Environment‐Recognizing DNA‐Computation Circuits for the Intracellular Transport of Molecular Payloads for mRNA Imaging

Programming intelligent DNA nanocarriers for the targeted transport of molecular payloads in living cells has attracted extensive attention. In vivo activation of these nanocarriers usually relies on external light irradiation. An interest is emerging in the automatic recognition of intracellular surroundings by nanocarriers and their in situ activation under the control of programmed DNA‐computation circuits. Herein, we report the integration of DNA circuits with framework nucleic acid (FNA) nanocarriers that consist of a truncated square pyramid (TSP) cage and a built‐in duplex cargo containing an antisense strand of the target mRNA. An i‐motif and ATP aptamer embedded in the TSP are employed as logic‐controlling units to respond to H⁺ and ATP inside cellular compartments, triggering the release of the sensing element for fluorescent mRNA imaging. Logic‐controlled FNA devices could be used to target drug delivery, enabling precise disease treatment.     

Nanoparticle-Assisted Alignment of Carbon Nanotubes on DNA Origami

Aligning carbon nanotubes (CNTs) is a key challenge for fabricating CNT-based electronic devices. Herein, we report a spherical nucleic acid (SNA) mediated approach for the highly precise alignment of CNTs at prescribed sites on DNA origami. We find that the cooperative DNA hybridization occurring at the interface of SNA and DNA-coated CNTs leads to an approximately five-fold improvement of the positioning efficiency. By combining this with the intrinsic positioning addressability of DNA origami, CNTs can be aligned in parallel with an extremely small angular variation of within 10°. Moreover, we demonstrate that the parallel alignment of CNTs prevents incorrect logic functionality originating from stray conducting paths formed by misaligned CNTs. This SNA-mediated method thus holds great potential for fabricating scalable CNT arrays for nanoelectronics.     

Amidation,Esterification, and Thioesterification of a Carboxyl-Functionalized Covalent Organic Framework

Three new post-synthetic modification reactions, namely amidation, esterification, and thioesterification, were demonstrated on a novel highly crystalline two-dimensional covalent organic framework (COF), COF-616, bearing pre-installed carboxyl groups. The strategy can be used to introduce a large variety of functional groups into COFs and the modifications can be carried out under mild reaction conditions, with high yields, and an easy work-up protocol. As a proof of concept, various chelating functionalities were successfully incorporated into COF-616 to yield a family of adsorbents for efficient removal of several contaminants in the water.     

Designing Covalent Organic Frameworks with a Tailored Ionic Interface for Ion Transport across One-Dimensional Channels

A strategy based on covalent organic frameworks for ultrafast ion transport involves designing an ionic interface to mediate ion motion. Electrolyte chains were integrated onto the walls of one-dimensional channels to construct ionic frameworks via pore surface engineering, so that the ionic interface can be systematically tuned at the desired composition and density. This strategy enables a quantitative correlation between interface and ion transport and unveils a full picture of managing ionic interface to achieve high-rate ion transport. Moreover, the effect of interfaces was scaled on ion transport; ion mobility is increased in an exponential mode with the ionic interface. This strategy not only sets a benchmark system but also offers a general guidance for designing ionic interface that is key to systems for energy conversion and storage.     

A Bio-inspired Nano-pocket Spatial Structure for Targeting Uranyl Capture

Biology has evolved excellent spatial structures for high-selectivity and high-affinity capture of heavy metals. Inspired by the spatial structure of the superb-uranyl binding protein SUP, we mimic the spatial structure of SUP in metal–organic frameworks (MOFs). The MOF UiO-66-3C4N fabricated by introducing 4-aminoisophthalic acid into UiO-66 shows high uranyl adsorption capacity both in simulated seawater and in natural seawater. In natural seawater, UiO-66-3C4N exhibits 17.03 times higher uranium extraction capacity than that of vanadium, indicating the high selectivity of the adsorbent. The EXAFS analysis and DFT calculation reveal that UiO-66-3C4N forms smaller nano-pocket for uranyl capture than that of SUP protein, which can both restrict the entrance of the other interfering ions with larger size and reinforce the binding by increasing the coordination interaction, and therefore qualify the nano-pocket with high affinity and high selectivity to uranyl.     

