The Research On Biosensor Based On New SNA Nanoassembly And HCR

Nucleic acids based reagents represent an essential tool in detection and regulation of gene expression and protein activity for chemistry and biology. Efficient approaches for intracellular delivery of nucleic acid reagents to achieve sensitive detection and regulation of gene and protein expressions are essential for chemistry and biology. Recent advance in nanotechnology has fueled the development of nanoscale nucleic acids assemblies for intracellular applications.Notably, spherical nucleic acids (SNA) have been extensively explored,such as:intracellular detection and gene regulation. Nevertheless, current nucleic acid nanostructures typically exhibit limited sensitivity for intracellular detection and regulation with a detection limit at the nanomolar level. This shortcoming is largely due to the lack of signal amplification mechanisms in these methods. A viable embodiment of signal amplification strategies that are able to be realized in living cells using a specific nucleic acids nanoassembly, therefore, remains an unresolved challenge. In this thesis, we develop a novel SNA nanoassembly, then on this basis,HCR is also utilized to enables ultrasensitive fluorescence activation imaging of mRNA expression with a picomolar detection limit:(1)We develop a novel SNA nanoassembly. The DNA nanoassembly has a designed structure with a core gold nanoparticle, a cationic peptide interlayer and an electrostatically assembled outer layer of hairpin DNA probes. It is shown to have high efficiency for cellular delivery of DNA probes via a unique endocytosis-independent mechanism that confers a significant advantage of overcoming endosomal entrapment.(2)Electrostatic assembly of DNA probes enables target-initialized release of the probes from the nanoassembly via HCR. This intracellular HCR offers efficient signal amplification and enables ultrasensitive fluorescence activation imaging of mRNA expression with a picomolar detection limit. The results imply that the developed nanoassembly may provide an invaluable platform in low-abundance biomarker discovery and regulation for cell biology and theranostics.