Latest ArticlesPoly(butylene adipate-terephthalate) (PBAT), as one of the most common and promising biodegradable plastics, has been widely used in agriculture, packaging, and other industries due to its strong biodegradability properties. It is well known that PBAT suffers a series of natural weathering, mechanical wear, hydrolysis, photochemical transformation, and other abiotic degradation processes before being biodegraded. Therefore, it is particularly important to understand the role of abiotic degradation in the life cycle of PBAT. Since the abiotic degradation of PBAT has not been systematically summarized, this review aims to summarize the mechanisms and main factors of the three major abiotic degradation pathways (hydrolysis, photochemical transformation, and thermochemical degradation) of PBAT. It was found that all of them preferentially destroy the chemical bonds with higher energy (especially C-O and C=O) of PBAT, which eventually leads to the shortening of the polymer chain and then leads to reduction in molecular weight. The main factors affecting these abiotic degradations are closely related to the energy or PBAT structure. These findings provide important theoretical and practical guidance for identifying effective methods for PBAT waste management and proposing advanced schemes to regulate the degradation rate of PBAT.
Surface with well-defined components and structures possesses unique electronic, magnetic, optical and chemical properties. As a result, surface chemistry research plays a crucial role in various fields such as catalysis, energy, materials, quantum, and microelectronics. Surface science mainly investigates the correspondence between surface property and functionality. Scanning probe microscopy (SPM) techniques are important tools to characterize surface properties because of the capability of atomic-scale imaging, spectroscopy and manipulation at the single-atom level. In this review, we summarize recent advances in surface electronic, magnetic and optical properties characterized mainly by SPM-based methods. We focus on elucidating the π-magnetism in graphene-based nanostructures, construction of spin qubits on surfaces, topology properties of surface organic structures, STM-based light emission, tip-enhanced Raman spectroscopy and integration of machine learning in SPM studies.
The demand for enhanced optical properties in advanced fluorescence technologies has driven research into the structure-property relationship of fluorophores. In this paper, we use naphthalene fluorophores NaDC-Aze and PhDO-Aze as a case study to emphasize the pivotal role of cross conjugation in tuning the optical structure-property relationship. NaDC-Aze and PhDO-Aze, formed by hybridizing two distinct conjugated systems in a single naphthalene molecule, exhibit spectral characteristics from both conjugated systems. Experimental data and theoretical calculations demonstrate the coexistence of two electron-delocalization systems in a cross-conjugation manner in both NaDC-Aze and PhDO-Aze. The cross-conjugation fluorophores exhibit high brightness, large Stokes shift, and a broad absorption wavelength range by combining distinct spectral properties from its parent fluorophores. These spectral properties will be advantageous for certain applications (i.e., panchromatic absorption in organic solar cells, and fluorophores compatible with a wide range of excitation wavelengths).
The treatment of skin wounds, especially chronic wounds, remains a critical clinical challenge and places a heavy burden on patients and healthcare systems. In recent years, the engineering strategy of using biomaterial-assisted exosomes has emerged as a powerful tool for skin repair. Compared to treatments such as debridement and regular dressing changes, the design of biomaterial-assisted exosomes not only maintains the bioactivity of exosomes at the wound site but also provides an appropriate microenvironment for the repair of complex tissues, thereby accelerating wound healing. This review systematically introduces the general characteristics of exosomes and their functions in skin wound healing, highlights recent advances in classification of natural exosomes and engineering methods which enriching their functions in intercellular communication. Then, various emerging and innovative approaches based on biomaterials delivery of exosomes are comprehensively discussed. The review seeks to bring an in-depth understanding of bioactive dressings based on exosomes therapeutic strategies, aiming to facilitate new clinical application value.
Aflatoxins B1 (AFB1) contamination in agro-food holds great threaten to human and animal health. Conventional test strips for rapid AFB1 visualized monitoring remains challenged by improvement of sensitivity and matrix interference resistance. In this case, we developed a portable electrochemiluminescence (ECL) imaging test strip with dual-signal outputs for AFB1 quantification in corn samples. Ru-PEI@SiO2@Au nanospheres were synthesized for bonding with anti-AFB1 antibody and then colorimetrical signal-reported on test line through the capillary flow at strips. Meanwhile, ECL imaging signal of the constructed carbon-ink-based working electrode on polyvinyl chloride substrate of strips was exported under an applied potential of 1.25 V. The whole ECL test strips not only endowed convenient colorimetric responses but guaranteed quick-witted ECL image distinguishment even at extremely low AFB1 content. The detection limit of this ECL imaging-integrated mode was 10-fold lower than that of only colorimetric mode. Furthermore, satisfactory selectivity, reliability and practicability of the as-proposed ECL test strips were demonstrated. This work offered a promising platform for on-site, accurate and sensitive detection of pollutants in foods.
