Latest ArticlesCorrosion of reinforcement induced by chloride invasion is extensively considered as the dominating deterioration mechanism of reinforced concrete (RC) structures, leading to serious safety hazards and tremendous economic losses. However, it still lacks well dispersive and cost-efficient nanomaterials to improve the anti-chloride-corrosion ability of RC structures. Herein, specific carbon dots (CDs) with high dispersity and low cost are deliberately designed, successfully prepared by hydrothermal processing, and then firstly applied to immensely enhance chloride binding performance of cement, thereby contributing to suppressing the corrosion of reinforcement. Specifically, the tailored CDs are composed of the carbon core with highly crystalline sp2 C structures and oxygen-containing groups connecting on the carbon core; The typical equilibrium test confirms that with respect to that of the blank cement paste, the chloride binding capacity of cement paste involving 0.2 wt% (by weight of cement) CDs is increased by 109% after 14-day exposure to 3 mol/L NaCl solution; according to comprehensive analyses of phase compositions, the chloride binding mechanism of CDs-modified cement is rationally attributed to the fact that the incorporation of CDs advances the formation of calcium silicate hydrate (C–S–H) gels and Friedel's salt (Fs), thus enormously enhancing the physically adsorbed and chemically bound chloride ions of cement pastes. This work not only firstly provides a novel high-dispersity and low-cost nanomaterial toward the durability enhancement of RC structures, but also broadens the application of CDs in the field of engineering, conducing to stimulating their industrialization development.
As a type of new carbon-based nanomaterials, carbon dots (CDs) possess exceptional optical properties, making them highly desirable for use in fluorescent sensors. However, the CDs with deep-red (DR) or near-infrared (NIR) emission have rarely been reported. In this work, we prepared deep-red emissive fluorine-doped carbon quantum dots (F-CDs) by introducing a precursor simultaneously containing fluorine and amidogen. The synergistic effect of nitrogen doping and D-π-A pattern production contributed to the maximum emission of F-CDs at 636 nm with an absolute quantum yield of 36.00% ± 0.68%. Moreover, we designed an F-CDs-based fluorescence assay to determine the content of hypochlorite (ClO−), with a limit of detection (LOD) as low as 15.4 nmol/L, indicating the high sensitivity of F-CDs to ClO−. In real samples, the F-CDs-based fluorescent sensor exhibited excellent sensitivity and selectivity in the detection of ClO−, with an error below 2%, suggesting their great potential in daily life. In cancer cell imaging, the F-CDs not only demonstrated high sensitivity to ClO− but also exhibited excellent mitochondria targeting, as evidenced by the high Pearson's correlation coefficient (PCC) of 0.93 in colocalization analysis. The work presented here suggests the great potential of replacing commercial dyes with F-CDs for highly specific mitochondria labeling and cell imaging.
Heterogeneous reaction of mineral aerosols and atmospheric polluting gases play an important role in atmospheric chemistry. In this study, the reactions of NO2 with or without SO2 mixture gas on the surface of α-Fe2O3 particles under dry conditions were studied. The effects of sodium dodecyl sulfate (SDS) and the heterogeneous reaction under both dark and UV irradiation conditions were investigated. The infrared spectrum analyzed by the two-dimensional correlation spectroscopy (2D-COS) was used to obtain the products formation sequences. The results showed that UV irradiation can promote the production of nitrate. The 2D-COS analysis indicated SDS changed the sequence order of nitrate and nitrite species during reactions. In oxidation conditions, the final product of heterogeneous reaction of NO2 and α-Fe2O3 was monodentate nitrate. Only the heterogenous reaction of NO2 and α-Fe2O3 containing SDS (FOS) without UV light, the final product was bidentate nitrate. SDS was the catalysis agent supply and photoresist to the system. With surface active compounds, the environmental lifetime of heterogeneous reactions between trace gases and aerosols extends. Surfactants, ultraviolet light, and the types of gases involved in the reaction all have complex effects on the aerosol aging process. This study provided a reference for subsequent heterogeneous reaction studies and the formation of aerosols.
