Breast Cancer Angiogenesis CT Imaging Using Gold Nanoparticle Probe With Directly Conjugated Cyclic NGR

Purpose:To explore a one-step modified method of GNPs functionalized with the SH-cNGR which can specifically target tumor angiogenesis,and to explore characterization and biocompatibility of the probe and evaluate breast cancer angiogenesis CT targeted imaging effect.Methods:Firstly,GNPs were synthesized by the citrate reduction of HAuCl₄·4H₂O.Then,surface-functionalized modification with cyclized NGR peptide?SH-cNGR?and SH-PEG-COOH via Au-S bonds were conducted respectively by one-step method.The characterizations of the GNPs-PEG@cNGR probe were analyzed by using various devices and instruments,such as transmission electron microscopy?TEM?and fourier Transform Infrared Spectroscopy?FTIR?.Then,the in vitro CT imaging potential and toxicity of the probe were evaluated.The cell uptake and binding analysis of the probe were assessed by Laser scanning confocal microscopy?LSCM?imaging and CT imaging.In vivo CT imaging was performed in 4T1 xenografts to assess the targeted imaging potential and biocompatibility of the probe.Contents:?1?About 13 nm GNPs was synthesized by classic sodium citrate reduction method of HAuCl₄·3H₂O,then hydrophilic and targeted modification for GNPs were conducted.Under the premise of stable physical and chemical properties of GNPs,targeted CT imaging capability and the biocompatibility of the probe were explored.?2?The GNPs-PEG@cNGR probe with SH-cNGR serving as targeting ligand and SH-PEG-COOH as hydrophilic substances was synthesized by an one-step method.Its characterizations and CT imaging potential in vitro were discussed.?3?To investigate the cell toxicity and CD13 positive cell targeting of probe,and to verify the tumor targeting potential in vivo and the relationship between tumor angiogenesis distribution and tumor targeted enhancement pattern.Results:?1?TEM images shown the size of the probe was uniform and about 33 nm,and the dispersibility was excellent.Hydration kinetic diameter size is 35±1.4 nm,surface Zeta potential is-13±1.12 mV.FTIR spectra showed Amide I bond(1631 cm^-1,carbonyl stretch vibration)and amide III bond(1384 cm^-1,C-N stretch vibration)appeared in probe.?2?In vitro CT imaging showed that CT value of the probe was higher than that of Iohexol at same concentration of[Au or I],which attributed to the higher atomic number of Au than that of iodine.?3?The cytotoxicity result of MTT showed that all cells viability was greater than 85%,which confirmed the probe have a good biocompatibility and access to imaging in vivo/vetro.?4?LSCM imaging showed the HUVEC cells incubated with the probe exhibited much stronger green fluorescence than that treated with GNPs-PEG.CT imaging quantitative analysis showed the HepG2 cells incubated with the probe showed significantly higher X-ray attenuation than that treated with the GNPs-PEG?p<0.01?.?5?4T1 xenograft model was constructed,and the potential of the in vivo tumor CT imaging was explored.The result showed that the tumor areas have an faster,higher and longer enhancement in postinjection with probe compared with the tumors of mice injected with the GNPs-PEG.?6?Immunohistochemical analysis showed the relationship between the distribution of tumor angiogenesis and intratumoral CT enhancement region have statistical correlation,which confirmed the probe can assess tumor angiogenesis and provide a gateway for accessing the metastasis and malignancy of the tumor.Conclusion:The GNPs-PEG@cNGR was prepared by one step functionalization method,and the synthesis method is simple.The probe have good dispersion,uniform particle size,good biocompatibility,great potential of CT imaging and CD13 targeting effect.It is a feasible method to evaluate the tumor angiogenesis with the help of probe,which is of great significance to clinical assessment of tumor benign malignancy and metastasis risk.