Design Of Novel Optical Sensing Ensemble Based On DNA/carbon Nanomaterials Assembly

Carbon nanomaterial is praised as one of the most important nanomaterials in the21st century. Due to the outstanding properties in electromagnetism, mechanics, opticsand thermodynamics, it shows tantalizing application prospect in many areas such aschemistry, material science, physics and biology. It provokes strong reactions inscience and gradually becomes the scrambling focus of the researchers.One important direction of analytical chemistry is to design sensors which arecapable of generating measuring signals with regard to specific target analyses. Withthe advantages of high sensitivity, good selectivity and convenience of use, etc.,fluorescent sensors have been made great progress in recent years. Through combiningcarbon nanomaterials with nucleic acid probes, the development of DNA/carbonnanomaterials-based fluorescent sensors has become the heated area in recent study.However, according to the previous reports, since the interaction between carbonnanomaterials and ssDNA is very strong, the fluorescence recovery efficiency is lowand the dynamic response is slow. Therefore, the performance enhancement of theDNA/carbon nanomaterials-based fluorescent sensors should be explored andimproved in the construction of fluorescent sensors. The purpose of this thesis is tofurther discuss the construction of the DNA/carbon nanomaterials-based fluorescenesensing platforms based on our studies in the field of fluorescent sensing. and torealize the high sensitive and high selective fluorescence detection of nucleic acid,protein, metallic ion and intracellular miRNA. It mainly focuses on the following threeworks:（1） Design of efficient DNA/SWNTs bio-sensing ensemble based on thecompetitive assembly of a short complementary DNA （scDNA）. The introduction of aspecial series of scDNA can change the DNA structure adsorbed on the carbonnanomaterials surface, and reduce the affinity force between DNA and carbonnanomaterials, making it hybridize with the target more effectively, thus improving itsassociation rate. Moreover, the released scDNA can increase the fluorescence recoveryability of the probes through its competitive assembly on the carbon nanomaterialssurface, thus successfully improving the properties of the DNA/carbonnanomaterials-based sensing ensemble. Rapid fluorescence response with highsensitivity and high selectivity towards nucleic acid, protein and intracellular miRNAhas been realized by making use of the strategy. （2） Design of efficient DNA/GO sensing ensemble based on the controllableself-assembly of aptamer. The designed DNA structure can weaken the affinitybetween aptamer sequence and GO, increasing the binding efficiency toward the target.Moreover, the released short complementary DNA can be adsorbed on the GO’ssurface competitive assembly and therefore enhances the fluorescence recoveryefficiency of sensors. It successfully improves the properties of DNA/GO-basedsensing ensemble, and realizes the high sensitive and high selective fluorescencedetection of PDGF through this strategy.（3） Design of novel Hg²⁺fluorescent sensor ensemble based on DNA/carbonnanoparticles complexes. The preparation of carbon nanoparticles in this work issimple and it has high quenching efficiency toward fluorescence dye. Compared withother carbon nanomaterials, e.g. SWNTs and graphene. carbon nanoparticles’ affinityforce toward DNA is relatively weaker, thus DNA/carbon nanoparticle-based sensingensemble can be improved successfully, thereby realizing the sensitive and selectivefluorescence detection of Hg²⁺. Based on this strategy, we can design other excellentfluorescent sensing ensemble for detection of heavy metal ions.