Research And Application Of Electrochemical Biosensor Based On G-quadruplex Dnazyme-catalyzed Deposition Of Polyaniline

In recent years, more attention has been given to polyaniline (PANI) based on itsremarkable electrical, electrochemical and redox properties as well as goodenvironmental stability. HRP-mimicking DNAzyme could efficiently catalyzeoxidation polymerization of aniline to PANI in the presence of H2O2with theadvantages of the higher control over the kinetics of the reaction and the highefficiency of the enzyme catalyst. Heavy metal ion exhibits serious adverse effect onhuman health, which is of high toxicity, chronicity and accumulation. In addition,identification and determination of specific nucleic acid sequences is beingtremendously motivated by its spacious applications in genetics therapy, clinicaldiagnosis and a variety of biomedical studies. Therefore, construction ofelectrochemical biosensor based on G-quadruplex DNAzyme-catalyzed template-guided deposition of polyaniline pave a new way for reliable and rapid detection ofthese analytes.There are three chapters in the thesis:1. The first chapter systematically introduces the biosensor component and somenano-materials, mainly including: the definition, classification, principle, characteristic,manufacture and application; G-quadruplex DNAzyme can simulate horseradishperoxidase, which could be widely used in biosensor constructed; the main properties,preparation and application of gold nanoparticles; the application of conductivepolymers, especially polyaniline, in the biological sensing.2. A novel, simple, and versatile amperometric sensing platform was developedbased on HRP-mimicking DNAzyme-catalyzed template-guided deposition ofpolyaniline. Pb2+was chosen as a model to demonstrate the proof-of-concept of ourapproach. The constructed platform exhibited a good linear response toward Pb2+overa wide range of concentration from1.0nM to1.0μM with the detection limit of5.0×10–10M. The high performance DNAzyme-based strategy can be further extended to quantify a wide variety of analytes.3. A novel and versatile amplified electrochemical strategy for ultrasensitivedetection of nucleic acid has been developed on the basis of polyaniline as the redoxlabel which was guided and deposited by multiple HRP-mimicking DNAzyme as apowerful catalyst and template generated by bio-bar codes-initiated rolling circleamplification (RCA). As a result of multiple amplification effects, the constructedplatform exhibited a good linear response toward nucleic acid over a wide range ofconcentration from6.0fM to1.0nM.