Osteoarthritis (OA) is the most prevalent joint disease and icariin is a promising drug for its treatment. However, the clinical use of icariin is hindered by poor water solubility, low bioavailability, and non-specific release and biological distribution. Herein, sulfonated azocalix[4]arene (SAC4A) with enhanced water solubility, recognition capacity, and designed responsiveness was used to improve the efficiency of icariin for OA therapy. SAC4A, a macrocycle with well-defined molecular weight and structure, could encapsulate and enhance water solubility of various drugs. In addition, SAC4A enables hypoxia-responsive release of loaded drug. Compared with icariin treatment, supramolecular complex icariin@SAC4A significantly relieved OA symptoms of rats, including more regular bone morphology and structure, and lower degree of cartilage damage. Moreover, the supramolecular formulation demonstrated various advantages, including easy preparation, hypoxia-triggered release, and small size that conducive to drug penetration.
Ag2CO3-promoted dehydroxymethylative fluorination of aliphatic alcohols has been achieved with Selectfluor as both oxidant and fluorine source. The reaction involves β-fragmentation of primary alkoxy radicals, followed by the fluorination of the resulting C-centered radical intermediates. The transformation proceeds under mild reaction conditions and exhibits a broad substrate scope, thus opening up a new entrance to the synthesis of fluorinated constructs including α-fluoroimides and 1-fluoroalkyl benzoates as well as secondary and tertiary alkyl fluorides like versatile 2-fluoro-2-alkyl 1,3-propandiol derivatives. The divergent functionalization of the obtained α-fluoroimides enables an efficient access to amine derivatives through C–F bond activation under the action of BF3·OEt2.
Selenium is one of the important trace elements in the human body. Its deficiency will directly affect human health. With people's attention to health, the content of selenium in food has gradually attracted attention. However, detecting selenium compounds in complex samples remains a challenge. In this work, we built an online heating-reaction device. This device combines the electrospray extraction ionization mass spectrometry (EESI-MS) with the heating reaction device, which can simultaneously detect various selenium compounds in complex liquid samples. Under acidic conditions, the sample was heated and catalyzed by a heating reaction device, so that the SeO32− and O-phenylenediamine (OPD) could generate 1,3-dihydro-2,1,3-benzoselenadiazole. Based on the above reactions, we can detect organic selenium, inorganic selenium and other compounds in liquid samples by organic mass spectrometry. In this experiment, we determined the content of three forms of selenium: selenomethionine (SeMet), l-selenocystine (SeCys(2)), and sodium selenite. The calibration curves for SeMet, SeCys(2), and sodium selenite showed strong linearity within a range of 0.50–50.00 µg/L. The limits of detection (LOD) for the three compounds were 0.22, 0.27, and 0.41 µg/L, respectively. The limits of quantification (LOQ) were 0.68, 0.81, and 1.23 µg/L, respectively. Spiked recoveries at three levels ranged from 98.8% to 106.1%. In addition, this method can simultaneously detect three selenium compounds and three other specific chemical components in tea infusion samples, providing a rapid and efficient method for identifying tea quality.
Metal complexes hold significant promise in tumor diagnosis and treatment. However, their potential applications in photodynamic therapy (PDT) are hindered by issues such as poor photostability, low yield of reactive oxygen species (ROS), and aggregation-induced ROS quenching. To address these challenges, we present a molecular self-assembly strategy utilizing aggregation-induced emission (AIE) conjugates for metal complexes. As a proof of concept, we synthesized a mitochondrial-targeting cyclometalated Ir(III) photosensitizer Ir-TPE. This approach significantly enhances the photodynamic effect while mitigating the dark toxicity associated with AIE groups. Ir-TPE readily self-assembles into nanoaggregates in aqueous solution, leading to a significant production of ROS upon light irradiation. Photoirradiated Ir-TPE triggers multiple modes of death by excessively accumulating ROS in the mitochondria, resulting in mitochondrial DNA damage. This damage can lead to ferroptosis and autophagy, two forms of cell death that are highly cytotoxic to cancer cells. The aggregation-enhanced photodynamic effect of Ir-TPE significantly enhances the production of ROS, leading to a more pronounced cytotoxic effect. In vitro and in vivo experiments demonstrate this aggregation-enhanced PDT approach achieves effective in situ tumor eradication. This study not only addresses the limitations of metal complexes in terms of low ROS production due to aggregation but also highlights the potential of this strategy for enhancing ROS production in PDT.
Recently circularly polarized luminescence (CPL) materials have attracted significant interest. Introducing reversible dynamic property to these materials has been a key focus in cutting-edge fields, such as in high-level information encryption. Here, we provided a novel and general strategy involving handedness-selective filtration and ground-state chiral self-recovery (CSR) in double film system to address this issue. Based on this strategy, we achieved CPL switch through the reversible modulation of ground-state chirality including absorption and scattering circular dichroism (CD) signals over the full UV-visible wavelength range (365-700 nm) in a single azobenzene polymer (PAzo) film. More importantly, by flexibly changing the type of fluorescent films, it is convenient to achieve general excited-state CSR, that is reversible switching of full-color including ideal white (CIE coordinate (0.33, 0.33)), as well as room-temperature phosphorescent CPL. All these CPL signals without almost any intensity decay after three cycles of on-and-off switching. Experimental results indicated that the trans-cis isomerization and ordered rearrangement of azobenzene units in PAzo film were the fundamental reasons for realizing CPL switching. Finally, based on this system we achieved dynamic visual encryption and decryption process including multiple decryption methods. This study provides an effective method for constructing a universally applicable chiroptical switch in excited state.
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