The efficient conversion of CO2 into hydrocarbon fuels (CH4) with high selectivity is considered as a great challenge in photocatalysis owing to the multiple-electron transfer pathway and competitive H2 generation. Herein, we developed carbon dots (CDs)-modulated S-scheme heterojunction of CDs/NiAl-LDH@In2O3 (C-DH@IN) through a facile in-situ hydrothermal method. Thanks to the multi-shell nanotube structure, the C-DH@IN shows an enhanced CH4 evolution rate of 10.67 µmol h−1 g−1 and higher selectivity of CH4 (85.70%) compared with In2O3 and NiAl-LDH@In2O3 binary catalyst in the pure water without sacrificial agent. Electron spin resonance (ESR) and in situ Fourier transform infrared spectra verify that the constructed S-scheme heterojunction can possess the strong redox capability and the HCOO− and CH3O− as critical intermediates play an important role in selective CO2 reduction to generate CH4. Furthermore, CDs with superior photoabsorption can boost the electron transfer and absorb H+, thus improving the integration of H+ and CO2 molecule. Therefore, this work emphasizes a facile strategy to achieve efficient CO2-to-CH4 conversion based on construction of CDs-based heterojunction catalysts.
The biosecurity hazards caused by pathogenic fungus have been widely concerned. Given the long-term coexistence of eukaryotic pathogens and quorum sensing bacteria in different habitats in environments, we hypothesized that they have social interactions via signal molecules. In this work, we firstly discovered the well-known bacterial signal molecules play an adverse role in the cell morphology and metabolism in a model pathogen Trichosporon asahii. N-Tetradecanoyl-L-homoserine lactone (C14-HSL) was discovered to increase pathogen hazards of T. asahii, which limited mycelium by 52%, but enhanced cell aggregation by 93%. Higher fluorescence intensity of tryptophan (59%) and aromatic protein (2-fold) contents after the treatment of C14-HSL, indicating that aromatic proteins helped aggregate Trichosporon and showed hydrophobicity. Transcriptome analysis revealed that C14-HSL upregulated the shikimate pathway (above 1-fold) located in downstream of tricarboxylic acid cycle, which contributed to the synthesis of more aromatic proteins and the formation of larger flocs. The limited mycelial growth of T. asahii attributed to the up-regulated expressions of cell cycle process. The fungal transboundary response to bacterial C14-HSL was controlled by signal transduction pathways. This study provides new insights into the co-evolution of bacterial and pathogenic fungi in microecosystems.
Single atom catalysts (SACs) have been in the forefront of catalysts research because of their high efficiency and low cost and provide new ideas for development of renewable energy conversion and storage technologies. However, the relationship between the intrinsic properties of materials such as lattice thermal conductivity and catalysis remains to be explored. In this work, the lattice thermal conductivity of BN and graphene was calculated by ShengBTE. In addition, the adsorption properties of 3d-TM (TM = V, Cr, Mn, Fe, Co, Ni) on BN and graphene were investigated using first-principles methods, and it was found that Ni atom can form relatively stable SACs compared to other TMs. The molecular dynamics (MD) simulation and migration barrier of Ni loaded on BN and graphene were calculated. Our study found that graphene has higher thermal conductivity and is easier to form SACs than BN, but the SACs formed on BN surface have higher thermodynamic stability.
Immunosuppressive microenvironments present critical problems in clinical chemotherapy. To regulate the tumor immune microenvironment for enhancing antitumor effect, a combination of immune checkpoint inhibitors (ICIs) with chemotherapeutics has been applied clinically. In this study, miriplatin (MiPt), the lipidic derivative of 5-fluorouracil (Fu-OA), as well as the programmed death ligand 1 (PD-L1) target siRNA (siPD-L1) were integrated into Lip-Pt/Fu@siPD-L1 nanoparticles (NPs) for chemo-immunotherapy. In vitro results showed that Lip-Pt/Fu@siPD-L1 NPs could exhibit effective siRNA gene silencing and promote the phagocytosis of tumor cells by macrophages. Furthermore, in vivo results revealed that Lip-Pt/Fu@siPD-L1 NPs showed significantly higher anti-tumor efficiency than that of the physical mixing of MiPt, 5-fluorouracil, and Lip@siPD-L1 NPs (delivery of siPD-L1 by liposomes). The best anti-tumor efficiency of Lip-Pt/Fu@siPD-L1 NPs resulted from the synergistic immunotherapeutic effects of MiPt and siPD-L1 based on the inhibition of CD47 expression and the downregulation of PD-L1 in tumor cells, which elicited a robust anti-tumor immune response through the activation of macrophage phagocytosis and immune checkpoint inhibition. The Lip-Pt/Fu@siPD-L1 NPs provide a potential strategy for tumor chemo-immunotherapy.
