Yanmin Zhao,Xin Geng,Xinxin Shi,Yifei Guo,Yuanqiang Sun,Lingbo Qu,Zhaohui Li
Developing optical oxygen-sensitive nanoparticles with good biocompatibility and low cost to rapidly detect molecular oxygen in a signal turn-on mode is highly desirable. Herein, we present a phenylenediamine-derived carbon dot (CD), which has been found to display a fluorescence-switchable property, with fluorescence quenching by Na2S2O4 and fluorescence recovery triggered by O2. Because of this unique property, we directly employed the quenched CDs as a reversible probe for the fluorescence turn-on detection of molecular oxygen and found that this detection mode possessed a short response time of 12 s and high sensitivity. Moreover, this CD solution could be used as a writeable ink for the patterning of paper strips and security service without any loss in the fluorescence-switchable property. We thus achieved CD-based test strips for oxygen detection in vacuum packaging. This study not only provides a convenient, low-cost and practical way for oxygen detection but also reveals a fluorescence-switchable CD that will find its applications in numerous O2-involved fields.
The fabrication of efficient catalysts to reduce nitrogen (N 2 ) to ammonia (NH 3 ) is a significant challenge for artificial N 2 fixation under mild conditions. In this work, we demonstrated that the simultaneous introduction of oxygen vacancies (OVs) and Mo dopants into Bi 5 O 7 Br nanosheets can significantly increase the activity for photocatalytic N 2 fixation. The 1 mol% Mo-doped Bi 5 O 7 Br nanosheets exhibited an optimal NH 3 generation rate of 122.9 μmol g −1 h −1 and durable stability, which is attributed to their optimized conduction band position, suitable absorption edge, large number of light-switchable OVs, and improved charge carrier separation. This work provides a promising approach to design photocatalysts with light-switchable OVs for N 2 reduction to NH 3 under mild conditions, highlighting the wide application scope of nanostructured BiOBr-based photocatalysts as effective N 2 fixation systems.
Recreating the intricate enzymatic sites within in artificial materials poses a significant challenge due to the complex folding characteristics of enzymes. In this study, we designed a supramolecular catalyst by assembling intramolecularly folding G-quadruplex DNA with Fmoc-amino acid aggregates and Cu2+. This supramolecular material possesses active sites and catalytic functions that rely on copper clusters, mirroring the functionality of catechol oxidase. Experimental and theoretical simulations showed that Fmoc-amino acids interact with G-quadruplex DNA through groove binding, facilitating Cu2+ coordination to both components, thereby enhancing the oxidative catalysis of Cu2+ upon assembly. Our catalyst exhibited excellent tolerance to high temperature, varying ionic strength, and extended room-temperature storage in aqueous solutions. Moreover, our supramolecular complex effectively catalyzed the degradation of doxorubicin, a drug with a high affinity for the DNA component, demonstrating its potential for removing pharmacological pollutants. Additionally, by integrating a photoisomerizable azobenzene derivative as a ligand to the G-quadruplex DNA, we can switch the activity of the enzyme-mimetic catalyst between on and off states by adjusting the irradiation wavelength. This multicomponent approach offers a promising avenue for the design and engineering of active, adaptable supramolecular catalysts.
Yu Lili,Yao Lin,Li Li,Liu Shaojing,Jia Zhengxuan,Wu Di
The cationic photo-responsive polymeric micelles (mPEG-b-p(DEMA-co-MMA-CL)) with light-switchable cross-linker were designed and fabricated by atom transfer radical polymerization and quaternization. These micelles were well dispersed spherical with positive charge. The efficient release of encapsulated contents can be triggered by light irradiation. No significant toxicity was observed of copolymer and its photolysis residues at concentrations up to 250 μg/mL. The antitumor activity of camptothecin (CPT) in micelles demonstrated that light triggered the release of CPT, which dramatically improves the cytotoxicity after UV irradiation.
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