Upconversion Luminescence-Controlled DNA Computation for Spatiotemporally Resolved, Multiplexed Molecular Imaging.

DNA-based molecular circuits able to perform complex information processing in biological systems are highly desirable. However, conventional DNA circuits are constitutively always in an ON state and immediately operate when they meet the biomolecular inputs, precluding precise molecular computation at a desired time and in a desired site. In this work, we report a conceptual methodology for the construction of photonic nanocircuits that enable DNA molecular computation in vitro and in vivo with high spatial precision. Upon remote activation by spatially restricted NIR-light input, two types of cancer biomarker inputs can sequentially trigger conformational changes of the DNA circuit through a structure-switching aptamer and toehold-mediated strand exchange, leading to release of a signaling output. Of note, the NIR-light-gated nanocircuit allows for intended control over the specific timing and location of DNA computation, providing spatial and temporal capabilities for multiplexed imaging. Furthermore, an OR-AND-gated nanocircuit of higher complexity was designed to illustrate the versatility of our approach. The present work illustrates the potential of the use of upconversion nanotechnology as a regulatory tool for spatial and temporal control of DNA computation in cells and animals.

Near-Infrared Light-Initiated Hybridization Chain Reaction for Spatially and Temporally Resolved Signal Amplification.

Precise control over signal amplification provides unparalleled opportunities for diverse applications. However, spatiotemporally controlled amplification has not been realized because of the lack of a design methodology. The aim of this study was thus to develop a conceptual approach for remote control over signal amplification at a chosen time and site in living cells. This system was constructed by re-engineering the functional units of the hybridization chain reaction (HCR) and combination with upconversion photochemistry, thus resulting in an activatable HCR with the high spatial and temporal precision of near-infrared (NIR) light. As a proof of concept, we demonstrate the spatially and temporally resolved amplified imaging of messenger RNA (mRNA) with ultrahigh sensitivity in vitro and in vivo. Furthermore, by using a system targeting subcellular sites we have developed a new technique for NIR-initiated amplified imaging of mRNA exclusively within a specific organelle.

Synthesis and third-order nonlinear optical properties of triphenylene derivatives modified by click chemistry.

A series of asymmetric triphenylene derivatives containing typical D-π-A structures is successfully synthesized by means of [2+2] cycloaddition-cycloreversion click reactions. The photophysical and electrochemical properties, as well as the click reactions, are characterized by means of UV/Vis absorption spectroscopy, cyclic voltammetry, and DFT modulations. In addition, the third-order nonlinear properties, including the nonlinear absorption and the nonlinear susceptibilities, are investigated by using Z-scan techniques. A typical reverse saturable absorption-saturable absorption behavior is observed for the third-order nonlinear absorption, with the third-order nonlinear susceptibilities of the compounds being 1.05×10(-12) , -1.50×10(-12) , and -0.52×10(-12) esu, respectively.

Determination of trace amount of Cu2+ with a multi-responsive colorimetric and reversible chemosensor.

A multi-responsive sensor 1 was constructed by combining a ferrocene unit and a rhodamine block via a carbohydrazone bond. The sensor showed high selectivity toward Cu(2+) over other common metal ions in a wide pH range with excellent reversibility and rapid response. The obvious color change from colorless to pink upon the addition of Cu(2+) could make it a suitable 'naked-eye' indicator for Cu(2+). The detection limit (LOD) obtained was down to 2.0 nM and the association constant (Ka) was evaluated as 4.65 × 10(7) M(-1). The accuracy for detecting Cu(2+) in environmental river water was compared favorably with the traditional atomic absorption spectroscopy method (AAS). Finally, we proposed a reversible ring-opening mechanism (Off-On) of the rhodamine spirolactam induced by Cu(2+) binding and a 2 : 1 stoichiometric structure between 1 and Cu(2+).

Application of fully conjugated covalent organic frameworks in photocatalytic carbon dioxide reduction performance.

