Latest ArticlesThe catalytic asymmetric dipolar cycloaddition reaction is efficient for the construction of various chiral valuable carbo- and heterocycles. Thus, the design and exploration of new dipoles and the subsequent control of their reactivity for various stereoselective cycloadditions are significant aspects of modern organic synthesis. Herein, we have developed a series of vinyl cyclic carbamates containing an oxazolidine-2,4–dione fragment and used them as reactive precursors for in situ generation of amide-based aza-π-allylpalladium 1,3-dipoles, which could be applied to asymmetric decarboxylative 1,3-dipolar cycloaddition with different types of dipolarophiles containing C=C, C=N, and C=O double bonds. This strategy provides an opportunity for the synthesis of previously unusual structures, such as highly functionalized optically pure pyrrolidin-2-ones, imidazolidin-4-ones, and oxazolidin-4-ones. This protocol also has significant features including wide substrate scope, mild reaction conditions, simple operation, and good to excellent results (70 examples, up to 99% yield, >20:1 dr and 99% ee). This unique method significantly expands the reaction range of the amide-based aza-π-allylpalladium 1,3-dipoles compared to the precedents.
Colorectal cancer is a common cancer worldwide. Traditional chemotherapeutic drugs often face limitations such as poor aqueous solubility and high systemic toxicity, which can lead to adverse side effects and limited therapeutic efficacy. In this study, a library of one kind of biodegradable and biocompatible polymer, leucine based-poly(ester amide)s (Leu-PEAs) was developed and utilized as drug carrier. The structure of Leu-PEAs can be tuned to alter their physicochemical properties, enhancing drug loading capacity and delivery efficiency. Leu-PEAs can self-assemble into nanoparticles by nanoprecipitation and load paclitaxel (PTX) with the diameter of ~108 nm and PTX loading capacity of ~8.5%. PTX-loaded Leu-PEAs nanoparticles (PTX@Leu-PEAs) demonstrated significant inhibition of CT26 cell growth in vitro. In vivo, these nanoparticles exhibited prolonged tumor accumulation and antitumor effects, with no observed toxicity to normal organs. Furthermore, blank Leu-PEAs nanoparticles also showed antitumor effects in vitro and in vivo, which may be attributed to the activation of the mammalian target of rapamycin (mTOR) pathway by leucine. Consequently, this biocompatible Leu-PEAs nano-drug delivery system shows potential as a promising strategy for colorectal cancer treatment, warranting further investigation.
Photodynamic therapy has been widely employed as an alternative strategy against bacterial infection. Molecular structure has a profound effect on the antibacterial ability of photosensitizers (PSs). Herein, we designed and synthesized a series of boron dipyrromethene (BODIPY)-based photosensitizers with different alkyl chain lengths, and then their antibacterial activities were compared. Among these BODIPYs, the BODIPY with octyl (BDP-8) exhibits the best antibacterial effect, while the antibacterial performance of BODIPY with dodecyl (BDP-12) is the worst. This work provides instructive information for further development of effective photodynamic antimicrobial agents.
Owing to the high spatiotemporal resolution, the second near-infrared (NIR-Ⅱ) imaging window can provide high imaging contrast with diminished tissue autofluorescence and suppressed photon scattering to pinpoint the locations for tumor surgery. Due to the unique optical properties and excellent fluorescence performance, quantum dots (QDs) are regarded as ideal nanoprobes for fluorescence-guided surgery (FGS). Moreover, QDs can be excited by a variety of light sources owing to the continuous and wide absorption ranges. Herein, light-emitting diode (LED) was used as the excitation source of QDs-based nanoprobes to realize FGS of tumor with high resolution. Since the LED light could irradiate a large region with consistent light intensity, signal distortion at the edge of imaging field was avoided. The signal intensity of the view edges under LED excitation can be improved by about 5 times compared to laser excitation. Therefore, more micro-vessels and smaller tumors (Vtumor < 5 mm2) could be detected, thus providing more precise guidance for tumor resection surgery.
The anti-oxidative characteristic and immunosuppressive microenvironment contribute to a high resistance of tumor to many treatments. In this work, a glutathione (GSH)-responsive metal-coordinated oxidative stress amplifier (designated as CuPA) is fabricated to suppress tumor growth through elevating the cellular level of reactive oxygen species (ROS) and eliminating M2 macrophages. Among which, cooper ion (Cu2+) is capable of coordinating with thioredoxin (Trx) inhibitor of PX-12 and signal transducer and activator of transcription 6 (STAT6) inhibitor of AS1517499 with the assistance of distearoyl phosphoethanolamine-PEG2000 (DSPE-PEG2000), which can extensively increase the stability to enhance drug delivery in vitro and in vivo. Furthermore, CuPA can upregulate intracellular ROS to cause tumor cell death through restraining Trx and degrading GSH. Also, CuPA-mediated STAT6 inhibition results in the elimination of M2 macrophage to reverse the immunosuppressive tumor microenvironment. Finally, the elevated oxidative stress and increased immune activation amplify the synergistic antitumor effect without causing obvious side effect. This work provides a new sight for synergistic tumor suppression through chemo-immunotherapy in consideration of the complex resistant tumor microenvironment.
