Latest ArticlesThe reactive oxygen species (ROS) generation efficiency is always limited by the extreme tumor microenvironment (TME), leading to unsatisfactory antitumor effects in photodynamic therapy (PDT). As a promising gas therapy molecule, nitric oxide (NO) is independent of oxygen and could even synergize ROS to enhance the therapeutic effect. However, the short half-life, instability, and uncontrollable release of exogenous NO limited the application of tumor synergistic therapy. Herein, we reported a novel kind of red-emissive carbon dots (CDs) that was capable of lysosome-targeted and light-controlled NO delivery. The CDs were synthesized by using metformin and methylene blue (MB) via a hydrothermal method. The obtained metformin-MB CDs (MMCDs) exhibited a higher 1O2 quantum yield and NO generation efficiency under light emitting diode (LED) light irradiation. Noteworthily, the 1O2 could further in situ oxidize NO into peroxynitrite anions (ONOO−), which own the higher cytotoxicity against cancer cells. Cell experiments indicate that MMCDs could destruct lysosome membrane integrity and kill almost 80% of HepG2 cells under light irradiation while very low cytotoxicity in the dark. Moreover, MMCDs significantly decreased tumor volume and weight after phototherapy in hepatoma HepG2-bearing mice. Our study provides a new strategy for light-controlled NO generation as well as precise lysosome-targeting for enhancement of PDT efficiency.
Cancer cell spheroids (CCS) are a valuable three-dimensional cell model in cancer studies because they could replicate numerous characteristics of solid tumors. Increasing researches have used matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate the spatial distribution of endogenous compounds (e.g., lipids) in CCS. However, only limited lipid species can be detected owing to a low ion yield by using MALDI. Besides, it is still challenging to fully characterize the structural diversity of lipids due to the existence of isomeric/isobaric species. Here, we carried out the initial application of MALDI coupled with laser-postionization (MALDI-2) and trapped ion mobility spectrometry (TIMS) imaging in HCT116 colon CCS to address these challenges. We demonstrated that MALDI-2 is capable of detecting more number and classes of lipids in HCT116 colon CCS with higher signal intensities than MALDI. TIMS could successfully separate numerous isobaric/isomeric species of lipids in CCS. Interestingly, we found that some isomeric/isobaric species have totally different spatial distributions in colon CCS. Further MS/MS imaging analysis was employed to determine the compositions of fatty acid chains for isomeric species by examining disparities in signal intensities and spatial distributions of product ions. This work stresses the robust ability of TIMS and MALDI-2 imaging in analyzing endogenous lipids in CCS, which could potentially become powerful tools for future cancer studies.
Cultural relics have their unique artistic, cultural and historical value, and the protection of important cultural relics is conducive to the inheritance of historical culture. As a kind of cementing agent and binder commonly seen in cultural relics protection, epoxy resin is widely used in the bonding and consolidation of various materials in cultural relics, which has important practical application value. In this review, a systematic classification of commonly used epoxy resins, including their molecular structures, synthesis reactions and properties are provided, the problems and solutions of epoxy resin in cultural relics protection are summarized. The solutions are classified into three aspects: functional epoxy resin, blending modification, and other modification. Representative application examples of epoxy resin are listed in the field of cultural relics protection, and the development direction of epoxy resin in cultural relics protection in the future is proposed, which provides useful guidance for the modification of epoxy resin and its application in cultural relics protection in the future.
Hydrogen has emerged as a promising environmentally friendly energy source. The development of low-cost, highly active, stable, and easily synthesized catalysts for hydrogen evolution reactions (HER) remains a significant challenge. This study explored the synthesis of nitrogen-doped MXene-based composite catalysts for enhanced HER performance. By thermally decomposing RuCl3 coordinated with melamine and formaldehyde resin, we successfully introduced nitrogen-doped carbon (NC) with highly dispersed ruthenium (Ru) onto the MXene surface. The calcination temperature played a crucial role in controlling the size of Ru nanoparticles (Ru NPs) and the proportion of Ru single-atom (Ru SA), thereby facilitating the synergistic enhancement of HER performance by Ru NPs and Ru SA. The resulting catalyst prepared with a calcination temperature of 600 ℃, Ti3C2Tx-N/C-Ru-600 (TNCR-600), exhibited exceptional HER activity (η10 = 17 mV) and stability (160 h) under alkaline conditions. This work presented a simple and effective strategy for synthesizing composite catalysts, offering new insights into the design and regulation of high-performance Ru-based catalysts for hydrogen production.
