title: Sensitive and visual detection of sequence-specific DNA-binding protein via a gold nanoparticle-based colorimetric biosensor.
abstract: A novel exonuclease III (Exo III) protection-based colorimetric biosensing strategy was developed for rapid, sensitive, and visual detection of sequence-specific DNA-binding proteins. This strategy relied on the protection of DNA-cross-linked gold nanoparticle (AuNP) aggregates from Exo III-mediated digestion by specific interactions of target proteins with their binding sequences. Interestingly, we disclosed a new finding that binding of target proteins to their binding sequences in the aggregated AuNP network rendered a stable and long-period protection of DNA. Unlike conventional fluorescence assays merely based on temporal protection of DNA from Exo III digestion, the stable protection afforded a static color transition indicator for DNA-protein interactions with no time-dependent monitoring required in the assay. Therefore, it furnished the developed strategy with improved technical robustness and operational convenience. Furthermore, we introduced thioctic acid as a stable anchor for tethering DNA on AuNPs. This DNA-tethering protocol circumvented the interferences from thiol compounds in common enzymatic systems. The Exo III protection-based colorimetric biosensor was demonstrated using a model target of TATA binding protein, a key transcriptional factor involving in various transcriptional regulatory networks. The results revealed that the method allowed a specific, simple, and quantitative assay of the target protein with a linear response range from 0 to 120 nM and a detection limit of 10 nM.
authors.affiliation: State Key Laboratory of Chemo/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, People's Republic of China.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Ou
authors.forename: Pei-Yan
authors.initials: PY
authors.lastname: Jin
authors.forename: Xia
authors.initials: X
authors.lastname: Chu
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Jiang
authors.forename: Ru-Qin
authors.initials: RQ
authors.lastname: Yu
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003124:Colorimetry; D004247:DNA / Q000737:chemistry; D005090:Exodeoxyribonucleases / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D035181:TATA-Box Binding Protein / Q000032:analysis*
chemical_list: D035181:TATA-Box Binding Protein; D006046:Gold; D004247:DNA; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III