title: Cu-Based Metal-Organic Frameworks as a Catalyst To Construct a Ratiometric Electrochemical Aptasensor for Sensitive Lipopolysaccharide Detection.
abstract: In this work, we developed a sensitive and efficient ratiometric electrochemical method for lipopolysaccharide (LPS) detection using Cu-based metal-organic frameworks (Cu-MOFs) as a catalyst and target-triggered quadratic cycles for signal amplification. First, in the presence of target LPS, the conformation change of the specifically designed hairpin probes 1 (HP1) triggered the target cyclic-induced polymerization to produce the output DNA with the aid of phi29 DNA polymerase (phi29). Then, the obtained output DNA hybridized with ferrocene-labeled hairpin probes 2 (Fc-HP2, which were immobilized on the electrode) to generate a nicking endonuclease (N.BstNBI) cleavage site. Thus, with N.BstNBI, the original signal molecules of Fc left from the electrode, and the single-stranded capture-probe-modified sensing interface was obtained. At this time, signal probes conducted by Au-nanoparticles-functionalized Cu-MOFs and labeled hairpin probes 3 (HP3/AuNPs/Cu-MOFs) were hybridized with capture probes for hairpin assembly. Herein, AuNPs/Cu-MOFs were not only used as nanocarriers for immobilizing HP3 but also acted as electroactive materials for signal reporting. With the proposed target-triggered quadratic cycles, the cleavage sites of Fc-HP2 were cut, and capture probes were obtained to hybridize with HP3/AuNPs/Cu-MOFs, which caused the signal decrease of Fc. Then Cu-MOFs were closed to the electrode for the signal increase of Cu-MOFs. Furthermore, when glucose was present in the detection solution, AuNPs/Cu-MOFs catalyzed the oxidation of glucose to realize the enzyme-free signal amplification. By measuring the peak currents ratio of the Cu-MOFs and Fc, the proposed aptasenor for LPS detection showed a low detection limit (0.33 fg/mL) and a wide linear range from 1.0 fg/mL to 100 ng/mL with high accuracy and sensitivity. This ratiometric electrochemical approach is expected to be a valuable strategy for detection of other analytes.
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, China.
authors.forename: Wen-Jun
authors.initials: WJ
authors.lastname: Shen
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhuo
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, China.
authors.forename: Ya-Qin
authors.initials: YQ
authors.lastname: Chai
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, China.
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D055664:Electrochemical Techniques; D006834:Hydrazines / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000032:analysis*; D009942:Organometallic Compounds / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D052157:Aptamers, Nucleotide; D006834:Hydrazines; D008070:Lipopolysaccharides; D009942:Organometallic Compounds; D003300:Copper