Study On Functional Nucleic Acid Nanomaterial-Based Biosensor For Biomarkers Of Breast Cancer Disease

Breast cancer is one of the most common malignant tumors in women.Its etiology and pathogenesis are complex,and most early breast cancers have no obvious symptoms.Therefore,it is of great significance to accurately diagnose early breast cancer by detecting biomarkers.At present,the commonly used immunoassay methods have the common shortcoming-s of detection limit,complex method and expensive instrument,while biosensor is simple to build and rapid detection,so it has been widely developed and applied.Nanomaterials have been widely studied and applied in the field of biosensing due to their excellent physical and chemical properties and good biocompatibility.In this paper,two biosensors were constructed based on the nanomaterial properties of Prussian blue and gold nanoparticles to achieve accurate detection of breast cancer biomarkers.（1）Firstly,we constructed an aptamer sensor based on the adsorption capacity of Prussian blue nanoparticles（PBNPs）for Apt and the peroxise-like enzyme（POD）activity of PBNPs,and successfully realized the sensitive detection of HER2.Studies show that when Apt is adsorbed on PBNPs,the POD-like catalytic activity of Apt@PBNPs complex is significantly enhanced compared with bare PBNPs,and it can catalyze the oxidation of TMB by H₂O₂ to produce blue product ox TMB,which has an obvious ultraviolet absorption peak at 652 nm.When HER2 exists in the system,Apt specifically binds with HER2 to form Apt-HER2 complex,which is far away from the surface of PBNPs,weakening the pod-like activity and UV absorbance of the system.The concentration of HER2 in the system was accurately quantified by the change of UV absorption intensity before and after the presence of HER2.The linear range was 1-6ng·m L^-1,and the detection limit was 0.5 ng·m L^-1.The sensor is simple,convenient and highly selective.（2）Considering that individual detection of biomarkers may lead to false negative/positive results,we designed a composite probe fluorescence sensor based on three-dimensional（3D）DNA nanowalkers to achieve multiple detection of HER2 and miRNA-21.When HER2 is present in the system,HER2 specifically binds with Apt,leading to the release of walking chain（h DW）.Driven autonomously by endonuclide（Nb.Bbvc I）,h DW can walk on AuNPs surface,leading to the separation of all FAM-labeled f HD fragments from AuNPs surface.The fluorescent signal was restored.Similarly,the presence of miRNA-21 triggers a toehold mediated chain replacement reaction（TMSDR）,releasing the walking chain（m DW）,which can walk autonomously on AuNPs surfaces,leading to the separation of all cHD fragments with Cy5 fluorescence labeling from AuNPs.Due to the signal amplification of the 3D DNA walker,the composite probe achieves multi-sensitive detection of HER2and miRNA-21.The detection range of HER2 was 0.5-5 ng·m L^-1,and the detection limit was as low as 0.03 ng·m L^-1.The detection range of miRNA-21 was 0.1-7 p M,and the detection limit was as low as 0.02 p M.This sensor has certain application value in the analysis and detection of biomarkers of early breast cancer.