Multivariate Modulation of the Zr MOF UiO-66 for Defect-Controlled Combination Anticancer Drug Delivery

Metal–organic frameworks (MOFs) are emerging as leading candidates for nanoscale drug delivery, as a consequence of their high drug capacities, ease of functionality, and the ability to carefully engineer key physical properties. Despite many anticancer treatment regimens consisting of a cocktail of different drugs, examples of delivery of multiple drugs from one MOF are rare, potentially hampered by difficulties in postsynthetic loading of more than one cargo molecule. Herein, we report a new strategy, multivariate modulation, which allows incorporation of up to three drugs in the Zr MOF UiO-66 by defect-loading. The drugs are added to one-pot solvothermal synthesis and are distributed throughout the MOF at defect sites by coordination to the metal clusters. This tight binding comes with retention of crystallinity and porosity, allowing a fourth drug to be postsynthetically loaded into the MOFs to yield nanoparticles loaded with cocktails of drugs that show enhancements in selective anticancer cytotoxicity against MCF-7 breast cancer cells in vitro. We believe that multivariate modulation is a significant advance in the application of MOFs in biomedicine, and anticipate the protocol will also be adopted in other areas of MOF chemistry, to easily produce defective MOFs with arrays of highly functionalised pores for potential application in gas separations and catalysis.     

High-Performance Nucleic Acid Sensors for Liquid Biopsy Applications

Circulating tumour nucleic acids (ctNAs) are released from tumours cells and can be detected in blood samples, providing a way to track tumors without requiring a tissue sample. This “liquid biopsy” approach has the potential to replace invasive, painful, and costly tissue biopsies in cancer diagnosis and management. However, a very sensitive and specific approach is required to detect relatively low amounts of mutant sequences linked to cancer because they are masked by the high levels of wild-type sequences. This review discusses high-performance nucleic acid biosensors for ctNA analysis in patient samples. We compare sequencing- and amplification-based methods to next-generation sensors for ctDNA and ctRNA (including microRNA) profiling, such as electrochemical methods, surface plasmon resonance, Raman spectroscopy, and microfluidics and dielectrophoresis-based assays. We present an overview of the analytical sensitivity and accuracy of these methods as well as the biological and technical challenges they present.     

Covalent Organic Framework for Improving Near-Infrared Light Induced Fluorescence Imaging through Two-Photon Induction

Fluorescent materials exhibiting two-photon induction (TPI) are used for nonlinear optics, bioimaging, and phototherapy. Polymerizations of molecular chromophores to form π-conjugated structures were hindered by the lack of long-range ordering in the structure and strong π–π stacking between the chromophores. Reported here is the rational design of a benzothiadiazole-based covalent organic framework (COF) for promoting TPI and obtaining efficient two-photon induced fluorescence emissions. Characterization and spectroscopic data revealed that the enhancement in TPI performance is attributed to the donor-π-acceptor-π-donor configuration and regular intervals of the chromophores, the large π-conjugation domain, and the long-range order of COF crystals. The crystalline structure of TPI-COF attenuates the π–π stacking interactions between the layers, and overcomes aggregation-caused emission quenching of the chromophores for improving near-infrared two-photon induced fluorescence imaging.     

Enantiomorphic Microvortex-Enabled Supramolecular Sensing of Racemic Amino Acids by Using Achiral Building Blocks

Chiral analysis of bioactive molecules is of increasing significance in chemical and life sciences. However, the quantitative detection of a racemic mixture of enantiomers is a challenging task, which relies on complicated and time-consuming multiple steps of chiral derivatization, chiral separation, and spectroscopic measurement. Herein, we show that, without the use of chiral molecules or pretreatment steps, the co-assembly of amino acids with achiral TPPS₄ monomers controlled by enantiomorphic microvortices allows quantitative detection of racemic or enantiomeric amino acids, through analysis of the sign and magnitude of supramolecular chirality in different outlets of a microfluidic platform. A model demonstrates that chiral microvortices can induce an initial chiral bias by bending the sheet structure, resulting in supramolecular self-assembly of TPPS₄ and amino acids of compatible chirality by the self-sorting. This sensing system may find versatile applications in chiral sensing.     

