Dual-Emission Silica-Coated Quantum Dots Mixture as FRET-based
Ratiometric Fluorescence Probe for detection of Zn2+
Liang Wu, Kao Zhu, Qingsheng Guo, Yuqian Liu, Qingjiang Sun*
State Key Laboratory of Bioelectronics, School of Biological Science & Medical
Engineering, Southeast University, Nanjing 210096, China
Fax: +86-25-83792349; Email: sunqj@seu.edu.cn
Recently, quantum dots (QDs) have attracted widespread attention in diverse research
areas due to their unique spectral properties, such as high quantum yields, exceptional
resistance to photobleaching and a stable surface for further modification. Besides, their
size-dependent emission spectra with broad absorption spectra allow their simultaneous
excitation at a single wavelength. Utilizing these properties, different-colored QDs can
be combined together to develop their applications in ratiometric fluorescence detection
of protein, virus or ions.
Detection of Zn2+ is a significant issue towards human health and environment due to
its critical roles in many biological activities. Herein, we designed a new ratiometric
fluorescence probe for Zn2+ detection in aqueous phase based on two fluorescence
resonance energy transfer (FRET) processes from different-colored QDs to
meso-tetra(4-sulfonatophenyl)porphine dihydrochloride (TSPP). The probe comprises
dual-emission silica-coated QDs with TSPP assembled on the surface. By adjusting the
thickness of silica shell, TSPP quenches the photoluminescence (PL) of each QD
dominated by FRET mechanism while other interactions are shielded. The chelation of
TSPP with Zn2+ changes the absorption spectra as well as the FRET efficiency to
green-emitting QDs (gQDs) and yellow-emitting QDs (yQDs) respectively, which leads
to the PL recovery of gQDs and further PL quenching of yQDs. As a result, The color
of the probe changes from yellow to green, which can be easily observed by the naked
eye. This ratiometric probe has demonstrated to feature excellent selectivity for Zn2+
over other ions, thus potentially attractive for visual identification.
Scheme 1. Schematic diagram of the ratiometric fluorescence probe for detection of Zn2+.
Reference
1. Sun, Q. J.; Wang, Y. A. et al. Nat. Photonics 2007, 1, 717-722.
2. Sun, Q. J.; Guru, S. et al. ACS Nano 2009, 3, 737-743.
3. Xu, X. J. et al. Anal. Chem. 1991, 63, 2532-2535.
This work was funded by NSFC and SKLB (Grants: 21005017, 21375015).