| The early detection and diagnosis of tumors is critical to their prevention and treatment.Studies have shown that early detection and timely treatment can significantly improve the cure rate of tumors.The early diagnosis of tumors mainly involves the detection of tumor tissue,serum,and peripheral blood,including tumor markers in various biomolecules,such as DNA,m RNA,metabolites,transfer factors,cell surface receptors,and even whole cells.Biosensing technology is characterized by real-time,simplicity and speed.Among the numerous nano-biomaterials,DNA-AuNPs are particularly widely used in biological diagnostics and nano-architecture due to their excellent physical and chemical properties,such as unique optical properties,excellent electrical and cata lytic prope rties,and good biocom patibility.In order to impr-ove the dete ction rate and dete ction sensitivity of tumor markers,a biosensor based on diblock DNA-AuNPs was constructed to achieve highly sensitive detection of tumor markers in this study.The specific work carried out is as follows:1.Based on the diblock DNA-AuNPs probes,a multicolor nanoprobe was prepared for the simultaneous detection of multiple mi RNAs.In order to improve the sensitivity of biosensors,enzyme amplification technology was introduced to signal cycle amplification.At the same time,in order to achieve simultaneous detection of multiple mi RNAs in the system without interfering with each other,we selected different fluorophore for the corresponding DNA probes.It is possible to precisely control the spatial configuration of DNA probes by adjusting the length of polyA,which provide a best-fitting model for DNA hybridization and digestion.The polyA effectively eliminates the non-specific adsorption between the probes and the AuNPs,and thus significantly improves the reaction kinetics compared to the thiolated probes.The detection limit of the mi RNA is lower than 0.05 f M.In addition,assays in serum samples show that the sensor can perform specific target mi RNA detection simultaneously in clinical samples.2.A polyA-mediated fluorescent spherical nucleic acid(FSNA)nanoprobe with controlled surface density was used to detect intracellular c-Myc m RNA.The adjustable length of the polyA tail provides an opportunity to precisely control the orientation and conformation of the probes on the surface of the AuNPs,greatly improving hybridization efficiency and detection sensitivity with a detection limit of 0.31 n M.Compared to thiolated FSNA probes,the sensitivity of polyA-mediated FSNA probes was 55-fold higher.Furthermore,intracellular reactions can be observed more quickly in cells incubated with FSNA,which facilitates efficient and sensitive detection in living cells.In addition,confocal imaging showed that FSNA can effectively distinguish cancer cells from normal cells by detecting differences or changes in m RNA expression in cancer cells.FSNA has great potential for biomedical applications and early clinical diagnosis.3.In order to further expand the application of diblock DNA-AuNPs in the field of biosensing,combined with the strong adsorption of ss DNA by Mo S2,a DNA-AuNPs/Mo S2 probe was constructed to be a visual sensor for detecting PIK3 CA ct DNA.In order to increase the sensitivity of biosensors,enzyme amplification techniques were introduced and signal cycle amplification was performed based on Exo III specific cleavage.By optimizing experimental conditions,the detection limit of ct DNA is as low as 19.78 n M.The colorimetric method used to determine ct DNA is simple and intuitive and has potential applications in medical diagnosis and portable detection. |
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