Peiwen Wu

An Exceptionally Simple Strategy for DNA-Functionalized Up-Conversion Nanoparticles as Biocompatible Agents for Nanoassembly, DNA Delivery, and Imaging

Lanthanide-doped up-conversion nanoparticles (UCNPs) have shown promise in biomedical applications. However, as the UCNPs are normally capped with hydrophobic ligands, it remains challenging to prepare biocompatible UCNPs with specific molecular recognition capabilities. We herein report an exceptionally simple strategy to prepare uniform DNA-modified UCNPs as versatile bioprobes. The approach can directly convert as-prepared hydrophobic UCNPs into water-soluble DNA-UCNPs without any chemical modification of UCNPs or oligonucleotides. Furthermore, DNA molecules on the DNA-UCNPs retain their biorecognition ability, allowing programmable assembly of hybrid nanostructures. More importantly, we show that these DNA-UCNPs are capable of crossing cell membranes without the need of transfection agents, and their use as agents for bioimaging and DNA delivery are also demonstrated. Finally, DNA aptamer-conjugated UCNPs can be readily used for targeted imaging of cancer cells.

One-pot extraction combined with metal-free photochemical aerobic oxidative desulfurization in deep eutectic solvent

Five low-cost deep eutectic solvents (DESs) were synthesized based on choline chloride (ChCl) and a series of straight-chain monobasic acids. Under UV light irradiation, one-pot extraction combined with the metal-free photochemical aerobic oxidative deep desulfurization of fuels in deep eutectic solvents was successfully achieved. This liquid-liquid extraction and photochemical oxidative desulfurization system (EPODS) comprised of air, isobutylaldehyde (IBA), DESs and model oil. The factors influencing sulfur removal were systematically investigated, including the amount of DES, volume ratio of model oil and IBA, different sulfur concentrations, different substrates and fuel composition. The sulfur removal of dibenzothiphene (DBT) could reach 98.6% with air as oxidizing agent under UV light irradiation. Sulfur removal by different sulfur compounds decreased as BT > DBT > 4,6-DMDBT. The possible photochemical oxidative desulfurization mechanism was researched by gas chromatograph-mass spectrometer (GC-MS), electron spin-resonance (ESR) spectroscopy and density functional theory (DFT).

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

Significance Monovalent ions, such as Na+, play important roles in biology, yet few sensors that image intracellular Na+ have been reported. Although deoxyribozymes (DNAzymes) have been shown to be a promising platform for detection of metal ions, most reported DNAzymes require multivalent metal ions for catalytic activity. Existing monovalent ion-responsive DNAzymes have poor selectivity for Na+, low catalytic rate, and require high ion concentrations for function. Here, we report in vitro selection of the first (to our knowledge) highly selective, sensitive, and efficient Na+-specific, RNA-cleaving DNAzyme and its conversion into a catalytic beacon sensor for imaging Na+ in living cells, using an efficient cationic polypeptide delivery method, together with a photocaging strategy, to allow controllable activation of the DNAzyme probe inside cells. Over the past two decades, enormous progress has been made in designing fluorescent sensors or probes for divalent metal ions. In contrast, the development of fluorescent sensors for monovalent metal ions, such as sodium (Na+), has remained underdeveloped, even though Na+ is one the most abundant metal ions in biological systems and plays a critical role in many biological processes. Here, we report the in vitro selection of the first (to our knowledge) Na+-specific, RNA-cleaving deoxyribozyme (DNAzyme) with a fast catalytic rate [observed rate constant (kobs) ∼0.1 min−1], and the transformation of this DNAzyme into a fluorescent sensor for Na+ by labeling the enzyme strand with a quencher at the 3′ end, and the DNA substrate strand with a fluorophore and a quencher at the 5′ and 3′ ends, respectively. The presence of Na+ catalyzed cleavage of the substrate strand at an internal ribonucleotide adenosine (rA) site, resulting in release of the fluorophore from its quenchers and thus a significant increase in fluorescence signal. The sensor displays a remarkable selectivity (>10,000-fold) for Na+ over competing metal ions and has a detection limit of 135 µM (3.1 ppm). Furthermore, we demonstrate that this DNAzyme-based sensor can readily enter cells with the aid of α-helical cationic polypeptides. Finally, by protecting the cleavage site of the Na+-specific DNAzyme with a photolabile o-nitrobenzyl group, we achieved controlled activation of the sensor after DNAzyme delivery into cells. Together, these results demonstrate that such a DNAzyme-based sensor provides a promising platform for detection and quantification of Na+ in living cells.

Few-layered graphene-like boron nitride induced a remarkable adsorption capacity for dibenzothiophene in fuels

Metal-free graphene-like boron nitride (BN) samples were prepared and applied as adsorbents for removing dibenzothiophene (DBT) in model oil. The results showed that the graphene-like BN exhibited a remarkable adsorption performance. The adsorption capacity could reach 28.17 mg S g−1 adsorbent. Experiments have been carried out to investigate the effects of the number of BN layers, DBT initial concentration, and temperature on DBT adsorption. Langmuir and Freundlich isotherm models were used to study the adsorption of DBT on BN. The kinetic results showed that the adsorption process was best described by the pseudo-second-order kinetic model. Density functional theory (DFT) was employed to prove that the Lewis acid–base interaction plays an important role in removing DBT over graphene-like BN.

A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization

Hexagonal boron nitride nanosheets (h-BNNs) with rather high specific surface area (SSA) are important two-dimensional layer-structured materials. Here, a solvent-mediated synthesis of h-BNNs revealed a template-free lattice plane control strategy that induced high SSA nanoporous structured h-BNNs with outstanding aerobic oxidative desulfurization performance.

