Construction And Application Of 3-D DNA Nanoparticles And Ratio-type Fluorescent Nanoparticles Probes Based On Lanthanide Metal Coordination Polymer

In recent years,with the increasing requirements for biomolecule detection in various fields,the construction of simple,sensitive,convenient and specific strategies for the research of biomolecules has become one of the focus of researching in many fields.As we all know,the development of convenient,sensitive and specific detection methods for residual antibiotics in food is beneficial to ensure food quality and human health.At present,the arduous challenge of developing a sensitive,quantitative and portable on-site antibiotic detection strategy is the lack of simple and effective target recognition,signal amplification strategies and direct digital quantification techniques.In recent years,3-D DNA nanodevices has received more and more attention because 3-D DNA nanodevices are not limited to traditional 1D and 2D spaces and have precise regulation.Importantly,3-D DNA nanodevices has further solved the problem of insufficient loading capacity to realize signal amplification strategies.In this paper,we developed a visual digital aptamer sensor based on the signal probe induced by the binding of 3-D DNA nanodevices for simple,sensitive and immediate detection of food residue antibiotics.Amyloid?-peptide(A?)in blood is an important biomarker and therapeutic target for early diagnosis of Alzheimer's disease(AD),thus it has attracted widespread attention in AD's detection and monitor.Due to the low concentration and high interference from environmental or background factors,it is difficult and challenging to monitor the subtle changes of A?in the blood.Recently,lanthanide metal coordination polymers(LCPNPs)have been favored due to their unique luminescence characteristics and high sensitivity.In this paper,we constructed a ratio sensor based on a luminescent lanthanide metal coordination polymer(luminol-Tb-GMP-Cu)as a fluorescent probe for simple,sensitive and accurate detection of A?.In this paper,we constructed new signal amplification platforms to realize the quantitative analysis of antibiotics and A?based on glucose meter(PGM)and fluorescence detection method,respectively.The main contents include:1.3-D DNA nanodevices for on-site sensitive detection of antibiotic residues in foodIn this work,we have constructed a visual digital quantitative aptamer sensor based on 3D DNA nanodevice for sensitive and on-site detection of antibiotics.In this sensor,first,we designed a bifunctional aptamer hairpin probe.When the target antibiotic(kanamycin is a model)is present,the bifunctional aptamer hairpin structure is opened,resulting in the antibiotic-aptamer binds and exposing the DNA trigger for catalyzed hairpin assembly(CHA)reaction.Then,the exposed DNA trigger hybridizes with the hairpin probe HP1,resulting in HP1 sequence unfolded.Subsequently,the unfolded HP1sequence hybridizes with the toehold of invertase-HP2 probe and initiates the CHA reaction,forming the MB-HP1-invertase-HP2 complex(3-D DNA nanodevice probe).Finally,the 3-D DNA nanodevice probe catalytically hydrolyzes sucrose in multiple cycles,producing a large amount of glucose for PGM readout.The PGM signal is in proportion of antibiotics concentration.Given that the characteristic of sensitive,fast and quantitative on site,the visual digital quantitative aptamer sensor has shown great potential in food safety.2.Efficient Ratiometric Fluorescence Probe Based on Dual-Emission Luminescent Lanthanide Coordination Polymer for Amyloid?Peptide detectionAs an important biomarker for early Alzheimer's disease(AD)diagnostics and a valuable therapeutic target,amyloid?peptide(A?)in blood has attracted extensive attention concerning its detection and monitoring.The tough challenges for monitoring subtle changes of A?in blood are low expression and high interference from environmental factors.Here,we constructed a ratiometric sensor based on luminescent lanthanide coordination polymer(luminol-Tb-GMP-Cu)as fluorescence probe for simple,sensitive and accurate detection of A?.The luminescent lanthanide coordination polymer nanoparticles(LCPNPs)fluorescent probe was composed of terbium ion(Tb³⁺)as the center metal ions,cupric ion(Cu²⁺)as a cofactor for Tb³⁺fluorescence silence,guanine monophosphate(GMP)as a bridging ligand that can sensitize the fluorescence of Tb³⁺,and luminol as an auxiliary ligand.In the LCPNPs fluorescent probe,the fluorescence of the GMP-Tb as the response moiety is very weak because the existence of cofactor Cu²⁺prevents the intramolecular energy transfer between GMP and Tb³⁺and results in the quench of GMP-Tb fluorescence.The fluorescence of luminol acts as inner reference.In the presence of A?,the high binding affinity of A?for Cu²⁺causes a remarkable emission enhancement of GMP-Tb and suppresses the quenching effect.However,the fluorescence emission of luminol remains constant as inner reference.Hence,sensitive and accurate determination of A?were performed by the ratio of the fluorescence of luminol(F₄₃₀)to the Tb³⁺(F₅₄₇).With this ratiometric probe,A?was determined with sensitivity down to 20p M.Moreover,the ratiometric probe was also successfully used to the time-gated detection of A?in human plasma with satisfactory results due to its capability to eliminate auto-fluorescence.Significantly,the ratiometric probe can use for visual detection of A?,which validates the potential on-site application.Therefore,this ratiometric sensor with the advantages of great sensitivity,simply and accuracy,provides an outstanding prospect for AD's early diagnosis and treatment.