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 Zn 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 Zn-chelation-induced spectral modulation, dual-emission QD-poly(dA)-TSPP assemblies are developed as a ratiometric Zn 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 Zn, exhibiting excellent visualization capability. By utilizing the competitive displacement of Zn, the sensor is also demonstrated to have good reversibility. Furthermore, the sensor is successfully used to visualize exogenous Zn 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.

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Rational Design of Polymeric Nanoparticles with Tailorable Biomedical Functions for Cancer Therapy

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Ratiometric optical nanoprobes enable accurate molecular detection and imaging

“…170 Motivated by this seminal work, more FRET-based nanostructures based on nanoparticle-dye complexes have been developed for ratiometric sensing and imaging both in vitro and in vivo . Among reported dual-emitting nanoparticle-dye nanoconjugates, core nanomaterials include FRET donors such as QDs, 171–176 GQDs, 177 Cdots, 178–183 Pdots, 184–186 fluorescence MOF, 187 and persistent luminescence nanoparticles (PLNPs), 188 whereas the dyes for FRET acceptors have been traditional organic dyes or fluorescent proteins. 189 Recently, Wu et al reported Cdot-based fluorescent nanoprobes for ratiometric sensing and imaging of intracellular hydrogen peroxide (H 2 O 2 ) based on FRET, where Cdots were used as the FRET donor and the nanocarrier for covalent attachment of a triphenylphosphonium (TPP) ligand for mitochondria targeting and a boronate-protected fluorescein (PFl) for H 2 O 2 recognition (Fig.…”