Latest ArticlesAzulene is a promising building block for creating innovative polycyclic aromatic hydrocarbons. This study involved the construction of three nonalternant isomers of pentacene by fusing two azulene units, named Az-PH1/2/3. Az-PH1 was initially developed through the rhodium(II)-catalyzed cyclization of bis(N-tosylhydrazone)s. Intriguingly, Az-PH1 was also unexpectedly obtained during a nickel(0)-catalyzed one-step tandem reaction. We investigated the optical and electrochemical properties, aromaticity, and photo-oxidative stability of Az-PH1, comparing it with the well-known pentacene using density functional theory, electrochemical, and photophysical tests. Our results showed that the azulene-fusing strategy resulted in a molecule with narrow optical bandgaps (2.046 eV) and a long half-life time under ambient air conditions.
Mechanochromophores based on bichromic molecular switches, such as bis-naphthopyanes, allow multimodal mechanochromic behavior beyond the typical binary response from single chromophores, which is important for distinguishing between multiple stress states through discrete changes in color. Spontaneously generated persistent and distinguishable multi-colors from activated bis-naphthopyanes remain challenging. And the versatility of bis-mechanophore design for advanced optical molecular systems and the fundamental insights into the corresponding mechano-reactivity are not enough. Here, we identify a dihydroanthracene bridged bis-naphthopyrans as a multimodal mechanochromophore in polymers. Bridging two pyrans with the sterically constrained dihydroanthracene is helpful to control the steric effect for the favorable formation of a distinctly appreciable bis-merocyanine (bis-MC) product. By varying the length of the polymer chains, the force delivered to the mechanophore is modulated, resulting in a gradient change in the relative distribution of two distinctly colored MC products and a multicolor mechanochromism. Mechanical activation of this bis-naphthopyanes proceeds via a mechanistically distinct pathway compared to the photochemical process. In addition, the bulk films can also achieve pronounced color changes when subjected to mechanical force. This study thus further expands the molecular diversity of mechanochromophores and tune the multimodal switch properties of bis-naphthopyrans based polymers.
Covalent adaptable networks (CANs), which share the properties of both thermosets and thermoplastics at the same time, are desirable for many applications. Introducing bulky substituents is a feasible way to design dynamic covalent bonds for constructing CANs, as evidenced by the successful implementation in CANs based on hindered urea bonds (HUBs). However, the dynamicity induced by introducing bulky substituents always come with low bond energy, resulting in low mechanical strength and poor stability of the CANs. Herein, we designed a novel hindered urethane bond, which is weak in thermodynamic (Keq = 1701.23 L/mol at 25 ℃) and inert in kinetic at low temperature, but stable in thermodynamic (Keq = 1.54 × 104 L/mol at 100 ℃) and active in kinetic at high temperature (k-1 = 0.105 h−1 at 80 ℃ and 0.315 h−1 at 120 ℃). As a result, the polyurethane based on it exhibits high mechanical properties (with Youngs' modulus of 1011 ± 29 MPa and flexible modulus reached 1833 ± 50 MPa) and excellent reversibility (can be reprocessed at 60 ℃ under 100 kPa in 30 min and completely healed at 40 ℃ in 10 min). Moreover, unlike to many CANs based on hindered urea bonds, our dynamic polyurethanes are highly stable in humid environment or even water solutions due to the slow hydrolysis kinetics. Such high-performance dynamic polyurethane polymers are attractive for many applications.
Microcystins (MCs), a family of cyclic heptapeptide cyanotoxins, exists in aquatic environment where cyanobacterial bloom happens, which will accumulate in aquatic organisms and transfer through the food chain to higher trophic levels, posing a health risk to both animals and human bodies. Among various MCs, Microcystin-LR (MC-LR) is worthiest studied for its strong toxicity, ubiquity and widespread. Here in this work, iminodiacetic acid (IDA) decorated magnetic mesoporous silica (mSiO2) nanocomposites (Fe3O4@mSiO2-IDA) were facilely synthesized which possessed the merits of large surface area (188.21 m2/g), accessible porosity (2.66 nm), excellent hydrophilicity and rapid responsiveness to magnetic field. Then the composites were successfully employed to the removal process of Microcystin-LR in real water samples followed by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, achieving the removal efficiency above 92.5% even after ten recycles of the composites. It provided a potential method for removing MC-LR in aqueous environment with high effectiveness, lower costs and less secondary contamination.
The galactomannan from Antrodia cinnamomea (AC) is characterized as one of the important bioactive components that exhibits potential immunostimulatory propriety. The biological function of its corresponding oligosaccharide fragments has not been revealed yet. In this study, we reported the first chemical synthesis of the series of oligosaccharide fragments related to AC galactomannan via the convergent glycosylation strategy. The preliminary immunological evaluation of these synthesized AC oligosaccharides disclosed that the backbone tetrasaccharide 1d showed the best immunomodulatory ability on enhancing proliferation, phagocytosis and cytokines secretion of Raw264.7 macrophages in vitro, indicating its immense potential as an immunostimulant candidate.
