Research Methods Of Surface Enhanced Raman Scattering Sensor Based On Copper Nanoparticles And Entropy Driven Signal Amplification Technology

Recently,Analytical Chemistry for Life Science,as an interdisciplinary subject of analytical chemistry,clinical medicine,biology,pharmacy and so on,has become one of the hot spots and emphases in many fields.Biomolecules（such as proteins,nucleic acids,lipids,etc.）play a practical guiding role in the research and diagnosis of certain related diseases of the human body,the treatment and prevention of certain diseases,and the design of new drug molecules.Therefore,it is of great significance to develop biosensors with favourable signal reproducibility,reliable selectivity and long-term stability for early disease diagnosis and biomedical research.In this thesis,the strategy of quantitative analysis and detection of telomerase,Mucin1 and Pb²⁺was mainly applied by using a strategy of surface-to-enhanced Raman scattering（SERS）to build a new biosensing method.Surface-enhanced Raman scattering technology has become a fast and non-invasive method for detection of biomolecules due to its single-molecule sensitivity,narrow bandwidth and fingerprint of characteristic molecules.Therefore,we designed a biosensing platform based on SERS nano-probes and nano-magnetic spheres,which realized the accurate,simple and sensitive detection of biomolecules.The main researches are presented as following:1.SERS platform was constructed for quantitative detection of telomerase based on Dopamine functionalized Ag nanoprobes regulated by Cu²⁺.In this chapter,an innovative SERS strategy based on copper-mediated silver/dopamine nanoparticles amplificationhas been developed for sensitive and accurate detection of telomerase activity.In the strategy,the copper oxide nanoparticles（Cu O NPs）-encoded magnetic bead（MB-Cu O NPs）probe as recognition and detection element,upon sensing of the telomerase,the Cu O NPs separated from MB due to telomerase elongation reaction.The separated Cu O NPs are then dissolved by acidolysis into copper（II）ions(Cu²⁺)to prompt monodisperse dopamine-functionalized Ag NPs（D-Ag NPs）served as signal probe into aggregation state.Dopamine-functionalized Ag NPs avoid uncontrollable assembly of Ag NPs,thereby reducing non-specific signals and improving detection accuracy.Due to the transformation of Cu O NP to Cu²⁺with a high amplification effect,which escapes from polymerase chain reaction（PCR）and some DNA amplification techniques,and achieves the limit of detection（LOD）as low as 3 He La cells.This strategy offers a reliable,intuitional,and convenient approach for sensitive and accurate detection of telomerase activity,holding great potential in clinical diagnosis and drug discovery.2.Entropy-driven DNA cycling circuit coupled Au nanostar liquid-liquid self-assembly interface ratio SERS platform for Protein biomarkers detection.In this chapter,we developed a ratiometric SERS platform based on entropy-driven DNA circuits-cooperated liquid-liquid self-assembled Au nanostars interface for robust,accurate and sensitive detection of Mucin 1（MUC1）protein biomarker in clinical samples.In the sensing platform,an aptamer-P1-DNA ds DNA detection probe was tailored for target recognition and transformation.Upon selective binding the target MUC1,the complementary chains of protein aptamers was released as mimic target from the detection probe,and triggered three-chain DNA composite structure-based entropy-driven DNA circuits amplification on magnetic bead.Two Raman signals transformed by DNA circuits,andwere separated and localized on the self-assembled Au nanostars（Au NSs）on the immiscible hexane-water interface.Au NSs possess multiple sharp branches acting as“hot-spots”for the“lightning rod”effect,enhancing local electromagnetic fields and improving the detection sensitivity.Benefiting from the entropy-driven DNA circuits amplification and ratio-dependent liquid phase interfacial SERS platform improving the detection accuracy,the limits of detections as low as 0.1 fg/m L of mucin 1 wasachieved.Significantly,the platform demonstrated high-confidence quantification of the contents of Mucin 1 in human serum,indicating thatthis ratiometric SERS sensing strategy willbecome a sensitive and reliable protein biomarkers quantification method in clinicalapplication and biomedical research.3.A surface-enhanced Raman scattering sensing strategy was constructed based on ag-Au core satellite structure probe to sensitively detect Pb²⁺.In this chapter,we developed a method for detecting Pb²⁺based on SERS sensing platform.In general,the target Pb²⁺is specifically recognized by the double-stranded structure composed of the DNAzyme-substrate,thereby initiating the catalytic cleavage activity of the DNAzyme,leading to the cleavage of the ribonucleotide（r A）on the substrate,thereby releasing Pb²⁺and DNAzyme.At the same time,the released DNAzyme can activate the catalytic hairpin assembly（CHA）reaction to open H1.The opened H1 sequence can trigger the HCR reaction,and then H2 and H3 modified with Cu S NPs at the 5’end are introduced into the reaction system.Subsequently,a long ds DNA polymer modified with Cu S NPs was formed.When Ag⁺is added to the system,a large amount of Cu²⁺is produced in the system due to cation exchange reaction.In the presence of Cu²⁺,4-Mpy modified Au NPs and 4-MBA modified Ag NPs form core satellite structures due to the coordination between Cu²⁺and N and O elements in 4-Mpy and 4-MBA,which will not only change the color of the solution,but also produce a large number of"hot spots".Therefore,the assembled core satellite structure showed strong SERS activity.The biosensor combines CHA assisted target recovery,hybrid chain reaction（HCR）and the high amplification effect of Cu S NP conversion to Cu²⁺.It uses SERS platform to achieve ultra-sensitive detection of Pb²⁺,and the LOD is as low as 6.0 p M.In addition,this method provides a guarantee for the accuracy and reliability of the test results,and has been successfully applied to the quantitative detection of Pb²⁺content in actual environmental samples.This strategy is simple to operate and highly accurate,providing a reliable and convenient method for detecting Pb²⁺content in samples,and is expected to become a promising tool in the environmental field.