High Uptake and Fast Transportation of LiPF6 in a Porous Aromatic Framework for Solid-State Li-Ion Batteries

Solid-state Li-ion batteries (SSLIBs) have recently attracted substantial attention from scientists for the advantages of better safety performance. However, there are still several key challenges in SSLIBs that need to be addressed, such as low energy density, poor thermal stability or cycle stability, and large interface resistance. This contribution introduces a novel SSLIB with a porous aromatic framework (PAF-1) accommodating LiPF₆ that was used as the solid-state electrolyte (SSE) replacing the liquid electrolyte and diaphragm of traditional Li-ion batteries. The charge, discharge capacity, rate performance and cycle stability of the SSLIB were remarkably enhanced.     

Regulating the Coordination Environment of MOF-Templated Single-Atom Nickel Electrocatalysts for Boosting CO2 Reduction

The general synthesis and control of the coordination environment of single-atom catalysts (SACs) remains a great challenge. Herein, a general host–guest cooperative protection strategy has been developed to construct SACs by introducing polypyrrole (PPy) into a bimetallic metal–organic framework. As an example, the introduction of Mg²⁺ in MgNi-MOF-74 extends the distance between adjacent Ni atoms; the PPy guests serve as N source to stabilize the isolated Ni atoms during pyrolysis. As a result, a series of single-atom Ni catalysts (named Ni_SA-N_x-C) with different N coordination numbers have been fabricated by controlling the pyrolysis temperature. Significantly, the Ni_SA-N₂-C catalyst, with the lowest N coordination number, achieves high CO Faradaic efficiency (98 %) and turnover frequency (1622 h⁻¹), far superior to those of Ni_SA-N₃-C and Ni_SA-N₄-C, in electrocatalytic CO₂ reduction. Theoretical calculations reveal that the low N coordination number of single-atom Ni sites in Ni_SA-N₂-C is favorable to the formation of COOH* intermediate and thus accounts for its superior activity.     

Microporosity of a Guanidinium Organodisulfonate Hydrogen-Bonded Framework

Guanidinium organosulfonates (GSs) are a large and well-explored archetypal family of hydrogen-bonded organic host frameworks that have, over the past 25 years, been regarded as nonporous. Reported here is the only example to date of a conventionally microporous GS host phase, namely guanidinium 1,4-benzenedisulfonate ( p -G₂BDS ). p -G₂BDS is obtained from its acetone solvate, AcMe@ G₂BDS , by single-crystal-to-single-crystal (SC-SC) desolvation, and exhibits a Type I low-temperature/pressure N₂ sorption isotherm (SA_BET=408.7(2) m² g⁻¹, 77 K). SC-SC sorption of N₂, CO₂, Xe, and AcMe by p -G₂BDS is explored under various conditions and X-ray diffraction provides a measurement of the high-pressure, room temperature Xe and CO₂ sorption isotherms. Though p -G₂BDS is formally metastable relative to the “collapsed”, nonporous polymorph, np -G₂BDS , a sample of p -G₂BDS survived for almost two decades under ambient conditions. np -G₂BDS reverts to zCO₂@ p -G₂BDS or yXe@ p -G₂BDS (y,z=variable) when pressure of CO₂ or Xe, respectively, is applied.     

A Water-Stable Ionic MOF for the Selective Capture of Toxic Oxoanions of SeVI and AsV and Crystallographic Insight into the Ion-Exchange Mechanism

Selectively capturing toxic oxoanions of selenium and arsenic is highly desired for the remediation of hazardous waste. Ionic metal–organic frameworks (iMOFs) especially cationic MOFs (iMOF-C) as ion-exchange materials, featuring aqueous phase stability, present a robust pathway for sequestration of the oxoanions owing to their ability to prevent leaching because of their ionic nature. On account of scarcity of water-stable cationic MOFs, the capture of oxoanions of selenium and arsenic has been a major challenge and has not been investigated using iMOFs. Herein, we demonstrate large scale synthesis of cationic MOF, viz. iMOF-1C that exhibits selective capture of oxoanions of Se^VI (SeO₄²⁻) and As^V (HAsO₄²⁻) in water with a maximum sorption capacity of 100 and 85 mg g⁻¹, respectively. This represents among the highest uptake capacities observed for selenate oxoanion in MOFs. Further, the ion-exchange mechanism was directly unveiled by single crystal analysis, which revealed variable modes of host–guest binding.     

