title: QD-Biopolymer-TSPP Assembly as Efficient BiFRET Sensor for Ratiometric and Visual Detection of Zinc Ion.
abstract: In this work, we report a new type of quantum dot (QD)-based fluorescence resonance energy transfer (FRET) assembly and its utility for sensing Zn2+in different media. The assembly on the QD scaffold is via first coating of poly(dA) homopolymer/double-stranded DNA, followed by loading of meso-tetra(4-sulfonatophenyl)porphine dihydrochloride (TSPP), both of which are electrostatic, offering the advantages of cost-efficiency and simplicity. More importantly, the biopolymer coating minimizes the interfacial thickness to be ≤2 nm for QD-TSPP FRET, which results in improvements of up to 60-fold for single FRET efficiency and nearly 4-fold for total FRET efficiency of the QD-biopolymer-TSPP assemblies in comparison with silica-coating-based QD-TSPP assemblies. On the basis of Zn2+-chelation-induced spectral modulation, dual-emission QD-poly(dA)-TSPP assemblies are developed as a ratiometric Zn2+sensor with increased sensitivity and specificity. The sensor either in solution or on a paper substrate displays continuous color changes from yellow to bright green toward Zn2+, exhibiting excellent visualization capability. By utilizing the competitive displacement of Zn2+, the sensor is also demonstrated to have good reversibility. Furthermore, the sensor is successfully used to visualize exogenous Zn2+in living cells. Together the QD-biopolymer-TSPP assembly provides an inexpensive, sensitive, and reliable sensing platform not only for on-site analytical applications but also for high-resolution cellular imaging.
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, P. R. China.
authors.forename: Yuqian
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, P. R. China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Qu
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, P. R. China.
authors.forename: Qingsheng
authors.initials: Q
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, P. R. China.
authors.forename: Qingjiang
authors.identifier: http://orcid.org/0000-0001-9286-5738
authors.initials: Q
authors.lastname: Sun
authors.affiliation: School of Chemistry and Chemical Engineering, Beijing Institute of Technology , Beijing 100081, P. R. China.
authors.forename: Xuebin
authors.initials: X
authors.lastname: Huang
keywords: biopolymer; electrostatic assembly; porphyrin; quantum dot; resonance energy transfer; sensor; zinc ion