Machine learning-guided realization of full-color high-quantum-yield carbon quantum dots.

Carbon quantum dots (CQDs) have versatile applications in luminescence, whereas identifying optimal synthesis conditions has been challenging due to numerous synthesis parameters and multiple desired outcomes, creating an enormous search space. In this study, we present a novel multi-objective optimization strategy utilizing a machine learning (ML) algorithm to intelligently guide the hydrothermal synthesis of CQDs. Our closed-loop approach learns from limited and sparse data, greatly reducing the research cycle and surpassing traditional trial-and-error methods. Moreover, it also reveals the intricate links between synthesis parameters and target properties and unifies the objective function to optimize multiple desired properties like full-color photoluminescence (PL) wavelength and high PL quantum yields (PLQY). With only 63 experiments, we achieve the synthesis of full-color fluorescent CQDs with high PLQY exceeding 60% across all colors. Our study represents a significant advancement in ML-guided CQDs synthesis, setting the stage for developing new materials with multiple desired properties.

Engineering Built-In Electric Field Microenvironment of CQDs/g-C3N4 Heterojunction for Efficient Photocatalytic CO2 Reduction.

Graphitic carbon nitride (CN), as a nonmetallic photocatalyst, has gained considerable attention for its cost-effectiveness and environmentally friendly nature in catalyzing solar-driven CO2 conversion into valuable products. However, the photocatalytic efficiency of CO2 reduction with CN remains low, accompanied by challenges in achieving desirable product selectivity. To address these limitations, a two-step hydrothermal-calcination tandem synthesis strategy is presented, introducing carbon quantum dots (CQDs) into CN and forming ultra-thin CQD/CN nanosheets. The integration of CQDs induces a distinct work function with CN, creating a robust interface electric field after the combination. This electric field facilitates the accumulation of photoelectrons in the CQDs region, providing an abundant source of reduced electrons for the photocatalytic process. Remarkably, the CQD/CN nanosheets exhibit an average CO yield of 120 µmol g-1, showcasing an outstanding CO selectivity of 92.8%. The discovery in the work not only presents an innovative pathway for the development of high-performance photocatalysts grounded in non-metallic CN materials employing CQDs but also opens new avenues for versatile application prospects in environmental protection and sustainable cleaning energy.

Spatially Confined Microcells: A Path toward TMD Catalyst Design.

With the ability to maximize the exposure of nearly all active sites to reactions, two-dimensional transition metal dichalcogenide (TMD) has become a fascinating new class of materials for electrocatalysis. Recently, electrochemical microcells have been developed, and their unique spatial-confined capability enables understanding of catalytic behaviors at a single material level, significantly promoting this field. This Review provides an overview of the recent progress in microcell-based TMD electrocatalyst studies. We first introduced the structural characteristics of TMD materials and discussed their site engineering strategies for electrocatalysis. Later, we comprehensively described two distinct types of microcells: the window-confined on-chip electrochemical microcell (OCEM) and the droplet-confined scanning electrochemical cell microscopy (SECCM). Their setups, working principles, and instrumentation were elucidated in detail, respectively. Furthermore, we summarized recent advances of OCEM and SECCM obtained in TMD catalysts, such as active site identification and imaging, site monitoring, modulation of charge injection and transport, and electrostatic field gating. Finally, we discussed the current challenges and provided personal perspectives on electrochemical microcell research.

Gram-Scale Mechanochemical Synthesis of Atom-Layer MoS2 Semiconductor Electrocatalyst via Functionalized Graphene Quantum Dots for Efficient Hydrogen Evolution.