Carbon-doped porous boron nitride: metal-free adsorbents for sulfur removal from fuels

Novel carbon-doped porous boron nitride (C-BN) has been successfully prepared by using 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) as a soft template and the carbon source via calcination under N2 atmosphere. Multiple techniques were applied to investigate the structure, morphology, and adsorptive desulfurization performance. The metal-free porous C-BN displayed enhanced adsorption performance for dibenzothiophene (DBT) than pure BN materials and exhibited one of the highest adsorption capacities reported up to now (49.75 mg S g−1 adsorbent according to the Langmuir isotherm model, 35.2 mg S g−1 adsorbent for 500 ppm sulfur model oil). After three times recycling, the adsorption capacity slightly decreased from 35.2 to 27.2 mg S g−1 adsorbent. The excellent adsorption performance of porous C-BN was attributed to the more exposed atoms along the edges of the pores and the stronger Lewis acid–base interactions between DBT and carbon-doped porous BN. Moreover, it is believed that this strategy to control the structure and composition of BN can be extended to incorporate other heteroatoms and control the pore size for BN materials by changing the anion or cation of the ionic liquids.

DNA sequence-dependent morphological evolution of silver nanoparticles and their optical and hybridization properties.

A systematic investigation of the effects of different DNA sequences on the morphologies of silver nanoparticles (AgNPs) grown from Ag nanocube seeds is reported. The presence of 10-mer oligo-A, -T, and -C directed AgNPs growth from cubic seeds into edge-truncated octahedra of different truncation extents and truncated tetrahedral AgNPs, while AgNPs in the presence of oligo-G remained cubic. The shape and morphological evolution of the nanoparticle growth for each system is investigated using SEM and TEM and correlated with UV-vis absorption kinetic studies. In addition, the roles of oligo-C and oligo-G secondary structures in modulating the morphologies of AgNPs are elucidated, and the morphological evolution for each condition of AgNPs growth is proposed. The shapes were found to be highly dependent on the binding affinity of each of the bases and the DNA secondary structures, favoring the stabilization of the Ag{111} facet. The AgNPs synthesized through this method have morphologies and optical properties that can be varied by using different DNA sequences, while the DNA molecules on these AgNPs are also stable against glutathione. The AgNP functionalization can be realized in a one-step synthesis while retaining the biorecognition ability of the DNA, which allows for programmable assembly.

Controllable Fabrication of Tungsten Oxide Nanoparticles Confined in Graphene-Analogous Boron Nitride as an Efficient Desulfurization Catalyst

Tungsten oxide nanoparticles (WOx NPs) are gaining increasing attention, but low stabiliity and poor dispersion of WOx NPs hinder their catalytic applications. Herein, WOx NPs were confined in graphene-analogous boron nitride (g-BN) by a one-step, in situ method at high temperature, which can enhance the interactions between WOx NPs and the support and control the sizes of WOx NPs in a range of about 4-5 nm. The as-prepared catalysts were applied in catalytic oxidation of aromatic sulfur compounds in which they showed high catalytic activity. A balance between the W loading and the size distribution of the WOx NPs could govern the catalytic activity. Furthermore, a synergistic effect between g-BN and WOx NPs also contributed to high catalytic activity. The reaction mechanism is discussed in detail and the catalytic scope was enlarged.

A large number of low coordinated atoms in boron nitride for outstanding adsorptive desulfurization performance

h-BN has been demonstrated to be able to exhibit adsorptive desulfurization from fuel. In order to further optimize the adsorption capacities to meet the potential industrial applications, tuning the nanostructure of BN was taken into account. In this work, we demonstrated that cyanamide, dicyandiamide, and melamine as different nitrogen precursors for synthesizing BN could tune the BN nanoarchitectures. The high performance BN prepared with melamine presented a ribbon-like structure which was assembled with porous nanosheets. This kind of nanoarchitecture with exposed BN sharp edges and a porous structure can be constructed on the BN surface. The large number of low coordinated atoms at the exposed sharp edges and along the edges of the pores could build powerful interaction with sulfide, which was believed to be responsible for the advanced adsorption capacity. The prepared BN with melamine as nitrogen precursors displayed remarkable adsorption performance for DBT (40.2 mg S per g adsorbent for 500 ppm sulfur model oil and 57.5 mg S per g adsorbent according to the Langmuir isotherm model). To the best of our knowledge, it is the highest adsorption capacities reported so far for the adsorptive desulfurization. It is also noteworthy to mention that even for refractory sulfur compound 4,6-DMDBT, the prepared BN still showed high adsorption performance.

Taming interfacial electronic properties of platinum nanoparticles on vacancy-abundant boron nitride nanosheets for enhanced catalysis

Taming interfacial electronic effects on Pt nanoparticles modulated by their concomitants has emerged as an intriguing approach to optimize Pt catalytic performance. Here, we report Pt nanoparticles assembled on vacancy-abundant hexagonal boron nitride nanosheets and their use as a model catalyst to embrace an interfacial electronic effect on Pt induced by the nanosheets with N-vacancies and B-vacancies for superior CO oxidation catalysis. Experimental results indicate that strong interaction exists between Pt and the vacancies. Bader charge analysis shows that with Pt on B-vacancies, the nanosheets serve as a Lewis acid to accept electrons from Pt, and on the contrary, when Pt sits on N-vacancies, the nanosheets act as a Lewis base for donating electrons to Pt. The overall-electronic effect demonstrates an electron-rich feature of Pt after assembling on hexagonal boron nitride nanosheets. Such an interfacial electronic effect makes Pt favour the adsorption of O2, alleviating CO poisoning and promoting the catalysis.