Photocatalytic reduction of carbon dioxide into useful feedstocks has attracted increasing attention. In this study, a fully conjugated COF material COF-TMT-A with the main structure containing an alkyne group and triazine part was synthesized using sp2-carbon-carbon double bond (CC) linked COF as a research target. The prepared COF materials were characterized in detail by FT-IR, PXRD, and 13C solid-state NMR. The introduction of an alkyne group not only enhanced the conjugated π-electron leaving domain but also optimized the electronic band structure and significantly improved the photocatalytic activity. The selectivity for the product HCOO was as high as 99%. A 10 h photocatalytic CO2 reduction experiment was carried out, and COF-TMT-A showed a significantly higher HCOO- yield of about 43 µmol compared with COF-701 and the ligand.

Highly Selective Separation Intermediate-Size Anionic Pollutants from Smaller and Larger Analogs via Thermodynamically and Kinetically Cooperative-Controlled Crystallization.

Selective separation of organic species, particularly that of intermediate-size ones from their analogs, remains challenging because of their similar structures and properties. Here, a novel strategy is presented, cooperatively (thermodynamically and kinetically) controlled crystallization for the highly selective separation of intermediate-size anionic pollutants from their analogs in water through one-pot construction of cationic metal-organic frameworks (CMOFs) with higher stabilities and faster crystallization, which are based on the target anions as charge-balancing anions. 4,4'-azo-triazole and Cu2+ are chosen as suitable ligand and metal ion for CMOF construction because they can form stronger intermolecular interaction with p-toluenesulfonate anion (Ts-) compared to its analogs. For this combination, a condition is established, under which the crystallization rate of a Ts--based CMOF is remarkably high while those of analog-based CMOFs are almost zero. As a result, the faster crystallization and higher stability cooperatively endow the cationic framework with a close-to-100% selectivity for Ts- over its analogs in two-component mixtures, and this preference is retained in a practical mixture containing more than seven competing (analogs and inorganic) anions. The nature of the free Ts- anion in the cationic framework also allows the resultant CMOF to be recyclable via anion exchange.

Highly Efficient Separation of Anionic Organic Pollutants from Water via Construction of Functional Cationic Metal-Organic Frameworks and Mechanistic Study.

Organic anions possess various functional properties; however, their presence in wastewater causes environmental pollution. Thus, coupling the separation of such species with the resultant function could be highly desirable. Herein, we propose a "killing two birds with one stone" strategy for highly efficient separation of organic pollutant anions from water at room temperature through direct construction of functional cationic metal-organic frameworks (CMOFs) based on the organic anions as charge-balancing anions. To illustrate this strategy, 2,4,6-trinitrophenolate anion (PA-) is chosen as a typical anion, while 4,4'-azo-triazole (atrz) is strategically chosen as a suitable neutral ligand. The resultant positive framework exhibits a high adsorption capacity and selectivity for PA-. Remarkably, its adsorption capacity is 869.6 mg g-1, which is more than 30 times that of multiwalled carbon nanotubes and 15 times that of activated carbon. Its capacity is even higher than that of BUT-13 (865 mg g-1), the highest adsorbent ever known. 1H NMR and single-crystal X-ray diffraction show that the high capacity is attributed to strong electrostatic interaction between the positive framework and PA-, which leads to all the pores being completely occupied by PA- anions. 1H NMR titration reveals that the selectivity comes from stronger hydrogen-bonding interaction between the ligand of the positive framework and PA-, which is confirmed from the eight times length of the shifted signal of atrz due to the addition of PA- compared with the competing anions. The stronger interaction is further confirmed from the high stability of the resultant CMOF in high-concentration salt solutions containing the competing anions, particularly in 100-fold molar NaNO3 and Na2SO4 solutions. Meanwhile, first-principles simulation shows that the high binding energy between the positive framework and PA- contributes to enhancing the selectivity. Moreover, the resultant CMOF is a potential energetic material with an improved oxygen balance, high heat of formation, and heat of detonation.

NIR-light-mediated spatially selective triggering of anti-tumor immunity via upconversion nanoparticle-based immunodevices.

