Research On Novel Porphyrin-Based Electrochemiluminescent Biosensors And Applications In DNA & Protein Assay

Electrochemiluminescence (ECL), the generation of an opticalsignal triggered by an electrochemical reaction, has become animportant and valuable detection method in biosensor field.Owing to its simple, sensitive and low-cost detection capability for applications,ECL has enormous potential in biological applications including clinical genetic analysis, environment monitoring, and forensic identification.Nucleic acid is indispensable in the process of the lifedevelopment as the carrier of genetic information. In addition, the detection of some certain nucleic acid sequence is important in biomedical analysis and molecular diagnosis. The aptamers which have specific structuresand have capabilityfor specifically binding nucleic acid or protein, play a significant role in the construction of biosensors. This postgraduate dissertation contains the following two partsabout the ECLbiosensors based on nucleic acid and apatamers. A Universal DNA Sensing Strategy Based on the Electrochemiluminescence of Supermolecular Porphyrins NanoclustersA novel porphyrin-based electrochemiluminescence biosensor was developed successfully based on the new luminophore(C6o-ZnTPP),which was synthesized owing to the factthat meta-porphyrin could immobilize on some photoelectric molecules by axialcoordination. With the special stem-loop structure, molecular beacons were widely applied into bio-molecular recognition. When the target DNA in the solution reacted with molecular beacons, the stem-loop structure was opened and exposed the terminal groups labelled such new luminophore, which resulted in apparent changes of ECL signal. The magnitude of changes was directly proportional to the concentration of the target DNA. The corresponding biosensor was successfully applied to detect HAIR target DNA sequence with the limit of 1.0 pML-1, which indicated the ECL detection system possess high sensitivity, stability and selectivity. A Specific Electrochemiluminescent Platform Based on Aptamer Functionalized Quantum dots with Lysozyme and Hemin as Co-triggersA rapid, low cost and sensitive ECL method based on G-quadruplex/hemin hybrids was fabricated to detect lysozyme.13 nm gold nanoparticles (AuNPs) were absorbed on the chitosan membrane to immobilize HS-modified hairpin DNA sequence which consisted of lysozyme aptamer sequence and G-quadruplex sequence. In the presence of both hemin and lysozyme, the hairpin structure could be dissociated and generate hemin/G-quadruplex quenchers that could quench the ECL of QDs via consuming O2 as an ECL endogenous coreactant. This design has showed the linear response ranges and detection limits of 20 pg ml-1～5 μg ml-1.