Photoluminescent MOF for endogeneous sulfide sensing
Résumé
1. Introduction
According to the World health organization, the four major non-communicable diseases (NCDs, ie cardiovascular diseases, cancer, chronic respiratory diseases and diabetes) are responsible for 82% of NCDs deaths which corresponds to 31 million deaths in 2012.1 All these diseases involve a variation of H2S concentration in blood. Indeed, H2S is the 3rd endogenously generated gaseous signaling compound and it’s involved in the biological systems under physiological and pathological conditions.2 What about the development of accurate point-of-care testing3 for H2S blood concentration using fluorescent MOF as sensor? Early diagnostic will allow avoiding millions of deaths every year.
2. Results and discussion
We present a tailored MOF solid coupled for the first time with a femtosecond (fs)-pulse laser irradiation protocol to achieve the rapid in vitro detection of nanomolar sulfide in serum solutions.4
Three different MOF platforms are investigated here, namely MIL-68, MIL-101 and UiO-66. The detection is based on azido to amino turn on fluorescence upon H2S exposure (Fig. 1a).
Our azido-modified Al-MIL-101 is thus an efficient sensor for sulfide in biologically relevant media, reaching the 100 nM detection limit under laser excitation (Fig. 1b). This result is a three order of magnitude sensitivity increase with respect to previously reported fluorescent azido-MOF which detected tens to hundreds micromolar sulfide under lamp excitation.5 The limit of determination of our system (100 nM) is also lower than that reported for the Ellman reagent (600 nM), which is widely used for the detection of SH-containing compounds produced by bacteria in solution. We assign the high sensitivity of our hybrid solid sys-tem to the arrangement of organic chromophore into the rigid MOF structure which allows sensing sites isolation and has proven to reduce non-radiative emissions. The latter are moreover efficiently neutralize by the highly energetic fs-pulse laser excitation leading to heightened ligand-centered emission.
3. Conclusions
In conclusion, the Al-MIL-101-based sensor allows reaching sulfide quantification in physiological solutions after only minutes of exposure in the micro- to nanomolar range for endogenous H2S concentrations. Through the adequate tuning of irradiation protocol, the rational selection of ligand-centered emission paves the way to MOF-based device construction by design, the hybrid solid capacity being driven by an almost infinite library of organic chromophore ligands.
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 685727
References
1) Mendis, S.; Armstrong, T.; Bettcher, D.; Branca, F.; Lauer, J.; Mace, C.; Poznyak, V.; Riley, L.; Da Costa E Silva, V.; Steven, G. Global Status Report on noncommunicable diseases 2014, World Health Organization, 2015.
2) Wang, R. Physiol. Rev. 2012, 92, 791.
3) Luppa, P. B.; Müller, C.; Schlichtiger, A.; Schlebusch, H. TrAC-Trend Anal. Chem. 2011, 30, 887.
4) Legrand, A.; Pastushenko, A.; Lysenko, V.; Geloen, A.; Quadrelli, E.A.; Canivet, J.; Farrusseng, D., Submitted
5) (a) Zhang, X.; Zhang, J.; Hu, Q.; Cui, Y.; Yang, Y.; Qian, G. Appl. Surf. Sci. 2015, 355, 814. (b) Nagarkar, S. S.; Saha, T.; Desai, A. V.; Talukdar, P.; Ghosh, S. K. Sci. Rep. 2014, 4, 07053.