Biosynthetic Of Protein-based Tumor-targeted Imaging Probe For Bimodal Imaging

The advent of molecular imaging technology has opened the door to noninvasive visualization of tumors in living organisms,various molecular imaging probes have been rapidly developed and studied.Some imaging probes have shown good imaging results in tumor imaging,but their potential biological safety is difficult to predict,which limits their further clinical application.Protein-based imaging probes have attracted much attention due to their good biocompatibility,flexible design and good imaging results.This paper focuses on the design,synthesis,performance and biological application of protein-based imaging probes.The main research work is summarized as follows:In chapter one,we mainly introduced the molecular imaging technology and some imaging probes used in clinical practice,and then introduce the composition and function of protein-based multimodal imaging probes,and finally put forward the significance and research content of this subject.In chapter two,the synthesis and characterization of fusion protein RGD-RFP-LBT.Through genetic engineering technology,the gene sequences corresponding to the targeted module RGD,the red fluorescent protein RFP and the rare earth ion binding tag LBT were inserted into the genome of E.coli,and the fusion protein RGD-RFP-LBT with high purity was finally obtained.The fusion protein RGD-RFP-LBT was successfully synthesized by electrophoresis and mass spectrometry.In chapter three,the preparation and characterization of dual-mode imaging probe RGD-RFP-LBT-Gd.Gd3+was chelated with the fusion protein RGD-RFP-LBT by ion concentration difference to obtain the imaging probe RGD-RFP-LBT-Gd,and the spectrum,fluorescence stability and targeting properties of RGD-RFP-LBT-Gd were verified.The results showed that RGD-RFP-LBT-Gd had stable fluorescence emission in a wide pH environment and stable fluorescence property in lysosomal environment,tumor microenvironment and normal body fluid environment for 7 days,which proved that RGD-RFP-LBT-Gd had better fluorescence stability.The high affinity of RGD-RFP-LBT-Gd to integrin αvβ3 was verified by cell experiments.In chapter four,the biological toxicity and dual-mode imaging of RGD-RFP-LBT-Gd.According to the results of MTT test,weight of mice,hemolysis rate,blood biochemical indexes and organ tissue sections,RGD-RFP-LBT-Gd has good biocompatibility.When RGD-RFP-LBT-Gd was injected into U87MG tumor bearing mice by tail vein for 4 h,obvious fluorescence/magnetic resonance signals were observed in the tumor site.In chapter five,we summarize and prospect the work of this paper.The protein-based fluorescent/magnetic resonance imaging probes developed can be used to accurately target tumors and enrich the variety of imaging probes.This biosynthesis strategy provides a new idea for the design and development of protein-based multimodal imaging probes.