Latest ArticlesThe unique structure of fluorescent proteins in which the fluorophore is encapsulated by the protein shell to restrict rotation and emit light inspired the screening of chromophores that selectively bind to biomolecules to generate fluorescence. In this paper, we report a curcuminoid-BF2-like fluorescent dye N-BF2 containing 4-dimethylaniline as an electron-donating group. When this dye is combined with HSA or BSA, the fluorescence is enhanced 90/112-fold, and the fluorescence quantum yield increases from < 0.001 to 0.16/0.19. Such a large change in fluorescence enhancement is due to the encapsulation of N-BF2 in the protein cavity by HSA/BSA, which inhibits the intramolecular rotation of the aniline moiety caused by charge transfer after the fluorophore is excited by light. N-BF2 has fast and strong binding to HSA or BSA and was found to be reversible in solution and intracellularly. Since N-BF2 also has the ability to target lipid droplets, the complex of N-BF2/HSA realizes the regulation of reversible lipid droplet staining in cells.
A novel air-stable n-type benzothiaphene endcapped azaarene (BTPQ) and its sulfonated derivative (BSPQ) were prepared via two pathways and characterized by NMR, UV–vis, fluorescence and cyclic voltammetry spectroscopy. Symmetrically introducing four nitrogen atoms into acenes, the semiconductor properties could be changed from p-type to n-type detected through the space charge limited current (SCLC) method. After sulfonation of BTPQ, BSPQ is with deeper frontier orbital energy levels and enhanced the electron mobility.
Photocatalytic recovery, a novel precious metal recycling technology, dedicates to solving the environmental and energy consumption problems caused by traditional technologies. The activation of molecular oxygen (O2) is one of the most critical steps in the whole process. Herein, we regulated the different adsorption intensity of oxygen on the surface by designing phosphate (PO43−) modified titanium oxide (TiO2). The results show that the adsorption of oxygen on the photocatalyst surface is gradually enhanced, which effectively improves the dissolution rate of precious metals. PO43− modification increased the photocatalytic dissolution rate of gold (Au) by 2.8 times. The photocatalytic activity of other precious metals dissolution (such as palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru) and iridium (Ir)) was also significantly improved. It is applied to the recovery of precious metals from spent catalysts and electronic devices to significantly promote the recovery efficiency. This indicates the direction for designing more efficient photocatalysts for precious metal recovery.
One-dimensional carbon nanofibers are widely applied as anode material in the energy storage field due to its unique structure and high conductivity. In this work, one-dimensional ZnSe@N-doped carbon nanofibers (ZnSe@NC NFs) are successfully synthesized by electrospinning and annealed without extra troublesome conditions. ZnSe nanocrystals are enfolded in the N-doped carbon nanofibers, which can act as a protective layer to avoid the volume expansion of active material and promote ion transport during the cycling process. More importantly, the as-synthesized ZnSe@NC NFs are served as the anode material and display the admirable storage properties for Na/K-ion batteries. The one-dimensional ZnSe@NC NFs material shows the high capacity of 237 mAh/g for Na-ion batteries at a current density of 1 A/g for 2000 cycles. Meanwhile, it also delivers a high discharge capacity of 337 mAh/g for K-ion batteries at 0.2 A/g for 300 cycles. Additionally, it is confirmed that the pseudocapacitive contribution of the nano-structure material is up to 54.5% at a scan rate of 0.6 mV/s through the cyclic voltammetry (CV) measurement in K-ion batteries.
Prion diseases are fatal neurodegenerative diseases that can cause severe dementia. The misfolding and accumulation of the prion peptide (PrP)106–126 is crucial, and this process is closely relevant to biological membranes. However, how PrP106–126 aggregation is affected by the molecular chirality of phospholipid membrane is unknown. Thus, in this study, a pair of L- and D-aspartic acid (Asp)-modified 1, 2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) were synthesized to construct chiral liposomes. We discover that L-Asp-DPPE liposomes strongly inhibit the oligomerization and amyloidogenesis of PrP106–126, whether acting on monomers or oligomers, which rescues cytotoxicity induced by PrP106–126. By comparison, D-Asp-DPPE liposomes inhibit peptide oligomerization only at a high concentration and cannot prevent amyloidogenesis when acting on oligomers, which lead to pronounced cytotoxicity. Apoptosis experiment, dynamic change of intracellular Ca2+ (iCa2+) and Ca2+ release from endoplasmic reticulum (ER), reactive oxygen species (ROS) production, adsorption dynamics and affinity tests, and fluorescent imaging clearly disclose that molecular chirality of the liposomes dominates conformational transition of PrP106–126 from random coil to β-sheet, binding and adsorption of the monomers and oligomers, and subsequent fibrillation process, resulting in distinct inhibition effect in Ca2+ overload and release, ROS production and cell apoptosis. This work is the first to report that interfacial molecular chirality is a potentially crucial influence on the fibrillation process of PrP106–126 and its cell responses, whereas the convergence of chiral amino acids and liposomes can be considered potential inhibitors in prion diseases.
