Novel Shear Wave Elastography Probes For Precise Diagnosing Tumor Microenvironment Research

Compared to normal cells,the abnormally metabolic activity of tumor cells leads to the unique redox characteristic of tumor microenvironment（TME）,which is closely related to the development,invasion and metastasis of tumor.Therefore,accurate detection of TME by imaging is of great importance.Shear wave elastography（SWE）provides the critical information of tissue stiffness and has shown great clinical application in detecting tumor,liver fibrosis and myocardial function.However,ultrasound microbubble contrast agents currently used are not suitable for SWE imaging due to their inability to propagate shear wave.Focused on the precise diagnosis of TME by SWE,two types of intelligent SWE imaging nanoprobes are designed and prepared in this paper.The probes are used to detect the apoptotic enzyme Caspase3and the calcium ions in the TME respectively.The main research contents are as follows:1.A novel SWE contrast agent for the accurate diagnosis of hepatoma:SWE is a novel ultrasound functional imaging technique that uses shear waves to quantify the elastic modulus of tissues.However,it is difficult to distinguish tissues with similar elastic modulus by SWE.For example,focal hepatopathies caused by chemotherapy produce false-positive diagnoses because of the similar pathological features to liver metastases.Here,a strategy of modulating the strength of chemical bond to alter the elastic modulus is proposed for the precise diagnosis of hepatoma.Ac-Asp-Glu-Val-Asp-Cys（St Bu）-Lys（Fe₃O₄）-CBT（Fe₃O₄@1）nanoparticles are designed and synthesized for accurate SWE imaging diagnosis of hepatoma.The specific reaction of Fe₃O₄@1 with overexpressed glutathione（GSH）and apoptotic enzyme（Caspase3）in liver cancer lead to a condensation reaction between cyanobenzothiazole（CBT）and cysteine to form covalently bonded crosslinks,which results in a significant enhancement in the elastic modulus of tumor.The experimental results in aqueous solution,Huh7 cells,tumor-bearing model mice and hepatoma model mice show that Fe₃O₄@1 can significantly enhance the elastic modulus difference in the target region,exhibiting a significant SWE contrast performance.It is worth mentioning that the elastic modulus signals difference increases up to about 5.0-fold after Fe₃O₄@1specifically responds to the Caspase3 in hepatoma.In conclusion,the innovative strategy based on modulating the chemical bond strength to alter the elastic modulus proposed in this work will provide a reference research idea for exploring new ultrasound contrast agents and is expected to expand the application of SWE for the accurate detection of TME.2.A novel SWE contrast agent for monitoring the calcium ion stability imbalance in tumor:Ion interference therapy（IIT）is a novel technique for tumor treatment,which mainly disturb the functional ions in tumor to cause the death of tumor cells.However,it is still not possible to visualiz this process.Therefore,sodium alginate is utilized to chelate the Ca²⁺in tumor,leading to the production of hydrogel and the significant change in the elastic modulus,which can be monitored by SWE imaging.The injectable sodium alginate can cause the imbalance of Ca²⁺stability and reverse the distribution state of Ca²⁺to achieve an efficient tumor therapy.Meanwhile,sodium alginate can generate calcium alginate hydrogel to change the elastic modulus in tumor,which can be sensitively monitored by SWE.The experimental results of aqueous solution confirm that SWE can dynamically monitor sodium alginate chelation of Ca²⁺at various concentrations（2,3,4,and 5 m M）,and the SWE signal increases from 124.3d B to 185.8 d B.In addition,the experimental results show that sodium alginate can interfere with the Ca²⁺stability in tumor cells,further leading to the death of tumor cells.Compared to the control group,the SWE signal of tumor tissue increases significantly after injecting sodium alginate within 120 s and reaches to 128.5 d B after5 days,which is approximately 10.1 times higher than before.This work is capable of monitoring the therapeutic process of tumor with Ca²⁺interference by SWE,which provides a reference research method for the integration of IIT in treatment and diagnosis.