The detection of target DNA based on a quenching mechanism with fluorescently-labeled probe single-stranded (ss)-DNA has recently emerged as a powerful and extensively applied strategy due to its enormous applications in clinical diagnosis and the therapeutic field (Sassolas, A. et al., DNA biosensors and microarrays. Chem Rev. 2008; 108(1): 109-39, Kannan, B. et al., High-sensitivity, label-free DNA sensors using electrochemically active conducting polymers. Anal Chem. 2011; 83(9): 3415-21). Numerous materials have been employed as quenching platforms for labeled probe DNA for the determination of target DNA or RNA, including graphene oxide, macro-porous silicon and carbon nanomaterials. Although these materials function well to assay target DNA or RNA, their preparation is often complicated, time-consuming and expensive. As a consequence, further sensing platforms made from easily accessible materials are urgently required.
Owing to the advantage of easily obtained raw materials, mild reaction conditions and convenient preparation procedures, as well as their variety of configurations, metal-organic frameworks (MOFs) have increasingly attracted the interest of chemists and biologists and have been successfully applied in many fields of biomedicines, such as drug delivery, magnetic resonance imaging and others. In addition, MOFs have also been used in the detection of various cations, anions, vapors and other small molecules.
Recently, MOFs have been reported as sensing platforms for biomolecules, such as proteins, nucleic acids, antibodies and G quadruplexes (e.g. Zhu, X. et al., Metal-organic framework (MOF): a novel sensing platform for biomolecules. Chem Commun (Camb). 2013; 49(13): 1276-8, Chen, L. et al., Metal-organic frameworks-based biosensor for sequence-specific recognition of double-stranded DNA. Analyst. 2013; 138(12): 3490-3, Fang, J. M. et al, Metal-organic framework MIL-101 as a low background signal platform for label-free DNA detection. Analyst. 2014; 139(4): 801-6, Zhang, H.T. et al., An amine-functionalized metal-organic framework as a sensing platform for DNA detection. Chem Commun (Camb). 2014; 50(81): 12069-72). This may rely on the fact that the organic linkers in MOFs usually have conjugated π-electron systems, which makes it possible to form π-π stacking with nucleic acid sequences. However, such development is still at its infant stage because of the poor water stability of most reported MOFs (Greathouse, J. A. and Allendorf, M. D., The interaction of water with MOF-5 simulated by molecular dynamics. J Am Chem Soc. 2006; 128(33): 10678-9, Zhang, J. W. et al., Water-stable metal-organic frameworks with intrinsic peroxidase-like catalytic activity as a colorimetric biosensing platform. Chem Commun (Camb). 2014; 50(9): 1092-4, Zheng, J. et al., Stable porphyrin Zr and Hf metal-organic frameworks featuring 2.5 nm cages: high surface areas, SCSC transformations and catalyses. Chem Sci. 2015; 6: 3466-70).
Accordingly, there remains a strong need for improved compounds which are easily obtainable in an economic way with sufficient water stability and sufficient DNA or RNA binding ability which are suitable to form sensing platforms for target DNA or RNA such as in the diagnosis of viral infectious diseases and in particular HIV infections.