As the most common pathological type of nephrotic syndrome, membranous nephropathy (MN) presents diversity in progression trends, facing severe complications. The precise discrimination of MN from healthy people, other types of nephrotic syndrome or those with therapeutic remission has always been huge challenge in clinics, not to mention comprehensive individualized monitoring relied on minimally invasive molecular detection means. Herein, we construct a functionalized pore architecture to couple with machine learning to aid all-round peptidome enrichment and data profiling from hundreds of human serum samples, and finally establish a set of defined peptide panel consisting of 12 specific feature signals. In addition to the realization of above-mentioned precise discrimination with more than 97% of sensitivity, 88% of accuracy and f1 score, the simultaneously comprehensive individualized monitoring for MN can also be achieved, including conventionally screening diagnosis, congeneric distinction and prognostic evaluation. This work greatly advances the development of peptidome data-driven individualized monitoring means for complex diseases and undoubtedly inspire more devotion into molecular detection field.
Sulfydryl-contained (-SH) substances including hydrogen sulfide (H2S), cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) play crucial roles in living systems, and their variations are closely associated with various diseases. Herein, we developed a near-infrared intramolecular charge transfer (ICT) based fluorescent probe Y-NBD, achieving detection of Cys/Hcy and H2S with different fluorescent signals (green-red for Cys/Hcy, red for H2S), large Stokes shifts (~100/105 nm or 191 nm) and high signal-background-ratio, but not responding to GSH. Y-NBD was successfully applied to image exogenous/endogenous Cys/Hcy and H2S in various living cancer cells (HeLa, A549, and HepG2) and in zebrafish. It not only visualized the transformation pathway of several thiols in HepG2 cells but also verified that the intestine is the main site for the activation and metabolism of Y-NBD in zebrafish, as well as realized to evaluate the degree of drug-induced liver injury. This work provides a promising tool for imaging Cys/Hcy and H2S in living systems and shows great potency in evaluating drug-induced liver injury and its treatment.
Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults. The precise identification and distinction of GBM heterogeneity from surrounding brain parenchyma at the cellular level and even at the tissue level are important for GBM therapy. In this study, GBM cells are distinguished from normal astrocytes and non-central nervous system (CNS) tumor cells by surface-enhanced Raman scattering (SERS) based on gold nanoshell (SiO2@Au) particles and support vector machine (SVM) algorithm. In addition, the gold nanoisland (AuNI) SERS substrates are further developed and explored for accurate detection of GBM at the tissue level. The distinction between glioma and trauma tissues, identification of different tumor grades, and IDH mutation are realized with the assistance of orthogonal partial least squares discriminant analysis (OPLS-DA) in a rapid, non-invasive, and convenient method. The results show that the developed SERS-based analytical method has the potential for practical application for the detection of GBM at the single-cell and tissue levels and even for real-time intraoperative diagnosis.
The 2-hydroxy-4-methoxybenzyl (Hmb) backbone modification can prevent amide bond-mediated side-reactions (e.g., aspartimide formation, peptide aggregation) by installing the removable Hmb group into a peptide bond, thus improving the synthesis of long and challenging peptides and proteins. However, its use is largely precluded by the limited Hmb's installation sites. In this report, an improved installation of Hmb (iHmb) method was developed to achieve the flexible installation and the convenient removal of Hmb. The iHmb method involves two critical steps: (1) oxidative diazotization of the readily installed 2-hydroxy-4-methoxy-5-amino-benzyl (Hmab) to give 2-hydroxy-4-methoxy-5-diazonium-benzyl (Hmdab) by combining soamyl nitrite (IAN)/HBF4, and (2) reductive elimination of Hmdab to give the desired Hmb by 1,2-ethanedithiol (EDT). The iHmb method enables the installation of Hmb at any primary amino acid including the highly sterically hindered amino acids (e.g., valine and isoleucine). The practicality and utility of the iHmb method was demonstrated by one-shot solid-phase synthesis of a challenging aspartimide-prone peptide, the mirror-image version of a hydrophobic peptide and a long-chain peptide up to 76-residue. Furthermore, the iHmb method can be utilized to facilitate chemical protein ligation, as exemplified by the synthesis of the single-spanning membrane protein sarcolipin. The iHmb method expands the toolkit for peptide synthesis and ligation and facilitates the preparation of peptides/proteins.
In September 2018, we proposed the cutting-edge concept of "Beyond Limits Manufacturing" (BLM). BLM technology is based on the three-dimensional inner engraving or precise outer engraving of ultra-fast laser, to invent micro/nano scale flow chips or devices, which makes it possible for the microform, integration, economy, safety, high efficiency, green and intelligence of research, development and manufacturing process, so as to realize transformational manufacturing in the era of Industry 4.0. In this paper, we reviewed the representative results we made in the field of micro/nano flow chemistry during the implementation of the BLM major project (December 2019 to August 2023), and discussed its application prospects in micro/nano flow chemistry.
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