The Biosensor Based On Graphene As A Carrier For Detection Of Apoptosis And Small Molecules

The main content of this paper is based on a new nanometer material grapHene, With the help of single molecules and grapHene monolayer characteristics as carrier and protective agent DNA biosensor, and using DNA hybridization, DNA replication cycle combination, we developed a new type of biosensor with high sensitivity, high selectivity, for specific biological molecules such as theopHylline, thiamine pyropHospHate selective recognition and measurement, and can be for many diseases and provide a theoretical basis for clinical early diagnosis, detection of apoptosis acidification.1. The first chapter, mainly introduces the development and research of grapHene discovery, synthesis method and application of cutting-edge. The discovery of grapHene has the extremely vital significance, may be a new material to change the world. Then the paper provides a brief overview of the introduction and the role of the composition and the classification, DNA endonuclease and a brief introduction of the polyacrylamide gel electropHoretic analysis, confocal microscopy and fluorescence chemical analysis method. To explaine transcription of DNA, and ribozyme (RNA).2. The second chapter, with changes in the solution of PH as the driving force, through the acidity changes to drive change between the double helix and three helical state molecular machines. When the pH value of solution reaction system is basic, DNA nano machine performance for the double helix state, Rhodamine Green, BHQ located at both ends of long chain DNA, the two do not close can be detected by fluorescence. When close to the reaction system for the transformation of acidic solution of DNA nano machines for the three spiral Rhodamine Green and BHQ, the fluorescence is quenched, signal low. Continue adding alkali, acid can be continuously cycle.To construct a DNA sensor with PH changes as power. 3. The third chapter, A duplex-triplex switchable DNA nanomachine was fabricated and has been applied for the demonstration of intracellular acidification and apoptosis of Ramos cells, with grapHene oxide (GO) not only as transporter but also as fluorescence quencher. The machine constructed with triplex forming oligonucleotide (TFO) exhibited duplex-triplex transition at different pH conditions. By virtue of the remarkable difference in affinity of GO with single-stranded DNA (ssDNA) and triplex DNA and the super fluorescence quenching efficiency of GO, the nanomachine functions as a pH sensor based on fluorescence resonance energy transfer (FRET). Moreover, taking advantage of the excellent transporter property of GO, the duplex-triplex/GO nanomachine was used to sense pH changes inside Ramos cell during apoptosis. Fluorescence images showed different results between living and apoptotic cells, illustrating the potential of DNA scaffolds responsive to more complex pH triggers in living systems.4. The forth chapter, A structure-switching-based approach for the design of fluorescent biosensors from known RNA aptazymes were demonstrated for the detection of theopHylline and TPP. Taking advantages of the ability of grapHene oxide (GO) to protect ssDNA from nuclease cleavage and the cyclic amplificaiton induced by deoxyribonuclease I (DNase I), the assay was highly sensitive amplified. In the absence or presence of target, the target-dependent hammerhead aptazyme cleaves off. The released SD sequence was introduced into the detection system, in which a FAM labeled probe ssDNA was noncovalently assembled on GO, and the fluorescence of the dye was completely quenched. In the presence of the released sequence, the binding between the dye-labeled DNA and the SD sequence alter the conformation of dye-labeled DNA, and disturb the interaction between the dye-labeled DNA and GO, liberating dye-labeled DNA from GO. The fluorescent intensity was increased, whereupon the DNase I can cleave the free DNA in the DNA/RNA complex, thereby liberating the fluoropHore and ultimately releasing the SD RNA sequence. The released SD RNA sequence then binds another DNA probe, and the cycle starts anew, which leads to significant amplification of the fluorescent signal. The approach opens up a wide range of possibilities for sensing of other small molecules in biological entities.5. The fifth chapter, The main content of this thesis is based on the new nano material grapHene as a foundation, and in accordance with the characteristics of single molecule and single layer of grapHene as a carrier of the DNA biosensor and protective agent, and with the help of a DNA molecule hybridization technique, combining the circular DNA replication, developed the high sensitivity, high selectivity new biosensors...