title: Photoelectrochemical DNA Biosensor Based on Dual-Signal Amplification Strategy Integrating Inorganic-Organic Nanocomposites Sensitization with λ-Exonuclease-Assisted Target Recycling.
abstract: Sensitive and accurate analysis of DNA is crucial to better understanding of DNA functions and early diagnosis of fatal disease. Herein, an enhanced photoelectrochemical (PEC) DNA biosensor was proposed based on dual-signal amplification via coupling inorganic-organic nanocomposites sensitization with λ-exonuclease (λ-Exo)-assisted target recycling. The short DNA sequence about chronic myelogenous leukemia (CML, type b3a2) was selected as target DNA (tDNA). ZnO nanoplates were deposited with CdS nanocrystals to form ZnO/CdS hetero-nanostructure, and it was used as PEC substrate for immobilizing hairpin DNA (hDNA). CdTe quantum dots (QDs) covalently linked with meso-tetra(4-carboxyphenyl)porphine (TCPP) to form CdTe/TCPP inorganic-organic nanocomposites, which were utilized as sensitization agents labeling at the terminal of probe DNA (pDNA). When the hDNA-modified sensing electrode was incubated with tDNA and λ-Exo, hDNA hybridized with tDNA, and meanwhile it could be recognized and cleaved by λ-Exo, resulting in the release of tDNA. The rest of nonhybridized hDNA would continuously hybridize with the released tDNA, cleave by λ-Exo, and set free the tDNA again. After λ-Exo-assisted tDNA recycling, more amounts of short DNA (sDNA) fragments coming from digestion of hDNA produced on the electrode and hybridized with CdTe/TCPP-labeled pDNA (pDNA-CdTe/TCPP conjugates). In this case, the sensitization of CdTe/TCPP inorganic-organic nanocomposites occurred, which evidently extend the absorption range and strengthened the absorption intensity of light energy, and accordingly the photocurrent signal significantly promoted. Through introducing the dual-signal amplification tactics, the developed PEC assay allowed a low calculated detection limit of 25.6 aM with a wide detection scope from 0.1 fM to 5 pM for sensitive and selective determination of tDNA.
authors.affiliation: Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications , Nanjing 210023, P. R. China.|State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Gao-Chao
authors.identifier: http://orcid.org/0000-0002-4645-3115
authors.initials: GC
authors.lastname: Fan
authors.affiliation: Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications , Nanjing 210023, P. R. China.
authors.forename: Qingming
authors.initials: Q
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Jun-Jie
authors.identifier: http://orcid.org/0000-0002-8201-1285
authors.initials: JJ
authors.lastname: Zhu
mesh_terms: D015374:Biosensing Techniques; D019187:Cadmium Compounds; D004247:DNA; D005092:Exonucleases; D053761:Nanocomposites
chemical_list: D019187:Cadmium Compounds; D004247:DNA; D005092:Exonucleases
keywords: DNA assay; photoelectrochemistry; sensitization; target recycling; λ-exonuclease