Immunomodulatory therapies are becoming a paradigm-shifting treatment modality for cancer. Despite promising clinical results, cancer immunotherapy is accompanied with off-tumor toxicity and autoimmune adverse effects. Thus, the development of smarter systems to regulate immune responses with superior spatiotemporal precision and enhanced safety is urgently needed. Here we report an activatable engineered immunodevice that enables remote control over the antitumor immunity in vitro and in vivo with near-infrared (NIR) light. The immunodevice is composed of a rationally designed UV light-activatable immunostimulatory agent and upconversion nanoparticle, which acts as a transducer to shift the light sensitivity of the device to the NIR window. The controlled immune regulation allows the generation of effective immune response within tumor without disturbing immunity elsewhere in the body, thereby maintaining the antitumor efficacy while mitigating systemic toxicity. The present work illustrates the potential of the remote-controlled immunodevice for triggering of immunoactivity at the right time and site.

Light-Activated Nanoprobes for Biosensing and Imaging.

Fluorescent nanoprobes are indispensable tools to monitor and analyze biological species and dynamic biochemical processes in cells and living bodies. Conventional nanoprobes have limitations in obtaining imaging signals with high precision and resolution because of the interference with biological autofluorescence, off-target effects, and lack of spatiotemporal control. As a newly developed paradigm, light-activated nanoprobes, whose imaging and sensing activity can be remotely regulated with light irradiation, show good potential to overcome these limitations. Herein, recent research progress on the design and construction of light-activated nanoprobes to improve bioimaging and sensing performance in complex biological systems is introduced. First, recent innovative strategies and their underlying mechanisms for light-controlled imaging are reviewed, including photoswitchable nanoprobes and phototargeted nanosystems. Subsequently, a short highlight is provided on the development of light-activatable nanoprobes for biosensing, which offer possibilities for the remote control of biorecognition and sensing activity in a precise manner both temporally and spatially. Finally, perspectives and challenges in light-activated nanoprobes are commented.

A photochromic upconversion nanoarchitecture: towards activatable bioimaging and dual NIR light-programmed singlet oxygen generation.

The precise control of singlet oxygen (1O2) generation is in great demand for biological studies and precision medicine. Here, a nanoarchitecture is designed and synthesized for generating 1O2 in a dual NIR light-programmable manner, while shifting to the therapeutic window. The nanoarchitecture is constructed by controlled synthesis of mesoporous silica-coated upconversion nanoparticles (UCNPs), wherein the porphyrin photosensitizers (PSs) are covalently embedded inside the silica walls while NIR (808 nm)-responsive diarylethene (DAE) photochromic switches are loaded in the nanopores. Upon irradiation with 980 nm NIR light, the UCNP core absorbs low energy photons and transfers energy to the PSs in the silica wall, leading to efficient 1O2 generation. Furthermore, this 980 nm NIR light photosensitized activity can be remotely controlled by irradiation with a distinct NIR wavelength (808 nm). The 1O2 generation is inhibited when the DAE installed in the nanopores is in the closed form, whereas irradiation of the nanoconstruct with 808 NIR light leads to the transformation of DAE to the open form, and thus enabling full recovery of the 980 nm NIR light excited 1O2 generation capability. The NIR light-mediated on-demand "activation" of the nanoarchitecture for bioimaging and controllable photodynamic therapy is further demonstrated in vitro and in vivo.

Application of Near-IR Absorption Porphyrin Dyes Derived from Click Chemistry as Third-Order Nonlinear Optical Materials.

Recently, third-order nonlinear properties of porphyrins and porphyrin polymers and coordination compounds have been extensively studied in relation to their use in photomedicine and molecular photonics. A new functionalized porphyrin dye containing electron-rich alkynes was synthesized and further modified by formal [2+2] click reactions with click reagents tetracyanoethylene (TCNE) and 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ). The photophysical properties of these porphyrin dyes, as well as the click reaction, were studied by UV/Vis spectroscopy. In particular, third-order nonlinear optical properties of the dyes, which showed typical d-π-A structures, were characterized by Z-scan techniques. In addition, the self-assembly properties were investigated through the phase-exchange method, and highly organized morphologies were observed by scanning electron microscopy (SEM). The effects of the click post-functionalization on the properties of the porphyrins were studied, and these functionalized porphyrin dyes represent an interesting set of candidates for optoelectronic device components.