Abstract
Oxygen reduction reaction towards hydrogen peroxide (H
2
O
2
) provides a green alternative route for H
2
O
2
production, but it lacks efficient catalysts to achieve high selectivity and ...activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm
−2
) while maintaining high H
2
O
2
selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H
2
O
2
activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H
2
O
2
solutions with high selectivity (up to 95%) and high H
2
O
2
partial currents (up to ~400 mA cm
−2
), illustrating the catalyst’s great potential for practical applications in the future.
Nanoscale carbides enhance ultra-strong ceramics and show activity as high-performance catalysts. Traditional lengthy carburization methods for carbide syntheses usually result in coked surface, ...large particle size, and uncontrolled phase. Here, a flash Joule heating process is developed for ultrafast synthesis of carbide nanocrystals within 1 s. Various interstitial transition metal carbides (TiC, ZrC, HfC, VC, NbC, TaC, Cr
C
, MoC, and W
C) and covalent carbides (B
C and SiC) are produced using low-cost precursors. By controlling pulse voltages, phase-pure molybdenum carbides including β-Mo
C and metastable α-MoC
and η-MoC
are selectively synthesized, demonstrating the excellent phase engineering ability of the flash Joule heating by broadly tunable energy input that can exceed 3000 K coupled with kinetically controlled ultrafast cooling (>10
K s
). Theoretical calculation reveals carbon vacancies as the driving factor for topotactic transition of carbide phases. The phase-dependent hydrogen evolution capability of molybdenum carbides is investigated with β-Mo
C showing the best performance.
Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is a light-activated local treatment modality that is under intensive preclinical and clinical investigations for ...cancer. To enhance the treatment efficiency of phototherapy and reduce the light-associated side effects, it is highly desirable to improve drug accumulation and precision guided phototherapy for efficient conversion of the absorbed light energy to reactive oxygen species (ROS) and local hyperthermia. In the present study, a programmed assembly strategy was developed for the preparation of human serum albumin (HSA)-indocyanine green (ICG) nanoparticles (HSA-ICG NPs) by intermolecular disulfide conjugations. This study indicated that HSA-ICG NPs had a high accumulation with tumor-to-normal tissue ratio of 36.12 ± 5.12 at 24 h and a long-term retention with more than 7 days in 4T1 tumor-bearing mice, where the tumor and its margin, normal tissue were clearly identified via ICG-based in vivo near-infrared (NIR) fluorescence and photoacoustic dual-modal imaging and spectrum-resolved technology. Meanwhile, HSA-ICG NPs efficiently induced ROS and local hyperthermia simultaneously for synergetic PDT/PTT treatments under a single NIR laser irradiation. After an intravenous injection of HSA-ICG NPs followed by imaging-guided precision phototherapy (808 nm, 0.8 W/cm2 for 5 min), the tumor was completely suppressed, no tumor recurrence and treatments-induced toxicity were observed. The results suggest that HSA-ICG NPs generated by programmed assembly as smart theranostic nanoplatforms are highly potential for imaging-guided cancer phototherapy with PDT/PTT synergistic effects.
Fabricating inorganic materials with designed three-dimensional nanostructures is an exciting yet challenging area of research and industrial application. Here, we develop an approach to 3D print ...high-quality nanostructures of silica with sub-200 nm resolution and with the flexible capability of rare-earth element doping. The printed SiO
can be either amorphous glass or polycrystalline cristobalite controlled by the sintering process. The 3D-printed nanostructures demonstrate attractive optical properties. For instance, the fabricated micro-toroid optical resonators can reach quality factors (Q) of over 10
. Moreover, and importantly for optical applications, doping and codoping of rare-earth salts such as Er
, Tm
, Yb
, Eu
and Nd
can be directly implemented in the printed SiO
structures, showing strong photoluminescence at the desired wavelengths. This technique shows the potential for building integrated microphotonics with silica via 3D printing.
Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating optical and electronic properties. These have been synthesized either by nanolithography or from ...starting materials such as graphene oxide (GO) by the chemical breakdown of their extended planar structure, both of which are multistep tedious processes. Here, we report that during the acid treatment and chemical exfoliation of traditional pitch-based carbon fibers, that are both cheap and commercially available, the stacked graphitic submicrometer domains of the fibers are easily broken down, leading to the creation of GQDs with different size distribution in scalable amounts. The as-produced GQDs, in the size range of 1–4 nm, show two-dimensional morphology, most of which present zigzag edge structure, and are 1–3 atomic layers thick. The photoluminescence of the GQDs can be tailored through varying the size of the GQDs by changing process parameters. Due to the luminescence stability, nanosecond lifetime, biocompatibility, low toxicity, and high water solubility, these GQDs are demonstrated to be excellent probes for high contrast bioimaging and biosensing applications.
