TiO2 nanotube arrays with visible light catalytic.

The TiO2 nanotube arrays were prepared by anodization, and the crystal structure was changed by calcination at different temperatures. The photocatalytic performance of the samples was measured by the degradation of rhodamine B under visible light. The TiO2 nanotubes calcined at 600 °C showed higher photocatalytic activity than other samples. The prepared catalyst is characterized by a variety of techniques, including X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Raman, photoluminescence spectroscopy and electrochemical testing. The reasons for improving the catalytic activity were studied from the aspects of crystal structure, surface morphology, and photoelectric properties, and the catalytic mechanism was studied. The results show that the TiO2 nanotubes calcined at 600°C contain two phases of anatase and rutile. Compared with pure phase TiO2, the charge transfer resistance is reduced and the electron-hole reorganization is well suppressed. In addition, it affects the band structure and improves the absorption of visible light. At the same time, studies have found that the main active substances in the catalytic process are h+ and •OH.

Amplifying Upconversion by Engineering Interfacial Density of State in Sub-10 nm Colloidal Core/Shell Fluoride Nanoparticles.

Achieving bright photon upconversion under low irradiance is of great significance and finds many stimulating applications from photovoltaics to biophotonics. However, it remains a daunting challenge to significantly intensify upconversion luminescence in small nanoparticles with a simple structure. Herein, we report the amplification of photon upconversion through engineering interfacial density of states between the core and the shell layer in sub-10 nm colloidal rare-earth ions doped fluoride nanocrystals. Through tuning of the metal cations in the shell layer of alkaline-earth-based core/shell nanoparticles, both the interfacial phonon frequency and the density of state are evidently decreased, resulting in the luminescence intensification of up to 8224 times. The generality of this upconversion enhancement strategy has been verified through expansion of this approach to alkali-based core/shell nanoparticles. The engineering of photon density of state in such core/shell nanoparticles enables dynamic display and high-level security information storage.

Overlooked role of aqueous chromate (VI) as a photosensitizer in enhancing the photochemical reactivity of ferrihydrite and production of hydroxyl radical.

The reactive oxygen species (ROS) photochemically generated from natural iron minerals have gained significant attention. Amidst the previous studies on the impact of heavy metal ions on ROS generation, our study addresses the role of the anion Cr(VI), with its intrinsic photoactivity, in influencing ROS photochemical generation with the co-presence of minerals. We investigated the transformation of inorganic/organic pollutants (Cr(VI) and benzoic acid) at the ferrihydrite interface, considering sunlight-mediated conversion processes (300-1000 nm). Increased photochemical reactivity of ferrihydrite was observed in the presence of aqueous Cr(VI), acting as a photosensitizer. Meanwhile, a positive correlation between hydroxyl radical (•OH) production and concentrations of aqueous Cr(VI) was observed, with a 650% increase of •OH generation at 50 mg L-1 Cr(VI) compared to systems without Cr(VI). Our photochemical batch experiments elucidated three potential pathways for •OH photochemical production under varying wet chemistry conditions: (1) ferrihydrite hole-mediated pathway, (2) chromium intermediate O-I-mediated pathway, and (3) chromium intermediates CrIV/V-mediated pathway. Notably, even in the visible region (> 425 nm), the promotion of aqueous Cr(VI) on •OH accumulation was observed in the presence of ferrihydrite and TiO2 suspensions, attributed to Cr(VI) photosensitization at the mineral interface. This study sheds light on the overlooked role of aqueous Cr(VI) in the photochemical reactivity of minerals, thereby enhancing our understanding of pollutant fate in acid mining-impacted environments.

Improved relative temperature sensitivity of over 10% K-1 in fluoride nanocrystals via engineering the interfacial layer.

Real-time in situ temperature sensing is of significance in the bio-medical field; however, the low relative temperature sensitivity Sr is one of the major obstacles in the development of nanothermometers. Herein, we provide an effective route that engineers the interfacial layer in a core/shell/shell nanostructure to enlarge the temperature-dependent luminescence intensity ratio (LIR) variations followed by an improved Sr. The CaF2 interlayer is employed to inhibit the interaction between the core and outer shell, and increase the interfacial phonon energy to enhance the negative thermal quenching effect (TQE) of Nd3+ ions in the outer shell and positive TQE of Er3+ ions in the core layer. Based on the temperature-dependent LIR variations of Er (650 nm) to Nd (800 nm), the maximum Sr of 10.01% K-1 and minimum Sr of % 2.56% K-1 are achieved.

Advances on biodegradable zinc-silver-based alloys for biomedical applications.

The biodegradable metals have great potential for the biomedical applications, which could be gradually degraded, absorbed, or excreted in the human body, avoiding the removal though secondary surgery. Zinc-based alloys are novel series of degradable metals for medical applications, and they are gaining lots of attention in the research field of absorbable metals. Zinc-silver (Zn-Ag) alloys show superior mechanical strength, good biodegradability, biocompatibility, and antibacterial properties, which render them to be potential candidates for biomedical applications. In this paper, we reviewed the development of Zn-Ag alloys in terms of mechanical properties, degradabilities, biocompatibilities, antibacterial properties, and potential applications in dentistry.

Constructing highly sensitive ratiometric nanothermometers based on indirectly thermally coupled levels.

Fluorescence intensity ratio-based temperature sensing with a self-referencing characteristic is highly demanded for reliable and accurate sensing. Lanthanide ions with thermally coupled levels have been widely used for ratiometric temperature sensing. However, these systems suffer from low relative temperature sensitivity and poor luminescence signal discriminability. Herein, the concept of indirectly thermally coupled levels is introduced and employed to actualize high performance temperature sensing. By means of the temperature-dependent phonon-assisted non-radiative relaxation, the 4I13/2 excited state (with infrared emission) of Er3+ can be indirectly thermally coupled with the 4S3/2 excited state (with visible emission) under 808 nm or 980 nm excitation. This is experimentally realized in specially designed NaErF4:10Yb@NaYF4 nanocrystals, and the corresponding ratiometric nanothermometer shows excellent luminescence thermal sensing performance with a maximum relative sensitivity value up to 3.76% K-1 at 295 K.

