Carbon-doped flower-like Bi2WO6 decorated carbon nanosphere nanocomposites with enhanced visible light photocatalytic degradation of tetracycline

In search of a recyclable catalyst with synergistic adsorption and photocatalysis, unique composite photocatalysts of flower-like bismuth tungstate (Bi2WO6) and carbon nanospheres (CSs) were composited using a hydrothermal synthesis method (named CSs-Bi2WO6). Notably, based on the high visible light utilization and a reasonable band gap (2.53 eV), CSs-Bi2WO6 have good photocatalytic properties. For example, the composite with an optimized ratio (2% CSs-Bi2WO6) showed good adsorption and photocatalytic performance. Under simulated natural light conditions, the degradation rate of tetracycline (TC) by 2% CSs-Bi2WO6 was 84.6% in 60 min, which is nearly 25% higher than pure Bi2WO6. After five cycles, the observed barely decreased TC degradation rate of 2% CSs-Bi2WO6 confirmed the high cyclability and reproducibility of the photocatalyst. The total organic carbon estimation of the post-degradation reaction medium corresponded to 68.2% mineralization. Furthermore, we determined the photocatalytic reaction path by LC–MS, which confirmed that the composite catalyst could effectively degrade TC molecules into small molecules. It can be concluded that the catalyst has a broad application prospect in the field of wastewater treatment

Oxygenic Hybrid Semiconducting Nanoparticles for Enhanced Photodynamic Therapy

Photodynamic nanotheranostics has shown great promise for cancer therapy; however, its therapeutic efficacy is limited due to the hypoxia of tumor microenvironment and the unfavorable bioavailability of existing photodynamic agents. We herein develop hybrid core–shell semiconducting nanoparticles (SPN-Ms) that can undergo O₂ evolution in hypoxic solid tumor to promote photodynamic process. Such oxygenic nanoparticles are synthesized through a one-pot surface growth reaction and have a unique multilayer structure cored and coated with semiconducting polymer nanoparticles (SPNs) and manganese dioxide (MnO₂) nanosheets, respectively. The SPN core serves as both NIR fluorescence imaging and photodynamic agent, while the MnO₂ nanosheets act as a sacrificing component to convert H₂O₂ to O₂ under hypoxic and acidic tumor microenvironment. As compared with the uncoated SPN (SPN-0), the oxygenic nanoparticles (SPN-M1) generate 2.68-fold more ¹O₂ at hypoxic and acidic conditions under NIR laser irradiation at 808 nm. Because of such an oxygen-evolution property, SPN-M1 can effectively eradicate cancer cells both in vitro and in vivo. Our study thus not only reports an in situ synthetic method to coat organic nanoparticles but also develops a tumor-microenvironment-sensitive theranostic nanoagent to overcome hypoxia for amplified therapy

Unexpected selective alkaline periodate oxidation of chitin for the isolation of chitin nanocrystals

Periodate oxidation reaction occurring directly on chitin has been neglected in polysaccharide chemistry so far. Herein, we present the first direct alkaline periodate oxidation of chitin, which demonstrates at the same time a novel approach for the preparation of chitin nanocrystals (ChNCs). This oxidation is based on an unprecedented selective reaction of non-ordered domains of chitin by the dimeric orthoperiodate ions (H₂I₂O₁₀⁴⁻) as the major species in alkaline surroundings. Nearly 50 wt% of non-ordered regions are dissolved after sequential accelerated partial deacetylation, periodate oxidation and β-alkoxy fragmentation, which allows the isolation of up to 50 wt% of uniform anisotropic zwitterionic ChNCs