Introducing heavy halogen atoms into organic small molecules is a practical strategy for efficient singlet oxygen (1O2) generation. Generally, bromine or iodine atoms are introduced on the aza-boron-dipyrromethene (aza-BODIPY) core, rather than on the periphery aryl rings for efficient 1O2 generation. Herein, an aza-BODIPY dye NBDPBr with unexpected bromination on the periphery aryl rings was synthesized for photoacoustic (PA) imaging-guided synergistic photothermal therapy (PTT) and photodynamic therapy (PDT) in tumor cells. Owing to unexcepted bromination at the periphery aryl rings, NBDPBr demonstrated an outstanding singlet oxygen quantum yield of 66% which was superior to similar brominated photosensitizers previously reported. After encapsulation with amphiphilic polymer F-127, hydrophilic NBDPBr nanoparticles (NPs) were fabricated and exhibited an excellent photothermal conversion efficiency (η) of 43.0% under 660 nm photoirradiation. In vivo PA imaging results demonstrated that NBDPBr NPs could specifically accumulate at tumor sites and realized the maximum tumor retention at 7 h post-injection. All the in vitro and in vivo results indicated the significant potence of NBDPBr with unexpected bis-bromination for PA imaging-guided synergetic PDT/PTT.
Molecular dielectric switches constitute a type of intelligent materials that are highly coveted for their distinctive advantages of switchable dielectric responses, lightweight, and mechanical flexibility. Two-dimensional (2D) hybrid perovskites have demonstrated excellent promise for assembling dielectric switches, in which the dynamic motions of organic moieties afford driving force to trigger switchable dielectric phase transition. Here, we successfully assembled a new lead-free hybrid double perovskite, (CHA)4CuBiBr8 (1, CHA = cyclohexylammonium), adopting a typical 2D structural motif, which shows dielectric anisotropy and bistable behaviors during the reversible phase transition near Tc = 378 K (the Curie temperature). That is, its dielectric constants could be switched and tuned between high-dielectric and low-dielectric states. Structure analyses reveal that the ordered-disordered transformation of the organic CHA+ moiety and distortion of inorganic framework account for its phase transition. This result will stimulate further exploration of molecular dielectric switches in this 2D environmentally friendly family.
The combination of horseradish peroxidase (HRP) and a fluorescence substrate has been attracting great interests in developing sensitive biochemical analysis and immunoassays. 10-Acetyl-3,7-dihydroxyphenoxazine (ADHP or Amplex red) is the most sensitive fluorogenic substrate known for HRP in current market, however, it suffers from some drawbacks, such as non-specific reactivity to carboxylesterase and limited fluorescence stability. In the present study, a novel HRP substrate 10-cyclopropylcarbonyl-dichloro-dihydroxyphenoxazine (AR-2), has been prepared, which exhibited improved sensitivity than ADHP in sensing HRP. Moreover, the fluorescence of AR-2/HRP demonstrated improved tolerance to physiological relevant pH fluctuation as compared to ADHP/HRP. Successful detection of uric acid/urate oxidase reaction indicated excellent application prospect of AR-2/HRP for monitoring H2O2-generating biochemical reactions. More interestingly, an enzyme-linked immunosorbent assay (ELISA) using AR-2 as the fluorescence reporter has been successfully used in detecting IgG against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from human serum samples. Overall, AR-2 exhibits improved performances over the commercial ADHP, which will be an ideal alternative to ADHP in HRP-based fluorescence biochemical analysis and immunoassays.
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