The development of advanced and efficient synthetic methods is pivotal for the widespread application of 2D materials. In this study, a facile and scalable solvent-free mechanochemical approach is approached, employing graphene quantum dots (GQDs) as exfoliation agents, for the synthesis and functionalization of nearly atom-layered MoS2 nanosheets (ALMS). The resulting ALMS exhibits an ultrathin average thickness of 4 nm and demonstrates high solvent stability. The impressive yield of ALMS reached 63%, indicating its potential for scalable production of stable nanosheets. Remarkably, the ALMS catalyst exhibits excellent HER performance. Moreover, the ALMS catalyst showcases exceptional long-term durability, maintaining stable performance for nearly 200 h, underscoring its potential as a highly efficient and durable electrocatalyst. Significantly, the catalytic properties of ALMS are significantly influenced by ball milling production conditions. The GQD-assisted large-scale machinery synthesis pathway provides a promising avenue for the development of efficient and high-performance ultrathin 2D materials.

Bias-free driven ion assisted photoelectrochemical system for sustainable wastewater treatment.

Photoelectrochemical (PEC) systems have emerged as a prominent renewable energy-based technology for wastewater treatment, offering sustainable advantages such as eliminating dependence on fossil fuels or grid electricity compared to traditional electrochemical treatment methods. However, previous PEC systems often overlook the potential of ions present in wastewater as an alternative to externally applied bias voltage for enhancing carrier separation efficiency. Here we report a bias-free driven ion assisted photoelectrochemical (IAPEC) system by integration of an electron-ion acceptor cathode, which leverages its fast ion-electron coupling capability to significantly enhance the separation of electrons and holes at the photoanode. We demonstrate that Prussian blue analogues (PBAs) can serve as robust and reversible electron-ion acceptors that provide reaction sites for photoelectron coupling cations, thus driving the hole oxidation to produce strong oxidant free radicals at photoanode. Our IAPEC system exhibits superior degradation performance in wastewater containing chloride medium. This indicates that, in addition to the cations (e.g., Na+) accelerating the electron transfer rate, the presence of Cl- ions further enhance efficient and sustainable wastewater treatment. This work highlights the potential of utilizing abundant sodium chloride in seawater as a cost-effective additive for wastewater treatment, offering crucial insights into the use of local materials for effective, low-carbon, and sustainable treatment processes.

Graphene Quantum Dot-Mediated Atom-Layer Semiconductor Electrocatalyst for Hydrogen Evolution.

The hydrogen evolution reaction performance of semiconducting 2H-phase molybdenum disulfide (2H-MoS2) presents a significant hurdle in realizing its full potential applications. Here, we utilize theoretical calculations to predict possible functionalized graphene quantum dots (GQDs), which can enhance HER activity of bulk MoS2. Subsequently, we design a functionalized GQD-induced in-situ bottom-up strategy to fabricate near atom-layer 2H-MoS2 nanosheets mediated with GQDs (ALQD) by modulating the concentration of electron withdrawing/donating functional groups. Experimental results reveal that the introduction of a series of functionalized GQDs during the synthesis of ALQD plays a crucial role. Notably, the higher the concentration and strength of electron-withdrawing functional groups on GQDs, the thinner and more active the resulting ALQD are. Remarkably, the synthesized near atom-layer ALQD-SO3 demonstrate significantly improved HER performance. Our GQD-induced strategy provides a simple and efficient approach for expanding the catalytic application of MoS2. Furthermore, it holds substantial potential for developing nanosheets in other transition-metal dichalcogenide materials.

The inhibitory effect and mechanism of theaflavins on fluoride transport and uptake in HIEC-6 cell model.

Fluoride (F-) is widely present in nature, while long-term excessive F- intake can lead to fluorosis. Theaflavins are an important bioactive ingredient of black and dark tea, and black and dark tea water extracts showed a significantly lower F- bioavailability than NaF solutions in previous studies. In this study, the effect and mechanism of four theaflavins (theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate, theaflavin-3,3'-digallate) on F- bioavailability were investigated using normal human small intestinal epithelial cells (HIEC-6) as a model. The results showed that theaflavins could inhibit the absorptive (apical - basolateral) transport of F- while promote its secretory (basolateral - apical) transport in HIEC-6 cell monolayers in a time- and concentration-dependent (5-100 µg/mL) manner, and significantly reduce the cellular F- uptake. Moreover, the HIEC-6 cells treated with theaflavins showed a reduction in cell membrane fluidity and cell surface microvilli. Transcriptome, qRT-PCR and Western blot analysis revealed that theaflavin-3-gallate (TF3G) addition could significantly enhance the mRNA and protein expression levels of tight junction-related genes in HIEC-6 cells, such as claudin-1, occludin and zonula occludens-1 (ZO-1). Overall, theaflavins may reduce F- absorptive transport by regulating tight junction-related proteins, and decreasing intracellular F- accumulation by affecting the cell membrane structure and properties in HIEC-6 cells.