The utilization of fungicides in plants is very low, emphasizing the need to improve their utilization rates. In this study, the fungicide dimethachlon (Dim) was encapsulated within hollow mesoporous silica (HMSNs), and a coating was formed on the HMSNs surface through the reaction of Na2CO3 and CaCl2, resulting in a pH-responsive delivery system named D/H@CaCO3, proven valuable in preventing sclerotinia diseases in romaine lettuce. When disease-infested romaine lettuce was treated with D/H@CaCO3, it degraded in the acidic microenvironment of Sclerotinia sclerotiorum (S. sclerotiorum), allowing for the pH-responsive release of Dim and effectively killing S. sclerotiorum. Moreover, the degraded CaCO3 coating releases CO2, which enhances the photosynthetic pigment contents, such as chlorophyll a, chlorophyll b, and carotenoids, in turn promoting plant growth. D/H@CaCO3 is biologically safe for plants and is environmentally friendly, as confirmed by assessments involving zebrafish and earthworms. Given their antifungal capabilities, the controlled release of fungicides offers potential for plant protection.
The insufficient F(III)/Fe(II) cycling rate resulted from high combination of photogenerated carriers severely hinders the photo-Fenton activity. In this work, 0 dimensional α-Fe2O3 nanoclusters decorated TiO2 heterojunction (FT-x) was prepared via in-situ phase transformation strategy. FT-200 exhibited the optimal photo-Fenton activity for 2,4-dichlorophenol degradation with the kinetic rate constant reaching 1.0806 min−1 under low H2O2 dosage (1 mmol/L), which was 126.1 and 202.8 times higher than that of TiO2 and α-Fe2O3. Radical quenching experiments and electron spin resonance spectra proved that ·OH was the leading reactive specie. The enhanced photo-Fenton activity was attributed to the accelerated F(III)/Fe(II) cycling rate induced by the direct Z-Scheme charge transfer mechanism. Benefiting from the abundant ·OH production, the dechlorinate ratios and mineralization ratios of multiple chlorophenol pollutants (2,4-dichlorophenol, 4-chlorophenol, 2,4,6-trichlorophenol) all exceeded 98%. The biotoxicity of chlorophenol wastewater was greatly reduced after the treatment by Light/H2O2/FT-200 system. Overall, this work constructed a low-cost and highly efficient photo-Fenton system for refractory organic wastewater treatment.
In view of widespread existence and toxicity, removal and detection of bisphenols is imperative to assess environmental risks and reduce harm to human health. Although many techniques have been reported, constructing fast and sensitive method remains a challenge. Herein, porous poly(divinylbenzene) polymer was synthesized in-situ on the Fe3O4 particles by means of distillation-precipitation polymerization and functioned as sorbents to extract bisphenols. Employing Fe3O4@poly(divinylbenzene) as sorbent, a magnetic solid-phase extraction coupling with liquid chromatography was developed to detect trace bisphenols in water. This method presented low detection limits (0.01–0.03 ng/mL), high enrichment ability (enrichment factor, 327–343), and good reproducibility. Moreover, the method showed satisfactory recoveries in the detection of lake water (80.60%-116.2%) and egg sample (75.17%-120.0%). Impressively, Fe3O4@PDVB has excellent adsorption capacity, which can realize rapid kinetic adsorption of bisphenols with equilibrium time all less than 10 s. The maximum adsorption capacities reached 1074.8, 1049.7, 1299.1 and 1329.5 mg/g for bisphenol F, bisphenol A, bisphenol B and bisphenol AF with Langmuir isotherm model. The adsorption mechanism of Fe3O4@PDVB to bisphenols was investigated and demonstrated that hydrophobic interactions played a key role, together with assistance of stacking interactions and hydrogen interactions. Overall, this work provides a promising sorbent material with ultra-fast and large adsorption capacities for extraction of bisphenols from water.
Bacterial endotoxin (a type of lipopolysaccharide, LPS) that acts as the strongest immune stimulant exhibits high toxicity to human health. The golden standard detection methods rely heavily on the use of a large amount of tachypleus amebocyte lysate (TAL) reagents, extracted from the unique blue blood of legally protected horseshoe crabs. Herein, a cost-effective distance-based lateral flow (D-LAF) sensor is demonstrated for the first time based on the coagulation cascade process of TAL induced by endotoxin, which causes the generation of gel-state TAL. The gelation process can increase the amount of trapped water molecules and shorten the lateral flow distance of the remaining free water on the pH paper. The water flow distance is directly correlated to the concentration of endotoxin. Noteworthy, the D-LAF sensor allows the detection of endotoxin with the reduced dosage of TAL reagents than the golden standard detection methods. The detection limit of endotoxin is calculated to be 0.0742 EU/mL. This method can be applied to the detection of endotoxin in real samples such as household water and clinical injection solution with excellent performance comparable to the commercial ELISA kit.
The chemical investigation into the EtOAc extract of the deep-sea-derived fungus Penicillium citrinum W22 yielded three unprecedented citrinin dimers, neo-Dicitrinols A–C (1–3) and a known one, penicitrinone A (4). Their structures were elucidated by extensive analysis of spectroscopic data, electronic circular dichroism (ECD) calculation, X-ray diffraction, and biogenetic consideration. neo-Dicitrinols A–C (1–3), bearing a tetramic acid unit, represent the first example of citrinin analogues as hybrid polyketide synthase-nonribosomal peptide synthase (PKS-NRPS) products. neo-Dicitrinol C (3) significantly inhibited renin-angiotensin system-selective lethal 3 (RSL3)-induced ferroptosis with a half maximal effective concentration (EC50) value of 21.6 µmol/L.
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