Yunxi Cui

Photodynamic therapy (PDT) is a newly emerged strategy for disease treatment. One challenge of the application of PDT drugs is the side‐effect caused by the non‐specificity of the photosensitive molecules. Most of the photosensitizers may invade not only the pathogenic cells but also the normal cells. In recent, people tried to use special cargoes to deliver the drugs into target cells. DNA nanoflowers (NFs) are a kind of newly‐emerged nanomaterial which constructed through DNA rolling cycle amplification (RCA) reaction. It is reported that the DNA NFs were suitable materials which have been widely applied as nanocargos for drug delivery in cancer chemotherapeutic treatment. In this paper, we have introduced a new multifunctional DNA NF which could be prepared through an one‐pot RCA reaction. This proposed DNA NF contained a versatile AS1411 G‐quadruplex moiety, which plays key roles not only for specific recognition of cancer cells but also for near‐infrared ray based photodynamic therapy when conjugating with a special porphyrin molecule. We demonstrated that the DNA NF showed good selectivity toward cancer cells, leading to highly efficient photo‐induced cytotoxicity. Moreover, the in vivo experiment results suggested this DNA NF is a promising nanomaterial for clinical PDT.

Fluorescent molecular probes are very powerful tools that have been generally applied in cell imaging in the research fields of biology, pathology, pharmacology, biochemistry, and medical science. In the last couple of decades, numerous molecular probes endowed with high specificity to particular organelles have been designed to illustrate intracellular images in more detail at the subcellular level. Nowadays, the development of cell biology has enabled the investigation process to go deeply into cells, even at the molecular level. Therefore, probes that can sketch a particular organelle’s location while responding to certain parameters to evaluate intracellular bioprocesses are under urgent demand. It is significant to understand the basic ideas of organelle properties, as well as the vital substances related to each unique organelle, for the design of probes with high specificity and efficiency. In this review, we summarize representative multifunctional fluorescent molecular probes developed in the last decade. We focus on probes that can specially target nuclei, mitochondria, endoplasmic reticulums, and lysosomes. In each section, we first briefly introduce the significance and properties of different organelles. We then discuss how probes are designed to make them highly organelle-specific. Finally, we also consider how probes are constructed to endow them with additional functions to recognize particular physical/chemical signals of targeted organelles. Moreover, a perspective on the challenges in future applications of highly specific molecular probes in cell imaging is also proposed. We hope that this review can provide researchers with additional conceptual information about developing probes for cell imaging, assisting scientists interested in molecular biology, cell biology, and biochemistry to accelerate their scientific studies.

Cell–cell aggregation is one of the most well‐known modes of intercellular communication. The aggregation also plays a vital role in the formation of multicellularity, thus manipulating the growth and development of organisms. In the past decades, cell–cell aggregation‐related bioprocesses and molecular mechanisms have attracted enormous interest from scientists in biology, and bioengineering. People have developed a series of strategies to artificially regulate cell–cell aggregation through chemical–biological approaches. To date, not only the chemical reagents such as coordination compounds and polymers but also the biomacromolecules such as proteins and nucleic acids, are employed as the “cell glue” to achieve the control of the cell aggregation. So it is meaningful to review the recent advances of the chemical–biological approaches in cell–cell aggregation manipulation. In this review, we discuss the mechanisms and features of recently developed strategies to control cell–cell aggregation. We introduce molecules and designs relying on chemical reactions and biological conjugations respectively, and talk about their advantages and suitable applications. A perspective on the challenges in future applications in cell manipulation and cell‐based therapy is also proposed. We expect this review could inspire innovative work on manipulating cell–cell aggregation and further modulate cell–cell interactions in the research of bio/chemical fields.

In recent years, DNA has been widely noted as a kind of material that can be used to construct building blocks for biosensing, in vivo imaging, drug development, and disease therapy because of its advantages of good biocompatibility and programmable properties. However, traditional DNA-based sensing processes are mostly achieved by random diffusion of free DNA probes, which were restricted by limited dynamics and relatively low efficiency. Moreover, in the application of biosystems, single-stranded DNA probes face challenges such as being difficult to internalize into cells and being easily decomposed in the cellular microenvironment. To overcome the above limitations, DNA nanostructure-based probes have attracted intense attention. This kind of probe showed a series of advantages compared to the conventional ones, including increased biostability, enhanced cell internalization efficiency, accelerated reaction rate, and amplified signal output, and thus improved in vitro and in vivo applications. Therefore, reviewing and summarizing the important roles of DNA nanostructures in improving biosensor design is very necessary for the development of DNA nanotechnology and its applications in biology and pharmacology. In this perspective, DNA nanostructure-based probes are reviewed and summarized from several aspects: probe classification according to the dimensions of DNA nanostructures (one, two, and three-dimensional nanostructures), the common connection modes between nucleic acid probes and DNA nanostructures, and the most important advantages of DNA self-assembled nanostructures in the applications of biosensing, imaging analysis, cell assembly, cell capture, and theranostics. Finally, the challenges and prospects for the future development of DNA nanostructure-based nucleic acid probes are also discussed.

