Research On New Methods Of Photoelectric Signal Amplification And Biological Analysis Based On Functional Nanomaterials

Using modern technologies such as light and electricity to design and build a biosensing detection system is one of the main components of analytical chemistry.Optical and electrical biosensing systems have the advantages of low cost,high sensitivity and easy operation.They mainly detect specific biomolecules and convert them into corresponding readable signals,and finally achieve the purpose of quantitative analysis of biomolecules.The new functionalized nanomaterials have unique optical and electrical properties,and have been used in various fields by virtue of their superior properties such as volume effect,quantum size and surface effect.This work mainly explores new methods of photoelectric signal amplification and biological analysis based on functional nanomaterials,and finally achieves highly sensitive detection of lipopolysaccharide,carcinoembryonic antigen,and thrombin.We have carried out work in three areas:1.A new type of biosensing platform is proposed,which uses multiple amplification strategies to detect lipopolysaccharide?LPS?with two signals:electrochemiluminescence?ECL?and fluorescence?FL?.First,three DNA sequences were released through the specific recognition of aptamer-targets on magnetic beads?MB?.These sequences hybridized with the multifunctional molecular beacon?MMB?,and triggered many two-way polymerization and shear reactions,and generated a large number of a1 fragments after multiple cycles of amplification.Then after introducing a1into the triple helix system,the triple helix structure is opened.In the ECL system,single-stranded S2?rich in G bases?forms a hemin/G-quadruplex complex under the action of hemin,which can effectively quench the ECL signal and detect LPS with the ECL"off"signal.In the FL system,the triple helix structure is opened,resulting in the separation of the fluorescein FAM and quencher BHQ in the S1 chain,thereby realizing the fluorescent"on"signal for LPS analysis.The multi-functional platform can realize the amplified ECL and FL signal changes,used for the sensitive measurement of LPS,which provides an application prospect for clinical diagnosis.2.A new 3D DNA nanosphere was ingeniously designed and fabricated,which was used to combine with multiple enzyme-free amplification strategy to develop a photoelectrochemical?PEC?biosensing platform for ultrasensitive detection of carcinoembryonic antigen?CEA?.The 3D DNA nanostructure was self-assembled by base complementary pairing in a few minutes and rolling circle amplification?RCA?reaction.The intense photocurrent derived from Au NPs/ZnSe QDs can be effectively decreased by 3D DNA nanospheres assembled on the electrode,making photoelectric signal present“off”state.The specific binding of target CEA with its hairpin?HP1?aptamer opens HP1 structure,which initiated multiple enzyme-free strand displacement amplification?SDA?reaction and generated a large number of single strands DNA S1.Then S1 competitively binds to capture DNA on the electrode to release 3D DNA nanospheres,thus the photocurrent signal became“on”state.The sensor achieves highly sensitive analysis of the target CEA and has been successfully used in the analysis of real serum samples.The reported strategy opens a new simple way for PEC biosensor using DNA nanostructure,showing huge potential in clinical application research.3.Based on the photoactive material Bi₂O₃-ZnO and sensitizer CdS quantum dots?QDs?,a new type of ultra-sensitive photoelectrochemical?PEC?sensing platform was prepared by constructing super nanowires for sensitive detection of thrombin.The CdS/ZnO/Bi₂O₃ sensitized structure with good energy level arrangement effectively separates electron-hole and significantly improves the photoelectric conversion efficiency.One-step synthesis of super nanowires through dislocation hybridization can carry a large amount of sensitizer CdS QDs.By combining with Exo-III-assisted multiple amplification process,ultra-sensitive detection of thrombin is achieved.The PEC platform can successfully detect human serum thrombin.The CdS/ZnO/Bi₂O₃sensitized photoelectric biosensing platform using DNA nanowires combined with Exo-III assisted multiple amplification has opened up a new sensitization amplification approach for hypersensitive biosensing and biological analysis.