Abstract Photodynamic therapy (PDT) is a noninvasive and effective approach for cancer treatment. The main bottlenecks of clinical PDT are poor selectivity of photosensitizer and inadequate oxygen ...supply resulting in serious side effects and low therapeutic efficiency. Herein, a thermal-modulated reactive oxygen species (ROS) strategy using activatable human serum albumin-chlorin e6 nanoassemblies (HSA-Ce6 NAs) for promoting PDT against cancer is developed. Through intermolecular disulfide bond crosslinking and hydrophobic interaction, Ce6 photosensitizer is effectively loaded into the HSA NAs, and the obtained HSA-Ce6 NAs exhibit excellent reduction response, as well as enhanced tumor accumulation and retention. By the precision control of the overall body temperature instead of local tumor temperature increasing from 37 °C to 43 °C, the photosensitization reaction rate of HSA-Ce6 NAs increases 20%, and the oxygen saturation of tumor tissue raise 52%, significantly enhancing the generation of ROS for promoting PDT. Meanwhile, the intrinsic fluorescence and photoacoustic properties, and the chelating characteristic of porphyrin ring can endow the HSA-Ce6 NAs with fluorescence, photoacoustic and magnetic resonance triple-modal imaging functions. Upon irradiation of low-energy near-infrared laser, the tumors are completely suppressed without tumor recurrence and therapy-induced side effects. The robust thermal-modulated ROS strategy combined with albumin-based activatable nanophotosensitizer is highly potential for multi-modal imaging-guided PDT and clinical translation.
Multi-modal imaging-guided cancer photothermal therapy (PTT) with advanced theranostic nanoagents can efficiently improve therapeutic efficacy and reduce treatment side effects. Herein, we have ...developed a theranostic nanoagent based on indocyanine green (ICG)-loaded polydopamine (PDA)-iron ions coordination nanoparticles (PDA-Fe
-ICG NPs), which are used for photoacoustic (PA) and magnetic resonance (MR) dual-modal imaging-guided cancer PTT treatments. In this nanoplatform, ICG molecules, the U.S. Food and Drug Administration approved near-infrared (NIR) dye, absorbing on PDA NPs (a melanin-like biopolymer) to significantly increase the NIR optical absorption of PDA NPs nearly 6 times and decreases their fluorescence emission, which can improve the PA contrast ability and promote the photothermal conversion efficiency of PDA NPs. Meanwhile, Fe
ions chelated on the PDA NPs act as a T
-weighted MRI contrast agent (r
= 14 mM
s
). In a mouse 4T1 breast tumor model, PA/MRI dual-modal imaging and highly efficient PTT treatments with low laser density were achieved with remarkable therapeutic efficiency and minimal side effects. This study illustrates that the highly integrated and biocompatible PDA-based NPs can serve as a versatile nanoplatform by loading different imaging molecules and drugs for multi-modal imaging and cancer combination therapy.
Abstract A key challenge to strengthen anti-tumor efficacy is to improve drug accumulation in tumors through size control. To explore the biodistribution and tumor accumulation of nanoparticles, we ...developed indocyanine green (ICG) loaded poly (lactic-co-glycolic acid) (PLGA) -lecithin-polyethylene glycol (PEG) core-shell nanoparticles (INPs) with 39 nm, 68 nm and 116 nm via single-step nanoprecipitation. These INPs exhibited good monodispersity, excellent fluorescence and size stability, and enhanced temperature response after laser irradiation. Through cell uptake and photothermal efficiency in vitro , we demonstrated that 39 nm INPs were more easily be absorbed by pancreatic carcinoma tumor cells (BxPC-3) and showed better photothermal damage than that of 68 nm and 116 nm size of INPs. Simultaneously, the fluorescence of INPs offered a real-time imaging monitor for subcellular locating and in vivo metabolic distribution. Near-infrared imaging in vivo and photothermal therapy illustrated that 68 nm INPs showed the strongest efficiency to suppress tumor growth due to abundant accumulation in BxPC-3 xenograft tumor model. The findings revealed that a nontoxic, size-dependent, theranostic INPs model was built for in vivo cancer imaging and photothermal therapy without adverse effect.
Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms and defects have been ...intensively explored as active sites for the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a key type of defects in TMDs, have been overlooked due to their low density and large structural variations. Here, we demonstrate the synthesis of wafer-size atom-thin TMD films with an ultra-high-density of GBs, up to ~10
cm
. We propose a climb and drive 0D/2D interaction to explain the underlying growth mechanism. The electrocatalytic activity of the nanograin film is comprehensively examined by micro-electrochemical measurements, showing an excellent hydrogen-evolution performance (onset potential: -25 mV and Tafel slope: 54 mV dec
), thus indicating an intrinsically high activation of the TMD GBs.
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