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DNA nanotechnology plays an increasingly important role in the biomedical field; however, its application in the design of organic nanomaterials is underexplored. Herein, we report the use of DNA nanotechnology to transport a NIR-II-emitting nanofluorophore across the blood-brain barrier (BBB), facilitating non-invasive imaging of brain tumors. Specifically, the DNA block copolymer, PS-b-DNA, is synthesized through a solid-phase click reaction. We demonstrate that its self-assembled structure shows exceptional cluster effects, among which BBB-crossing is the most notable. Therefore, PS-b-DNA is utilized as an amphiphilic matrix to fabricate a NIR-II nanofluorephore, which is applied in in vivo bioimaging. Accordingly, the NIR-II fluorescence signal of the DNA-based nanofluorophore localized at a glioblastoma is 3.8-fold higher than the NIR-II fluorescence signal of the PEG-based counterpart. The notably increased imaging resolution will significantly benefit the further diagnosis and therapy of brain tumors., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new DNA-based fluorescent probe, which is a hybrid molecule of an i-motif forming sequence (IFS) and mono-functionalized tetraphenylethene (TPE), has been synthesized and investigated. A distinct pH-responsive aggregation-induced emission (AIE) effect has been observed from this hybrid molecule, i.e. the fluorescence of TPE will be turned on when the IFS part folds up under acidic conditions. According to the fact that a hybrid molecule with a relatively rigid structure shows a more obvious AIE effect, and whose nano-sized aggregates are formed at a high concentration, we assume that the solubility of the hybrid molecule in water will be reduced due to IFS folding, resulting in aggregation and the resultant AIE effect. Finally, due to its excellent pH responsiveness, this DNA-based probe employing an AIEgen has been applied in monitoring intracellular pH.

Recently, smart DNA hydrogels, which are generally formed by the self-assembly of oligonucleotides or through the cross-linking of oligonucleotide-polymer hybrids, have attracted tremendous attention. However, the difficulties of fabricating DNA hydrogels limit their practical applications. We report herein a novel method for producing pH-responsive hydrogels by rolling circle amplification (RCA). In this method, pH-sensitive cross-linking sites were introduced into the polymeric DNA chains during DNA synthesis. As the DNA sequence can be precisely defined by its template, the properties of such hydrogels can be finely tuned in a very facile way through template design. We have investigated the process of hydrogel formation and pH-responsiveness to provide rationales for functional hydrogel design based on the RCA reaction., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A rolling-circle-amplification method was developed to produce DNA hydrogels with horseradish-peroxidase-like catalytic capability. The catalytic hydrogel exhibits highly improved stability at elevated temperatures or during a long-term storage. Integrated with glucose oxidase, the complex hydrogel can be applied to the sensitive and reliable detection of glucose.

A pair of single-molecule photo-responsive DNA nanoscissors for DNA cleavage based on the regulation of substrate binding affinity was designed and fabricated. Compared with other DNA nanomachines, our DNA nanoscissors have the advantages of a clean switching mechanism, as well as robust and highly reversible operation.

A new DNA nanoprobe based on a Y-shape and pyrene-modified DNA self-assembly is developed to sensitively and specifically detect microRNA through a pyrene excimer–monomer switch. Exhibiting the capability of self-delivery and resistance to nuclease degradation, the nanoprobe has been successfully applied for microRNA imaging in live cells. [ABSTRACT FROM AUTHOR]

Based on the protective properties of polydopamine nanospheres for DNA probes against nuclease digestion, we have developed a DNase I-assisted target recycling signal amplification method for highly sensitive and selective detection of miRNA. [ABSTRACT FROM AUTHOR]

We propose the use of DNAzyme as a crosslinker of hydrogel to develop a catalytic platform for the sensing of metal ions. The DNAzyme crosslinked hydrogel can undergo gel–sol transition in response to Cu2+ions, which enables sensitive visual detection of Cu2+by observing the release of pre-trapped AuNPs. [ABSTRACT FROM AUTHOR]