Heat-Treated Aerogel as a Catalyst for the Oxygen Reduction Reaction

Aerogels are fascinating materials that can be used for a wide range of applications, one of which is electrocatalysis of the important oxygen reduction reaction. In their inorganic form, aerogels can have ultrahigh catalytic site density, high surface area, and tunable physical properties and chemical structures—important features in heterogeneous catalysis. Herein, we report on the synthesis and electrocatalytic properties of an iron–porphyrin aerogel. 5,10,15,20-(Tetra-4-aminophenyl)porphyrin (H₂TAPP) and Fe^II were used as building blocks of the aerogel, which was later heat-treated at 600 °C to enhance electronic conductivity and catalytic activity, while preserving its macrostructure. The resulting material has a very high concentration of atomically dispersed catalytic sites (9.7×10²⁰ sites g⁻¹) capable of catalyzing the oxygen reduction reaction in alkaline solution (E_onset=0.92 V vs. RHE, TOF=0.25 e⁻ site⁻¹ s⁻¹ at 0.80 V vs. RHE).     

Redox-Active Two-Dimensional Covalent Organic Frameworks (COFs) for Selective Reductive Separation of Valence-Variable,Redox-Sensitive and Long-Lived Radionuclides

We report the first example of 2D covalent organic framework nanosheets (Redox-COF1) for the selective reduction and in situ loading of valence-variable, redox-sensitive and long-lived radionuclides (abbreviated as VRL nuclides). Compared with sorbents based on chemical adsorption and physical adsorption, the redox adsorption mechanism of Redox-COF1 can effectively reduce the impact of functional group protonation under the usual high-acidity conditions in chemisorption, and raise the adsorption efficiency from the monotonous capture by pores in physisorption. The adsorption selectivity for UO₂²⁺ reaches up to unprecedented ca. 97 % at pH 3, more than for any analogous adsorbing material.     

Facile and Versatile Synthesis of End-Functionalized Poly(phenylacetylene)s: A Multicomponent Catalytic System for Well-Controlled Living Polymerization of Phenylacetylenes

A rhodium-based multicomponent catalytic system for well-controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench-stable [Rh(nbd)Cl]₂, aryl boronic acid derivatives, diphenylacetylene, 50 % aqueous KOH, and PPh₃. This system offers a method for the facile and versatile synthesis of various end-functionalized cis-stereoregular poly(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers. The polymerization reaction shows a typical living nature with a high initiation efficiency, and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrow molecular-weight distributions (M_w/M_n=1.02–1.09). The experimental results suggest that the present catalytic system has a higher polymerization activity than the polymerization activities of other rhodium-based catalytic systems previously reported.     

Self-Assembly of Highly Stable Zirconium(IV) Coordination Cages with Aggregation Induced Emission Molecular Rotors for Live-Cell Imaging

The self-assembly of highly stable zirconium(IV)-based coordination cages with aggregation induced emission (AIE) molecular rotors for in vitro bio-imaging is reported. The two coordination cages, NUS-100 and NUS-101, are assembled from the highly stable trinuclear zirconium vertices and two flexible carboxyl-decorated tetraphenylethylene (TPE) spacers. Extensive experimental and theoretical results show that the emissive intensity of the coordination cages can be controlled by restricting the dynamics of AIE-active molecular rotors though multiple external stimuli. Because the two coordination cages have excellent chemical stability in aqueous solutions (pH stability: 2–10) and impressive AIE characteristics contributed by the molecular rotors, they can be employed as novel biological fluorescent probes for in vitro live-cell imaging.     

Single-Sided Competitive Axial Coordination of G-Quadruplex/Hemin as Molecular Switch for Imaging Intracellular Nitric Oxide

Axial coordination is a crucial biological process to regulate biomolecules’ functions in natural enzymes. However, it is a great challenge to determine the single or dual axial interaction between the metal center of enzymes and the ligand. In this work, a controllable axial coordination system was developed based on G-quadruplex/hemin complex by designing a series of fluorescent derivatives. The mechanism on axial coordination of G-quadruplex/hemin with coumarin-imidazole ligands was proposed to be single-sided, and led to fluorescence quenching of ligands. Upon addition of nitric oxide, the fluorescence of ligands was recovered through competitive axial coordination, providing a “signal on” strategy for signal transduction. More significantly, the fluorescent imaging of intracellular nitric oxide was achieved after conjugating with gold nanoparticles. Also, the proposed protocol provided a smart strategy to monitor the relationship between nitric oxide and p53 protein activity in living cells.