Modulating electron population pathways for time-dependent dynamic multicolor displays.

Multicolor luminescent nanoparticles (NPs) show several potential emerging applications. In this work, we provide a new route that integrates the afterglow and upconversion (UC) that originate in a single activator to achieve color variations without the modulation of any other parameters. The Er3+ ions in Na3HfF7:Yb/Er NPs exhibit bright green afterglow upon X-ray irradiation and single-band red UC under 980 nm laser excitation, which are attributed to the significantly different electron population pathways. The UC intensity is stable and the afterglow decreases gradually over time, thus the output color is clearly changed from green to red naturally via illuminating the pre-X-ray-irradiated NPs with a 980 nm laser. Furthermore, the fine emission profiles of Er3+, Ho3+ and Tm3+ are achieved upon X-ray irradiation. Our results develop a new approach for time-dependent dynamic color displays and a simple route to revealing the electronic fine structures of lanthanide activators at room temperature.

Cancer-derived sialylated IgG promotes tumor immune escape by binding to Siglecs on effector T cells.

To date, IgG in the tumor microenvironment (TME) has been considered a product of B cells and serves as an antitumor antibody. However, in this study, using a monoclonal antibody against cancer-derived IgG (Cancer-IgG), we found that cancer cells could secrete IgG into the TME. Furthermore, Cancer-IgG, which carries an abnormal sialic acid modification in the CH1 domain, directly inhibited effector T-cell proliferation and significantly promoted tumor growth by reducing CD4+ and CD8+ T-cell infiltration into tumor tissues. Mechanistic studies showed that the immunosuppressive effect of sialylated Cancer-IgG is dependent on its sialylation and binding to sialic acid-binding immunoglobulin-type lectins (Siglecs) on effector CD4+ and CD8+ T cells. Importantly, we show that several Siglecs are overexpressed on effector T cells from cancer patients, but not those from healthy donors. These findings suggest that sialylated Cancer-IgG may be a ligand for Siglecs, which may serve as potential checkpoint proteins and mediate tumor immune evasion.

Nano-zirconia supported by graphitic carbon nitride for enhanced visible light photocatalytic activity.

Graphitic carbon nitride (g-C3N4) was prepared by high-temperature calcination of urea. A mixture of g-C3N4 and nano-ZrO2 precursor was directly calcined to prepare g-C3N4/ZrO2 hybrid photocatalysts. The photocatalytic properties of the sample were characterized by degradation of rhodamine B (RhB) under visible light. The g-C3N4/ZrO2 hybrid photocatalysts have better degradation performance than the pure g-C3N4 and ZrO2. The prepared catalysts were characterized by various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence spectroscopy (PL) and electrochemical tests. The reasons for the improvement of catalytic activity were investigated from the aspects of crystal structure, surface morphology and photoelectric properties, and the catalytic mechanism were studied. The results show that the ZrO2 nanoparticles were coated with g-C3N4 to form a heterostructure. Compared with the pure g-C3N4 and ZrO2, the g-C3N4/ZrO2 hybrids reduce the charge transfer resistance and inhibit the recombination of electron-holes well. In addition, it affects the band structure and improves the absorption of visible-light. At the same time, the study found that the main active species in the catalytic process were h+ and ·O2 -.

Epithelial cells are a source of natural IgM that contribute to innate immune responses.

Currently, natural IgM antibodies are considered to be the constitutively secreted products of B-1 cells in mice and humans. In this study, we found that mouse epithelial cells, including liver epithelial cells and small intestinal epithelial cells (IECs), could express IgM that also showed natural antibody activity. Moreover, similar to the B-1 cell-derived natural IgM that can be upregulated by TLR9 agonists (mimicking bacterial infection), the expression of epithelial cell-derived natural IgM could also be significantly increased by TLR9 signaling. More importantly, the epithelial cell-derived IgM was polyreactive, and it could recognize single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), lipopolysaccharide (LPS), and insulin with low affinity; additionally, TLR9 agonists could enhance it in a MyD88-dependent manner. Furthermore, epithelial cell-derived IgM could bind various bacteria; therefore, it could be involved in anti-infection responses. Together, these results highlight the fact that epithelial cells are an important source of natural IgM, in addition to that produced by B-1 cells, and IgM contributes to the innate immune responses in local tissues, further demonstrating that the epithelium is a first line of defense in the protection against invading microbes.

Identification of Liver Epithelial Cell-derived Ig Expression in µ chain-deficient mice.

Growing evidence indicates that B cells are not the only source of immunoglobulin (Ig). To investigate this discovery further, we used µMT mice, which have a disruption of the first transmembrane exon of the µ heavy chain and do not express the membrane form of IgM. These mice lack mature B cells and thus serve as a good model to explore Ig expression by liver epithelial cells. We found that Ig heavy chains (µ, δ, γ and α) and light chains (κ and λ) were expressed in sorted liver epithelial cells of µMT mice. Surprisingly, each heavy chain class showed its respective variable region sequence characteristics in their variable region, instead of sharing the same VDJ usage, which suggests that class switching does not occur in liver epithelial cells. Moreover, the γ and α chains, but not the µ and δ chains, showed mutations in the variable region, thus indicating that different classes of Ig have different activities. Our findings support the concept that non-B cells, liver epithelial cells here, can produce different classes of Ig.