| Malignant tumors are becoming more and more serious threats to human life and health,and both the morbidity and mortality have shown an upward trend year by year.Therefore,the screening and early diagnosis of malignant tumors are of great significance in guiding clinical precision treatment,monitoring and improving prognosis.Exosomes are vesicles derived from cells,the size is nanometer level,but contains a large number of biologically active substances,including proteins,nucleic acids and lipids,which play an important role in the occurrence and development of tumors.There are a variety of mi RNAs(Exo-mi R)in exosomes.Exo-mi R,as a kind of biological molecule with rich genetic information,is closely related to the occurrence and prognosis of lung cancer,breast cancer,ovarian cancer,prostate cancer and other malignant tumors with high mortality,as well as colorectal cancer,liver cancer,pancreatic cancer,cholangiocarcinoma and other common clinical tumors.Recent studies have shown that exo Mir is of great significance in the early diagnosis,clinical classification and prognosis evaluation of tumors,and it is a kind of potential tumor molecular markers.Due to the low content of Exo-mi R derived from cells and the interference of various complex matrices,the establishment of a sensitive,specific and rapid detection method is still an important topic in the basic research and clinical application of Exo-mi R.In this study,we designed and constructed an electrochemical(e TDN)sensor based on tetrahedral DNA nanostructure labeling for ultra-sensitive detection of Exo-mi Rs.By using the "pre-test assembly" strategy,compared to surface-based hybridization,the target Exo-mi R and self-assembled TDN probe have high-efficiency recognition ability in a homogeneous solution.The TDN-mi R complex can be further specifically bridged through the base stacking effect to form a stable sandwich structure with surface-limited capture sequences.The negatively charged structure in the composite can adsorb the electroactive molecule Ru Hex,and the redox charge generated by Ru Hex can quantitatively reflect the amount of nucleic acid adsorbed on the electrode surface,thereby realizing quantitative electrochemical detection.The inherent pressure of TDN can adsorb a large number of electroactive molecules by stoichiometry,thereby greatly improving detection sensitivity,especially by using electron-neutral peptide nucleic acids instead of DNA probes to minimize background signals.The constructed e TDN sensor has high sensitivity(34 a M)and good specificity.It can also be used for non-binding and non-enzymatic detection of Exo-mi R in blood.Preliminary clinical applications have shown that the content of Exo-mi R21 in the blood of breast cancer patients is significantly higher than that in healthy controls. |
