Lianying Lu,Guohong Wang,Ziwei Xiong,Zifei Hu,Yuwei Liao,Juan Wang,Jun Li
A heterojunction of plasmonic Ag particles on Ti 3+ -doped macro-/meso-porous TiO 2 framework consisting of parallel microchannels, denoted as Ag/TiO 2- x , has been fabricated by a simple microwave-assisted process employing vitamin C as the reducing agent for forming TiO 2- x framework followed by photochemical deposition of Ag particles. Charge transport and recombination processes were detected through transient photocurrent responses. The visible-light photocatalytic hydrogen production rate and the apparent reaction rate constant of RhB photodegradation with 3%-Ag/TiO 2- x catalyst are about 5.3 and 14.0 fold higher than those with the pristine macro-/meso-porous TiO 2 framework, respectively. A mechanism based on the synergistic effects of Ag plasmonics and Ti 3+ -doping at the Ag/TiO 2- x heterojunction is proposed, which consistently explains the high photocatalytic performance in hydrogen evolution and the improved photocatalytic decomposition of RhB under visible light. This study demonstrates the effective route to synthesize new heterojunction photocatalytic materials with multifunctional properties using low-cost and rapid microwave processes.
The effective treatment for periodontitis is to completely and sustainedly eradicate the bacterial pathogens from the complex periodontal pockets. Local sustained-release antibiotics as a complementary treatment after scaling and root planning can sustainedly combat bacterial pathogens in the periodontal pockets to help treat the disease, but the increasing concern of bacterial resistance limits its future use. Here, we reported a local antibacterial system based on microsized multifunctional Ag–TiO2–x encapsulated in alginate (ATA) microspheres. We confirmed that ATA displayed strong photothermally enhanced dual enzyme-mimicking (peroxidase-like and catalase-like) activities and weak photocatalytic activity under 808 nm near-infrared (NIR) irradiation, which could boost the generation of reactive oxygen species (ROS) and O2 in the presence of low-level H2O2. As a result, the ATA/H2O2/NIR system exhibited efficient antibacterial activity against Porphyromonas gingivalis and Streptococcus gordonii in both planktonic and biofilm forms. With the help of ROS, ATA could release Ag+ in concentrations sufficient to inhibit periodontal pathogens as well. Moreover, the in situ-generated oxygen was supposed to alleviate the local hypoxic environment and would help downregulate the lipopolysaccharide-mediated inflammatory response of periodontal stem cells. The in vivo rat periodontitis treatment results demonstrated that the ATA/H2O2/NIR system reduced the bacterial load, relieved inflammation, and improved tissue healing. Our work developed a new local prolonged bactericidal and oxygenation system for enhanced periodontitis. Avoiding the usage of antibiotics and nanomaterials, this strategy showed great promise in adjunctive periodontitis treatment and also in other biomedical applications.
Titanium dioxide (TiO 2 ) is a widely used low-cost and stable photocatalyst, but its wide bandgap and low quantum efficiency usually lead to poor photocatalytic performance. Herein, one-step solid state calcination and reduction method was proposed for simultaneously introducing surface defects and loading Ag nanoparticles (NP) on TiO 2 . The as-obtained black TiO 2-x supported Ag NP (or Ag/TiO 2-x ) holds a narrow bandgap to respond to the full solar spectrum due to the presence of high concentration surface vacancies, enhanced light absorption through the surface plasmon resonance effect of Ag NP, and satisfactory photothermal effects. Moreover, such a one-step solid state synthesis method leads to closely linked interface and enhanced charges transfer between Ag NP and TiO 2-x . Accordingly, Ag/TiO 2-x exhibits robust photothermal synergistic VOCs degradation performance with a toluene degradation rate 6 times higher than the reference Ag/TiO 2 (DP) prepared by the conventional solution method.
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