Latest ArticlesIn recent years, multicolor cascade supramolecular assemblies with controllable topological morphology have become a research hotspot due to their wide application in light-emitting materials, cell imaging and other fields. Herein, several kinds of macrocycles including cucurbiturils, calixarene and cyclodextrins are used as building blocks to construct fluorescent assemblies with anthryl-conjugated phenylpyridine (G), wherein cucurbit[8]uril (CB[8]) and G can form nanowires at a stoichiometric ratio of n: n through host-guest encapsulation to form a non-covalent heterodimer. Significantly, the macrocycle confinement effect drastically enhances the fluorescence emission of G and emission peak generated bathochromic shift from 500 nm to 600 nm. When the supramolecular polymer is further assembled with amphiphilic calix[4]arene (SC4A8), the fluorescence emission of G⊂CB[8] further increases to 1.4 times, accompanied by the morphological transformation from linear structure to nanorod structure. Subsequently, a very small amount of dye Cy5 is added to the assembly solution as an energy receptor, and the negatively charged G⊂CB[8]@SC4A8 system is regarded as an energy donor. The efficient energy transfer process enables near-infrared (NIR) emission at 675 nm with 71% energy transfer efficiency (ΦET) at a donor/receptor ratio of 100:1. Finally, the cascade supramolecular assembly has been successfully applied to targeted imaging in the nucleus of HeLa and A549 cancer cells.
Reliable and selective sensing of dopamine (DA) is essential for early diagnosis of mental diseases. Among the various potential methods, nanozyme-based sensing systems have demonstrated promising sensitivity and reliability. However, owing to the lack of substrate specificity, it is challenging to selectively detect DA using nanozymes. Herein, based on the reactivity of the DA oxidation intermediates, we report a cascade colorimetric sensing system for the selective detection of DA using only a single nanozyme. It was disclosed that the oxidation product of DA catalyzed by Co-N-doped carbon sheets (Co-N-C, a common oxidase-like nanozyme), dopamine quinone (DAQ), showed significant biocatalytic electron-donating activity in the reduction of O2 to generate O2•−. Further using O2•− to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB), a colorimetric sensing platform for DA was constructed with a linear detection range of 50 nmol/L to 50 µmol/L and a low limit of detection of 4 nmol/L. Thanks to the reactivity of the oxidation product, without any biometric units (such as nucleic acids, enzymes, and antibodies/antigens), the reaction selectivity of DA against other interferences (e.g., ascorbic acid, adrenaline, 5-hydroxytryptamine, and glutathione) was enhanced up to 71-fold. Beyond complicated cascade systems requiring at least two nanozymes, sophisticated artificial recognition via multiple interactions was simplified by exploiting the oxidative properties of product intermediates; thus, only a single common oxidase-like nanozyme was needed. This work offers a new strategy to enhance the selectivity of nanozymes for bioanalytical applications.
Directed self-assembly has been used to create micro-nano scale patterns, including chiral periodic structures of organic molecules, for potential applications in optics, photonics, metamaterials, and medical and sensing technologies. This study presents a straightforward approach for fabricating large-scale chiral grating porphyrin assemblies through template-assisted techniques. The solution of tetrakis(4-sulfonatophenyl)porphyrin (TPPS) was induced by chiral amino acids (L/D-arginine and L/D-serine) to self-assemble into highly ordered chiral grating structures with the assistance of sodium dodecyl sulfate (SDS). The structures show precise line widths (5.5 µm) and gaps (18 µm). Using in situ optical microscopy and second harmonic generation (SHG) microscopy, the chiral characteristics and dynamic evolution of the template-assisted self-assembly are investigated. It is found that the chirality of amino acids induced TPPS self-assembled into chiral structures and the liquid contraction interface significantly enhanced the chirality of the assemblies. This study is significant for understanding the mechanism of chiral evolution and designing novel micro-nano materials with predetermined chiral properties.
GPCRs are dominant targets for approved drugs and the discovery of lead compound targeting them is still challengeable. Affinity-based screening technique is a promising platform to uncover GPCR ligands. However, the intrinsic activities of them are seldom simultaneously determined during the screening. Taking beta2-adrenoceptor (β2AR) as a probe, this work created a strategy for screening GPCR ligands with simultaneous characterization of their downstream G protein binding responses associated with GTP. The strategy included (ⅰ) the design and expression of a protein miniature formed by β2AR and G protein α-subunit (Gαs) using circularly permuted HaloTag (cpHalo) as a flexible linker; (ⅱ) immobilization of the miniature onto silica gel by a click dehalogenation reaction; (ⅲ) systematic characterization of the immobilized miniature by fluorescent and chromatographic studies, and (ⅳ) simulating of ligand-induced β2AR-Gαs signaling cascade by chromatographic assays using GTP as an indicator. The immobilized miniature exhibited specificity to β2AR and Gαs antibodies and ligands. The specificity is stable at least within fifteen days with the variation less than 1%. The intrinsic activities of β2AR ligands were distinguished by the changes of GTP chromatographic behaviors on Gαs-cpHalo-β2AR column. Agonists strengthened the binding affinity and kinetics of GTP with Gαs, while antagonist did not give any effect on them. With the intrinsic activity evaluation, we believe, it will improve the attributes of chromatographic methods for drug discovery efforts with minimizing false-positive results.
