load and nature of prostate cancer were evaluated by dynamically monitoring the T1 signal intensity(SI)and contrast to noise ratio(CNR).Ultimately,histological quantitative examinations were carried out to verify the targeting efficacy of the probe.Results:(1)The PSMA-1-gold-gadolinium NPs were successfully fabricated.They had ultra-small,uniform diameter and superior colloidal stability.(2)In vitro MR imaging showed the T1 relaxivity of PSMA-1-gold-gadolinium NPs was about 24.0 m M-1·s-1,suggesting it fit for high-efficiency T1-weighted imaging.In vitro CT imaging demonstrated stronger X-ray attenuation characteristics of PSMA-1-gold-gadolinium NPs compared to traditional iodine-containing contrast agents.Fluorescence spectrum of PSMA-1-gold-gadolinium NPs displayed the characteristic emission peak at 600 nm,demonstrating admirable capabilities for fluorescence imaging.(3)The cell MTT assays,in vivo weight monitoring,blood biochemical analysis as well as intravital metabolism verified low cytotoxicity and high biosafety of our prepared PSMA-1-gold-gadolinium NPs,which was suitable as a contrast agent for prostate cancer targeted multimodal molecular imaging in vivo.(4)In vitro cellular binding experiments revealed high affinity of PSMA-1-gold-gadolinium NPs for the prostate cancer cell line(PC3pip)with the PSMA over-expression.Significant red fluorescence was observed in the PC3pip cells co-cultured with the targeted nanoparticles,whereas only individual PC3flu cells displayed faint red fluorescence.Only a small amount of red fluorescence was also found in the PC3pip cells co-cultured with non-targeted nanoparticles.Then in vitro cellular MRI also showed the same result that the PC3pip cells displayed high T1signals in time-dependent and concentration-dependent manner after co-incubation with targeted PSMA-1-gold-gadolinium NPs.While,there was only low T1 signals in the PC3flu groups as well as in the PC3pip group co-cultured with non-targeted nanoparticles.(5)In vivo dynamic MR/CT/fluorescence multi-modality imaging of the PC3pip xenograft nude mice model exhibited that the T1 signal intensities,CT values and fluorescence signal intensities of tumor tissues were significantly enhanced and peaked at 6 h after the PSMA-1-gold-gadolinium NPs injection.More importantly,these signal enhancements in tumor tissues could be sustainable within 24 hours.However,dynamic MR/CT/fluorescence images of the PC3flu xenograft nude mice model displayed only slight enhanced signals in tumor tissues after the PSMA-1-gold-gadolinium NPs injection.The tumor signal enhancements in the PC3pip groups was particularly apparent than that in the PC3flu groups(p<0.05),which were statistically significant.(6)A series of histopathological examinations including immunohistochemical staining and silver-staining of tumor tissues confirmed that the PSMA-1-gold-gadolinium NPs indeed aggregated in the PAMA-1 over-expressed tumor tissues.Conclusion:A prostate cancer-targeting MR/CT/fluorescence multimodal molecular imaging probe PSMA-1-gold-gadolinium NPs was successfully constructed,which possessed multiple advantages of facile synthesis procedure,excellent biocompatibility,admirable targeting ability,high imaging sensitivity,as well as long-circulation properties.More importantly,the developed nanoprobe PSMA-1-gold-gadolinium NPs could dynamically provide multitudinous pathological information of early prostate cancer from various perspectives.It provided a novel strategy and reliable basis for early prostate cancer diagnosis at molecular level,and held great potential in clinical prostate cancer diagnosis and treatment applications. |
PDF Full Text Request