Near-Infrared Light-Excited Reactive Oxygen Species Generation by Thulium Oxide Nanoparticles

Exploring materials that can absorb near-infrared (NIR) light to produce reactive oxygen species (ROS) is necessary for many fields. Herein we show that thulium oxide nanoparticles are viable for NIR-stimulated ROS generation. This property may be related to the unique energy levels, large absorption cross section, low fluorescence emission, and ∼10-3 s lifetime of the 3H4 state of Tm ions. We further demonstrate the impact of these nanoparticles on photodynamic therapy (PDT), in which impressive tumor inhibition was recorded after exposure to either a broadband halogen lamp or an 808 nm laser. Our results may provide insight into the areas of photocatalysis, pollution treatment, and fine chemical synthesis.

The Synergy between Antibiotics and the Nanoparticle-Based Photodynamic Effect

Antimicrobial resistance (AMR) is a growing global health concern, necessitating innovative strategies beyond the development of new antibiotics. Here, we employed NdYVO4:Eu3+ nanoparticles, which can persistently produce reactive oxygen species (ROS) after stopping the light, as a model of photodynamic nanoparticles and demonstrated that the photodynamic effect can serve as an adjuvant with antibiotics to effectively reduce their minimum inhibitory concentration. These preirradiated nanoparticles could penetrate the bacterial cell membrane, significantly enhancing the potency of antibiotics. We showed that the synergy effect could be attributed to disrupting crucial cellular processes by ROS, including damaging cell membrane proteins, interfering with energy supply, and inhibiting antibiotic metabolism. Our findings suggested that complementing the photodynamic effect might be a robust strategy to enhance antibiotic potency, providing an alternative antibacterial treatment paradigm.

Infiltrating Perfluorocarbon Nanoemulsion and Sensitizing Ultrasound Cavitation to Eradicate Biofilms

Developing strategies for the treatment of bacterial biofilms is challenging due to their complex and resilient structure, low permeability to therapeutics, and ability to protect resident pathogens. Herein, we demonstrate that a polylysine-stabilized perfluorocarbon nanoemulsion is favored for penetrating biofilms and sensitizing the cavitation effect of low-intensity ultrasound, resulting in the dispersal of extracellular polymeric substances and killing of the protected cells. Through experiments, we observed a complete penetration of the nanoemulsion in a 40 μm Pseudomonas aeruginosa biofilm and demonstrated that it was induced by the fluidic perfluorocarbon, possibly attributing to its low surface tension. Furthermore, we presented an almost complete antibiofilm effect with a low-intensity ultrasound (1 MHz, 0.75 W/cm2, 5 min) in diverse cases, including cultured biofilms, colonized urinary catheters, and chronic wounds. During the treatment process, the perfluorocarbon phase enhanced the number and imploding energy of ultrasound cavities, thoroughly divided the biofilm structure, prevented biofilm self-healing, and sterilized the resident pathogens. Thus, the penetration and sensitization of the nanoemulsion might serve as a facile and potent strategy for eradicating biofilms in various applications.

An Indocyanine Green-Based Nanocluster for Imaging Orthodox Endometriosis Lesions with Negative Contrast

Indocyanine green (ICG), as the sole near-infrared dye FDA-approved, is limited in biomedical applications because of its poor photostability, lack of targeting, and rapid removal in vivo. Herein, we presented a nanoformulation of poly-l-lysine-indocyanine green-hyaluronic acid (PIH) and demonstrated that it can image orthodox endometriosis (EM) lesions with a negative contrast. The PIH nanocluster, with an average diameter of approximately 200 nm, exhibited improved fluorescence photostability and antioxidant ability compared to free ICG. In the in vivo imaging, EM lesions were visualized, featuring apparent voids and clear boundaries. After colocalizing with the green fluorescent protein, we concluded that the contrast provided by PIH peaked at 4 h postinjection and was observable for at least 8 h. The negative contrast, clear boundaries, and enhanced observable time might be due to the low permeation of PIH to lesions and the enhanced retention on the surfaces of lesions. Thus, our findings suggest an ICG-based nanoprobe with the potential to diagnose abdominal diseases.

Erbium oxide nanoplates as a sonosensitizer devoid of photosensitivity

Phototoxicity is an undesirable consequence of photodynamic and most sonodynamic therapies. In the current work, we showed that Er₂O₃ nanoplates can avoid being cytotoxic when exposed to light and could be an effective sonosensitizer.

Ultrasmall Day-Night Photocatalysts of LnYVO4:Eu3+ (Ln = Nd, Tm, and Er) Nanoparticles

Day-night photocatalysts that can persistently generate reactive oxygen species (ROS) after ceasing light attracted intensive attention in diverse fields. However, current strategies of combining a photocatalyst and an energy storage material can hardly fulfill the demands, especially in size. We herein present a one-phase sub-5 nm day-night photocatalyst via simply doping Nd, Tm, or Er into YVO₄:Eu³⁺ nanoparticles, efficiently producing ROS in both day and night modes. We demonstrate that the rare earth ions acted as a ROS generator, and Eu³⁺ and defects contributed to the long persistency. Furthermore, the ultrasmall size led to remarkable bacterial uptake and bactericidal efficacy. Our finding suggests an alternative mechanism of day-night photocatalysts that could be ultrasmall and thus may shed light on disinfection and other applications.

Ba2+-doping introduced piezoelectricity and efficient Ultrasound-Triggered bactericidal activity of brookite TiO2 nanorods

Exploring highly efficient ultrasound-triggered catalysts is pivotal for various areas. Herein, we presented that Ba2+ doped brookite TiO2 nanorod (TiO2: Ba) with polarization-induced charge separation is a candidate. The replacement of Ba2+ for Ti4+ not only induced significant lattice distortion to induce polarization but also created oxygen vacancy defects for facilitating the charge separation, leading to high-efficiency reactive oxygen species (ROS) evolution in the piezo-catalytic processes. Furthermore, the piezocatalytic ability to degrade dye wastewater demonstrates a rate constant of 0.172 min-1 and achieves a 100 % antibacterial rate at a low dose for eliminating E. coli. This study advances that doping can induce piezoelectricity and reveals that lattice distortion-induced polarization and vacancy defects engineering can improve ROS production, which might impact applications such as water disinfection and sonodynamic therapy.