The Research Of Self-Assemble Probe Design Based On The Spiropyran Derivatives, Carbon Nanotubes And Nucleic Acid

In recent years, the combination and development of functional molecule and nanomaterials have been one of the most important branch directions of analytical chemistry which is based on the specific recognition, at the same time, the chemical/biology sensing has attracted more and more attentions in the fields of environment, biology, medicine and so on. Among them, the nucleic acid molecules and small organic molecules that possess a high specific recognition to the target have provided many ideas and strategies for the design of the new probe. Through rational design and screening, the researchers have acquired numbers of functional DNA molecules that correspond with the different kinds of targets, such as:molecular beacon, DNAzyme, moreover, the corresponding of functional DNA molecules and low-dimensional carbon nanomaterials could reduce the background signal, promote the signal conversion, and amplify the signal. Because of its high detection sensitivity, good selectivity and convenient use, the organic small molecule probe has become a powerful tool for the design of new biological chemical sensor, the sensing strategy when using the small organic molecules to assay the target was main factor that affected the sensing performance of organic porbe, so, it is meaningful to research and develop controllable, high sensitivity and selectivity small organic probes. The combination of organic molecules and nanomaterials could improve the ability of recognition, produce and amplify the detection signal, and be helpful for analytical methods and detection system to the application in the disease diagnosis.However, in the present research, many disadvantages exist such as:the relatively low fluorescence signal, the low ability to resist photobleaching, the complexity in the designing of DNA probe and a strong interference of biological background. To solve the above problem, this paper focus on the non-covalent interaction between organic small molecule probe and low-dimensional carbon nanomaterials, regulation and control of cyclodextrin molecule channel closure by DNA molecular recognition, the controllable electrochemical probe of organic molecules and the construction of logic gates based on the functional DNA probe. As there is a strong π-π conjugate interaction between the SWCNTs and small organic molecules, we could fix the organic probe on the surface of the electrode by SWCNTs, and utilize the recognition event between organic probe and the target to produce the chemical group that possess the electrochemical activity. Furthermore, by introduce the so called photochromic compounds-spiropyran to the organic probe, we have designed the controllable electrochemical sensor. We know that some specific assay targets could change the structure and the hybrid state of DNA probes, and then affect the fluorescence properties, based on these characteristics, we have realized the switch of multiple DNA logic gates. The main works are follows:(1)The construction of new type F-selective electrode based on the interaction between F-and Si-O bonds. The research results shown that the Si-O bonds could be cleavage after interact with the F-, so we have designed a spiropyran derivatives probe-SPS, whose Si-O bonds could be cleavage after interact with the F-, then produce a phenol oxygen anion. As the SPS in polar solvent could occur isomerization from the ring closed spiropyran to the ring opened merocyanine and resulted in the produce of hydroquinone, a reversible redox peaks were observed under the CV scan. In this way, we have realized the quick detection from water and urine.(2) In this system, we take the adenine for guanine substitution (A→G) at nucleotide position (np)8344of mitochondria gene mutations as an example and propose a strategy for the detection of DNA polymorphism based on RNase HⅡ-amplified non-modification in situ DNA metallization and sharp solid-state electrochemical techniques of AgNPs. The DPV signal of Ag/AgCl solid-state electrochemistry was found to be specific for the amount of DNA template. The unique electrochemistry of in situ synthesized AgNPs was then utilized to develop a biosensing strategy to determine DNA polymorphism with the assistance of RNase HII, to hydrolyze dsDNA and liberate signal probe. The method has a linear range of10pM-10nM and a low detection limit of5pM. The proposed method may be extended to a wide variety of DNA polymorphism affected diseases-related biosensing.(3) Development of spiropyran-based electrochemical sensor via simultaneous photochemical and target-activatable electron transfer. A new spiropyran probe (SP-β-gal) substituted by galactose in6-position via glycosidic bond was designed, the glycisidic bond of SP-β-gal could be hydrolyzed by P-galactosidase to get a phenolic oxygen anion in6-position, but no electrochemical signal response can be observed, after simultaneous UV irradiation, the hydroquinone would appear to produce a reversible redox peaks.(4) Design of multiplex logic gates by combining regulation of DNA structure with logical calculation. Multistep FRET among FAM, ALEXA and TAMRA are utilized to regulate the fluorescence emission intensities, the Pb2+-DNAzyme and T-rich probe could response to the Pb2+and Hg2+to produce output signal, the three logic gate could be easy to control by just change the excited wavelength and observed wavelength.