It has been widely recognized that hole transporting materials (HTMs) play a key role in the rapid progress of perovskite solar cells (PVSCs). However, common organic HTMs such as spiro-OMeTAD not only suffer from high synthetic costs, but also usually require the additional chemical doping process to improve their hole transport ability, which unfortunately induces the terrible stability issue. Therefore, it is urgent to develop low-cost dopant-free HTMs for efficient and stable PVSCs. In this work, we have successfully developed a new class of efficient dopant-free fluoranthene-based HTMs (TPF1–5) with quite low lab synthetic costs by combining donor-acceptor and branched structure designs. The detailed structure-property study revealed that tuning the twisted arms at different substitution sites would regulate the intermolecular interactions and film-forming ability, thereby significantly affecting the performance of the HTMs. By applying these HTMs in conventional PVSCs, the dopant-free TPF1-based devices not only achieved the best efficiency of 21.76%, which is comparable to that of the doped spiro-OMeTAD control devices, but also showed much better operational stability, which maintained over 87% of the initial efficiency under maximum power point tracking after 1038 h.
Rhodium-catalyzed C4aryl−H activation and ring-retentive annulation of 2H-imidazoles with internal alkynes to build imidazo[5,1-a]isoquinolinium salts with high yields and broad scope has been disclosed. These novel salts serve as new full-color emissive fluorophores (433−633 nm), just by simply modifying the substituents on C3 and C4 positions of isoquinoline ring. Furthermore, these salts can undergo ring-opening C5aryl−H activation/annulation with a different alkyne to form non-symmetric and AIE-active 1,1′-biisoquinolines, where NH4OAc plays an indispensable role that accounts for Hofmann elimination and imine formation, leading to an unprecedented imine dance: cyclic imine → N-alkenyl imine → NH imine. The 15N labelling experiments indicate that the 2nd annulation includes two pathways: N-exchange (major) and N-retention (minor).
A novel and readily available binaphthyl-based fluorescent probe (S)-1 was designed and synthesized. (S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids, but also enantioselectively recognize histidine. Encouragingly, enantioselective imaging of histidine in cells was achieved for the first time by the probe (S)-1. These performances endowed it potential application in the chiral analysis of basic amino acids in asymmetric synthesis and cell imaging for diagnosis of diseases caused by racemization of histidine. Nuclear magnetic resonance (NMR) and mass spectrometry investigations suggested that different reaction extent of (S)-1 with l/d-histidine and different product structures generated the observed enantioselective fluorescent response. The molecular structures and thermodynamic stability of the complexes, formed from (S)-1 + Zn2+ and enantiomers of histidine, were calculated by Gaussian 16 based on density functional theory (DFT) to validate the above action mechanism.
A novel biodegradable material, Se@PLA, was designed and prepared via the selenization reaction of polylactic acid using NaHSe as the selenization reagent. This material shows excellent antibacterial activity (EC50 = 13.38 µg/mL) against Xanthomonas oryzae pv. Oryzae, which is a highly destructive pathogen responsible for rice bacterial blight. Se@PLA induces oxidative stress in bacteria, leading to the rupture of bacterial cell membranes and eventual death. Moreover, Se@PLA can significantly inhibit the motility of bacteria and is low toxic to soil and aquatic organisms. This work provides an effective method for preventing and controlling rice bacterial blight, and reveals the great potential of using Se@PLA as an alternative next generation plant bactericide.
Epilepsy, as a chronic neurological disease of the brain, is closely related to oxidative stress, and the peroxynitrite (ONOO−) significantly rise up in this event. Therefore, ONOO− is considered as a potential biomarker for early prediction of epilepsy. However, some potential diagnostic reagents for epilepsy are hindered by the blood-brain barrier (BBB). Meanwhile, “drug repurposing” is attracting a growing interest. Edaravone (EDA), as a first-line drug in the clinical treatment of cerebral ischemia, plays antioxidant roles in scavenging free radicals, promising potential antiepileptic activity. Thus, it is imperative to develop fluorescent probes for monitoring ONOO− fluctuations in the epileptic brain. Hence, we proposed a novel fluorescent probe with the thiocarbonate as the promising recognition unit for ONOO− and dicyanoisophorone derivative as the fluorophore. Moreover, by the “three-in-one” strategy, the introduction of trifluoromethyl into DCI-ONOO-3 can extend the emission wavelength of the fluorophore, shorten the response and increase lipophilicity. Consequently, DCI-ONOO-3 was used for monitoring ONOO− fluxes in brain of epileptic mice and evaluating the antiepileptic efficacy of EDA. It opens up a new way for the design of BBB permeable fluorescent probes, and provides a convincing new method for the diagnosis and treatment of epilepsy.
The adsorption of peroxymonosulfate (PMS) is crucial for PMS activation in the heterogeneous advanced oxidation processes. However, the investigation of PMS adsorption on the piezocatalysts still remains insufficient. In this work, bismuth oxychloride (BiOCl) nanosheets were prepared as the piezocatalysts for PMS activation under ultrasonic vibration to remove carbamazepine (CBZ) in aqueous solutions. Up to 92.5% of CBZ was degraded for 40 min in BiOCl piezo-activated PMS system with the reaction rate constant of 0.0741 min−1, being 1.63 times that of the sum of BiOCl piezocatalysis, BiOCl-activated PMS, and vibration-activated PMS. PMS adsorption on the surface of BiOCl was specifically studied by comparing the microscopic structure change of the fresh and used BiOCl. The results suggested that the piezoelectric field of BiOCl was able to promote the tight adsorption of PMS on the surface, thus facilitating the fast activation of PMS through electrons transfer to produce reactive species (HO•, SO4•−, O2•−, 1O2). This work presents an in-depth understanding for the role of piezoelectric effect on the adsorption and activation of PMS.
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