title: In situ generation of self-enhanced luminophore by β-lactamase catalysis for highly sensitive electrochemiluminescent aptasensor.
abstract: This work described a new electrogenerated chemiluminescence (ECL) aptasensor for ultrasensitive detection of thrombin (TB) based on the in situ generating self-enhanced luminophore by β-lactamase catalysis for signal amplification. Briefly, a ruthenium complex (Ru-Amp), including two regions of [Ru(phen)2(cpaphen)](2+) and ampicillin (Amp), was synthesized as a self-enhanced ECL luminophore, which can produce an ECL signal through intramolecular interactions. Then, carbon nanotubes (CNTs) were used for immobilization of Ru-Amp via π-π stacking interactions to form the Ru-Amp@CNTs nanocomposite. Using poly(ethylenimine) (PEI) as a linkage reagent, Au nanocages (AuNCs), owing to their electronic property and large surface areas, were decorated to the CNTs to form the Ru-Amp@CNTs-PEI-AuNCs nanocomposites, which were further used to immobilize thrombin binding aptamer II (TBA II) to form a signal probe (Ru-Amp@CNTs-PEI-AuNCs-TBA II). Through "sandwich" tactics, TBA II bioconjugates, TB and TBA I were immobilized onto the gold nanoparticles modified electrode. Then, with the enzyme catalysis of β-lactamase, a novel self-enhanced ECL luminophore (Ru-AmpA) was in situ produced, which could exhibit a significant enhancement of ECL signal, due to the structure transformation of an amide bond into a secondary amine. A sandwich ECL assay for TB detection was developed with excellent sensitivity of a concentration variation from 1.0 fM to 1.0 pM and a detection limit of 0.33 fM. Therefore, the self-enhanced ECL luminophore, combining the further enhancement by in situ enzymatic reaction, is expected to have potential applications in biotechnology and clinical diagnosis.
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, China.
authors.forename: Guo-Feng
authors.initials: GF
authors.lastname: Gui
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhuo
authors.forename: Ya-Qin
authors.initials: YQ
authors.lastname: Chai
authors.forename: Yun
authors.initials: Y
authors.lastname: Xiang
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
mesh_terms: D015374:Biosensing Techniques; D002384:Catalysis; D049449:Luminescence; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases