Effective transfection of genetic molecules such as DNA usually relies on vectors that can reversibly uptake and release these molecules, and protect them from digestion by nuclease. Non-viral vectors meeting these requirements are rare due to the lack of specific interactions with DNA. Here, we design a series of four isoreticular metal-organic frameworks (Ni-IRMOF-74-II to -V) with progressively tuned pore size from 2.2 to 4.2 nm to precisely include single-stranded DNA (ssDNA, 11–53 nt), and to achieve reversible interaction between MOFs and ssDNA. The entire nucleic acid chain is completely confined inside the pores providing excellent protection, and the geometric distribution of the confined ssDNA is visualized by X-ray diffraction. Two MOFs in this series exhibit excellent transfection efficiency in mammalian immune cells, 92% in the primary mouse immune cells (CD4+ T cell) and 30% in human immune cells (THP-1 cell), unrivaled by the commercialized agents (Lipo and Neofect).

This review focuses on the recent progresses in epigenetic modifications in DNA and RNA, including their epigenetic roles, detection methods and applications in clinical medicine.

MicroRNA (miRNA) detection is of considerable significance in both disease diagnosis and in the study of miRNA function.

Nucleic acid circuits have shown promising potential for amplified detection of biomarkers with interest in biologically important engineering applications. In this work, by properly integrating two signal amplification approaches, catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR), a concatenated CHA–HCR system was established as an isothermal enzyme-free amplification strategy for highly sensitive and selective nucleic acid assay. The target catalyzes the self-assembly of CHA hairpin substrates into dsDNA products, where the split segments of HCR trigger are successively connected to drive the subsequent autonomous cross-opening of HCR hairpins, leading to the construction of HCR tandem copolymeric dsDNA nanowires. The resulting HCR copolymer brings a fluorophore donor/acceptor pair into close proximity that allows an efficient generation of FRET readout signal. Moreover, the optimized CHA–HCR circuit, upon the incorporation of an auxiliary sensing module, can be converted into a universal sensing platform for detecting cancerous biomarkers (e.g., a well-known oncogene miR-21) through a convenient easy-to-integrate procedure. The concatenated CHA–HCR amplifier enables accurate intracellular miRNA imaging in living cells, which is especially suitable for in situ amplified detection of lowly expressed endogenous analytes. The inherent synergistically accelerated recognition and hybridization features of CHA–HCR circuit contribute to the amplified detection of endogenous RNAs in living cells. The flexible and programmable nature of the homogeneous CHA–HCR system provides a versatile and robust toolbox for a wide range of research fields, such as in vivo bioimaging, clinical diagnosis and environmental monitoring.

After entering a cell, most small molecule fluorescent probes are dispersed in the cytoplasm before they then accumulate in a specific organelle or subcellular zone. Molecules that can enter two or more organelles with high selectivity are all but unknown. In this work, we report a naphthalimide-based fluorescent probe, NIM-7, that allows lipid droplets and lysosomes to be labelled simultaneously and with high specificity. These subcellular entities can then be visualized readily through yellow and red fluorescence, using different excitation and detection channels. NIM-7 allows 3D imaging and quantitative visualizing of lipid droplets and lysosomes. It is also able to track simultaneously the movement of lipid droplets and lysosomes in real-time. We also report here that NIM-7 can be used to image both different cell lines and zebrafish embryos.