Cell motions such as migration and change in cellular morphology are essential activities for multicellular organism in response to environmental stimuli. These activities are a result of coordinated clustering/declustering of integrin molecules at the cell membrane. Here, we prepared DNA origami nanosprings to modulate cell motions by targeting the clustering of integrin molecules. Each nanospring was modified with arginyl-glycyl-aspartic acid (RGD) domains with a spacing such that when the nanospring is coiled, the RGD ligands trigger the clustering of integrin molecules, which changes cell motions. The coiling or uncoiling of the nanospring is controlled, respectively, by the formation or dissolution of an i-motif structure between neighboring piers in the DNA origami nanodevice. At slightly acidic pH (<6.5), the folding of the i-motif leads to the coiling of the nanospring, which inhibits the motion of HeLa cells. At neutrality (pH 7.4), the unfolding of the i-motif allows cells to resume mechanical movement as the nanospring becomes uncoiled. We anticipate that this pH-responsive DNA nanoassembly is valuable to inhibit the migration of metastatic cancer cells in acidic extracellular environment. Such a chemo-mechanical modulation provides a new mechanism for cells to mechanically respond to endogenous chemical cues.

In this paper, a capillary-based microfluidic whispering gallery mode (WGM) microresonator is proposed to dynamically monitor the conformation change of G-quadruplex driven by K+ ion. We have theoretically analyzed the resonance wavelength shift mechanism for the DNA folding process, and the resonance mode with the largest wavelength sensitivity of 995.63 nm/RIU according to our simulation result is selected for monitoring of the DNA folding as well as the PGQS immobilization processes. The experimentally observed resonance wavelength shift caused by the immobilization of streptavidin is in accordance with our theoretical analysis on the WGM properties of the proposed microresonator. Moreover, experimental results indicate that PGQS could be folded with a KCl concentration down to 1 μM and a resonance wavelength shift rate of 18.85°10-5 nm/s, which decreases to 2.03°10-5 nm/s when the KCl concentration increases to 10 mM due to the reduction of available PGQS folding sites. Our proposed WGM-microresonator-based measurement platform possesses many desirable merits such as high sensitivity, high integration, microfluidic, label-free and realtime monitoring operation, which make it a promising candidate for DNA sensing, measurement of trivial amount biochemical analyte and related applications.

Developing highly efficient and nontoxic drug carriers, which can work well for both chemotherapy drugs and photosensitizers, is an urgent demand to improve the efficacy of chemo‐photodynamic therapy and to promote its clinical applications. In this paper, a facile way is proposed to construct a DNA‐based nanocarrier, to achieve the synergetic loading and delivery of doxorubicine (Dox) and porphyrin/G‐quadruplex composited photosensitizer. The nanocarrier contains a gold nanoparticle (AuNP) core and a DNA layer. It is prepared via a nontemplated extension of short DNA primers on AuNP core through terminal deoxynucleotidyl transferase catalysis and subsequent DNA hybridization. Through the intercalation of Dox in duplex DNA and the forming of porphyrin/G‐quadruplex complex, the drugs responsible for chemotherapy and photodynamic therapy are efficiently loaded in the nanocarrier, and then delivered to and accumulated at tumor sites. Inside tumor cells, i‐motif may form under acidic conditions, thus triggering pH‐responsive payload release, and making the drug concentration achieving the therapeutic limitation in a short time. Highly efficient drug delivery and antitumor performance of the nanocarrier system are well demonstrated by both in vitro and in vivo experiments. The proposed nanocarrier may be developed as a promising tool for clinical drug delivery and disease therapy.

For proteins and DNA secondary structures such as G-quadruplexes and i-motifs, nanoconfinement can facilitate their folding and increase structural stabilities. However, properties of physiologically prevalent B-DNA duplex have not been elucidated inside nanocavity. By using a 17-bp DNA duplex in the form of a hairpin stem, here, we probed folding and unfolding transitions of the hairpin DNA duplex inside a DNA origami nanocavity. Compared to the free solution, the DNA hairpin inside the nanocage with a 15×15 nm cross section showed a drastic decrease in mechanical (20→9 pN) and thermodynamic (25→6 kcal/mol) stabilities. Free energy profiles revealed that activation energy of unzipping the hairpin DNA duplex decreased dramatically (28→8 kcal/mol) whereas the transition state moved closer to the unfolded state inside nanocage. All these indicate that nanoconfinement weakens the stability of hairpin DNA duplex to an unexpected extent. In a DNA hairpin made of a stem that contains complementary telomeric G-quadruplex (GQ) and i-motif (iM) forming sequences, the formation of the Hoogsteen base pairs underlining the GQ or iM is preferred over the Watson-Crick base pairs in the DNA hairpin. These results shed light on the behavior of DNA in nanochannels, nanopores, or nanopockets of various natural or synthetic machineries. It also elucidates an alternative pathway to populate non-canonical DNA over B-DNA in cellular environment where nanocavity is abundant.