The removal of eight typical pharmaceuticals (PhACs) (i.e., ibuprofen (IBU), ketoprofen (KET), diclofenac (DIC), sulfadiazine (SD), sulfamethoxazole (SMX), trimethoprim (TMP), ciprofloxacin (CIP) and enoxacin (ENO)) in sulfur-driven autotrophic denitrification (SdAD) process were firstly investigated via long-term operation of bioreactor coupled with batch tests. The results indicated that IBU and KET can be effectively removed (removal efficiency > 50%) compared to other six PhACs in SdAD bioreactor. Biodegradation was the primary removal route for IBU and KET with the specific biodegradation rates of 5.3±0.7~18.1±1.8 µg g−1-VSS d−1 at initial concentrations of 25-200 µg/L. The biotransformation intermediates of IBU and KET were examined, and the results indicated that IBU was biotransformed to three intermediates via hydroxylation and carboxylation. KET biotransformation could be initiated from the reduction of the keto group following with a series of oxidation/reduction reactions, and five intermediates of KET were observed in this study. The microbial community composition in the system was markedly shifted when long-term exposure to PhACs. However, the functional microbes (e.g., genus Thiobacillus) showed high tolerance to PhACs, resulting in the high efficiency for PhACs, N and S removal during long-term SdAD reactor operation. The findings provide better insight into PhACs removal in SdAD process, especially IBU and KET, and open up an innovative opportunity for the treatment of PhACs-laden wastewater using sulfur-mediated biological process.
Artificial synapses with full synapse-like functionalities are of crucial importance for the implementation of neuromorphic computing and bioinspired intelligent systems. In particular, the development of artificial synapses with the capability to emulate multiplexed neural transmission is highly desirable, but remains challenging. In this work, we proposed a hybrid ambipolar synaptic transistor that combines two-dimensional (2D) molybdenum disulfide (MoS2) sheet and crystalline one-dimensional (1D) poly(3-hexylthiophene-2, 5-diyl) polymer nanowires (P3HT NWs) as dual excitatory channels. Essential synaptic functions, including excitatory postsynaptic current, paired-pulse facilitation, synaptic potentiation and depression, and dynamic filtering were emulated using the synaptic transistor. Benefitting from the dual excitatory channels of the synaptic transistor, the device achieved a fast switch between short-term and long-term memory by altering the charge carriers in the dual channels, i.e., electrons and holes. This emulated the multiplexed neural transmission of different excitatory neurotransmitters, e.g., dopamine and noradrenaline. The plasticity-switchable artificial synapse (PSAS) simulates the task-learning process of individuals under different motivations and the impact of success or failure on task learning and memory, which promises the potential to enable complex functionalities in future neuromorphic intelligent electronics.
Polyoxometalates (POMs) are important inorganic photochromic materials to be potentially applied in photo-induced switch, energy storage, and even the detection of light. However, due to the limited sensitivity of POMs, it is difficult to realize the photochromic response to weak visible light. In this paper, by the coordination of solvated Pb(II), a new structure-defined chain-like polyoxomolybdate complex of [(Pb(DMF)4)3(P2Mo18O62)2]n (Pb3Mo18, DMF = dimethylformamide) has been demonstrated by a facile solvent-diffusion approach. By virtue of interactions between Pb(DMF)4 and polyoxoanions, Pb3Mo18 shows an ultrasensitive photochromic response to weak visible lights and forms the reduced 'heteropoly blue' species through ligand-to-metal charge transfer (LMCT) process. A new mechanism is firstly proposed here that the 6s orbital lone electron pair on Pb(II) can effectively stabilize the generated hole of oxygen atoms as a result of O→Mo charge transfer. Through the proposed mechanism, the LMCT barrier is drastically lowered and allows the coloration to be occurred even upon weak visible light. Also, because the conductivity of Pb3Mo18 enhances with the increase of reduction extent, its electrochemical impedance signals are proportionally response to irradiation intensity. Especially, for the first time, the polyoxomolybdate composite can be used to detect weak visible light, in which the optical signal can be converted into electrical signal output. Moreover, Pb3Mo18 can be drip-coated on the surface of the screen printed chip electrode, which is facile to the detection of light by portable devices compatible with computers, mobile phones and other electronic equipment. This work not only highlights a new approach to the molecular design of photochromic POMs by the coordination of metal ions with the effect of inert electron pair, but also lays a foundation to extend the application of POMs as light signal sensors.
Spiropyrans (SPs) are a well-known class of photochromic compounds and have found widespread application due to their unique properties. However, for many conventional SPs, high energy ultraviolet (UV) light is commonly essential to drive photoisomerization, leading to poor fatigue resistance. Moreover, the practical application of spiropyrans is hindered by their fast fading speed due to the instability of closed forms (SP) or open forms (MC). Herein, we disclose a novel strategy to address these challenges through introducing both electron-donating substituents to stabilize the SP and dynamic coordination bonds to stabilize the MC. The resulting new spiropyrans complexes exhibit negative photochromic properties, with fast visible light response, good stability of both SP and MC, and significantly improved fatigue resistance.
On-purpose propane dehydrogenation (PDH) has emerged as a profitable alternative to the traditional cracking of oil products for propylene production. By means of density functional theory (DFT) calculations, the present work demonstrates that Fe atoms may atomically disperse on MoS2 (Fe1/MoS2) and serve as a promising single-atom catalyst (SAC) for PDH. The catalytic activity of Fe1/MoS2 is attributed to the highly exposed d orbitals of single Fe atoms, while the propylene selectivity is originated from the kinetic inhibition of propylene dehydrogenation resulting from fast propenyl hydrogenation. The unique catalytic selectivity of Fe1/MoS2 may inspire further investigations of on-purpose dehydrogenations of propane on SACs.
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