One of the largest subfamilies within the famous Daphniphyllum alkaloid family is made up of the yuzurimine-type (or macrodaphniphyllamine-type) alkaloids. Their complex aza-polycyclic caged structures, several contiguous stereogenic centers, and vicinal all-carbon quaternary centers make these alkaloids formidable challenge for synthetic chemists. Recently, synthesis of these alkaloids has received extensive attention from our community. Herein, we wish to report the total synthesis of C14–epi-deoxycalyciphylline H, a putative member of yuzurimine-type alkaloid subfamily. Key transformations employed in our approach include an intramolecular Prins reaction and a Pd-catalyzed enyne cycloisomerization. In addition, synthesis of a daphnezomine L-type alkaloid, paxdaphnidine A, was also studied.
RNA modifications have been involved in numerous biological processes, and aberrations of these modifications are tightly associated with various diseases including cancer. Herein, we developed graphene-based solid-phase extraction and robust ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with stable isotope-dilution for simultaneous enrichment and accurate determination of 17 modified nucleosides in human urine. We found graphene could effectively adsorb various modified nucleosides in human urine samples. With this method, we identified and quantified these modified nucleosides in urine samples collected from lung cancer patients and healthy controls. We revealed that the levels of 12 modified nucleosides were all diminished in urine from lung cancer patients, compared with healthy controls. It is worth noting that we demonstrated, for the first time, the presence of 5,2′-O-dimethyluridine (m5Um) in human urine. Together, we established a robust analytical method for simultaneous determinations of 17 modified nucleosides in human urine, and our results revealed a close correlation between the concentrations of urinary modified nucleosides and the occurrence of lung cancer, implying the potential applications of these modified nucleosides as noninvasive biomarkers for the early detection of lung cancer. Moreover, this study will stimulate future investigations on the regulatory roles of RNA modifications in the initiation and progression of lung cancer.
Schiff base metal complexes are of great importance in pharmaceutical science owing to their unique chemical properties, which enable them to exhibit diverse biological activities such as anti-bacterial, anti-oxidant, anti-inflammatory, and anti-tumor properties. Furthermore, Schiff base metal complexes can serve as reagents and catalysts in chemical reactions. This review aims to provide an overview of our recently published studies on Cu(Ⅱ) and Pd(Ⅱ) complexes derived from proline Schiff base ligands. We also discuss the potential applications of these metal complexes in the fields of antibacterial and chiral resolution.
While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons (PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B2S2 and Syn-B2S2, as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10−3 cm2 V−1 s−1 were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.
Photocatalytic conversion of CO2 into small-molecule chemical feedstocks can meet the growing demand for energy and alleviate the global warming. Herein, a p-n ZnO@CDs@Co3O4 heterojunction with sandwich structure was constructed by calcination method of self-assembled ZIF-8@CDs@ZIF-67. The ZnO@CDs@Co3O4 with well-defined interfacial structure exhibited the significantly enhanced photocatalytic CO2 reduction activity, and the optimal catalyst indicated the (CO + CH4) evolution rate of 214.53 µmol g−1 h−1 under simulated solar light, which was superior to ZnO, Co3O4 and binary ZnO@Co3O4. The internal cavity, exposed active sites, multiple interfaces and constructed p-n heterojunction can facilitate the light harvesting and photoexcited electron transfer. Besides, after introduction of CDs placed in the middle layer between ZnO and Co3O4, CDs with excellent photoelectric property further promoted charge separation and migration. This work represents an appealing strategy to construct well-defined photocatalysts for boosting CO2 photoreduction.
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