Solvent Engineering of Oxygen-Enriched Carbon Dots for Efficient Electrochemical Hydrogen Peroxide Production.

The development of cost-effective and reliable metal-free carbon-based electrocatalysts has gained significant attention for electrochemical hydrogen peroxide (H2 O2 ) generation through a two-electron oxygen reduction reaction. In this study, a scalable solvent engineering strategy is employed to fabricate oxygen-doped carbon dots (O-CDs) that exhibit excellent performance as electrocatalysts. By adjusting the ratio of ethanol and acetone solvents during the synthesis, the surface electronic structure of the resulting O-CDs can be systematically tuned. The amount of edge active CO group was strongly correlated with the selectivity and activity of the O-CDs. The optimum O-CDs-3 exhibited extraordinary H2 O2 selectivity of up to 96.55% (n = 2.06) at 0.65 V (vs RHE) and achieved a remarkably low Tafel plot of 64.8 mV dec-1 . Furthermore, the realistic H2 O2 productivity yield of flow cell is measured to be as high as 111.18 mg h-1  cm-2 for a duration of 10 h. The findings highlight the potential of universal solvent engineering approach for enabling the development of carbon-based electrocatalytic materials with improved performance. Further studies will be undertaken to explore the practical implications of the findings for advancing the field of carbon-based electrocatalysis.

Effect and Mechanism of Theaflavins on Fluoride Transport and Absorption in Caco-2 Cells.

This paper investigated the effect and mechanism of theaflavins (TFs) on fluoride (F-) uptake and transport in the Caco-2 cell model through structural chemistry and transcriptome analysis. The results showed that the four major TFs (TF, TF3G, TF3'G and TFDG) at a 150 µg/mL concentration could all significantly decrease F- transport in Caco-2 cells after 2 h of treatment and, at 2 µg/mL F- concentration, the F- transport was more inclined to efflux. During transport, the F- retention in Caco-2 cells was significantly increased by TF3G while it was clearly decreased by TF. The interaction between TFs and F- was analyzed by Raman spectroscopy and isothermal titration calorimetry, and F- was shown to affect the π bond vibration on the benzene ring of TFs, thus influencing their stability. Additionally, F- showed weak binding to TF3G, TF3'G and TFDG, which may inhibit F- transport and absorption in the Caco-2 cell line. Transcriptome and RT-PCR analysis identified three key differentially expressed genes related to cell permeability, and TFs can be assumed to mediate F- transport by regulating the expression of permeability-related genes to change cell monolayer permeability and enhance cell barrier function; however, this needs to be further elucidated in future studies.

Highly sensitive determination of cadmium and lead in whole blood by electrothermal vaporization-atmospheric pressure glow discharge atomic emission spectrometry.

In this study, a fast and simple method for highly sensitive detection of Cd and Pb elements based on atmospheric pressure glow discharge atomic emission spectrometry (APGD-AES) coupling with tungsten coil electrothermal vaporization (ETV) was proposed. A small amount of sample (10 µL) was dropped onto the tungsten coil, followed by drying, pyrolysis and vaporization procedures, and then the vaporized analyte was transported to APGD for excitation. The whole procedure took approximately 3 min. Multi-step heating of the ETV unit can separate matrices and solvents from the analyte, providing an advantage in detecting samples with complex matrix. Under the optimal experimental conditions, limits of detection of 0.4 µg L-1 (4 pg) for cadmium and 1.2 µg L-1 (12 pg) for lead were obtained, with relative standard deviations of 20 µg L-1 Cd and 100 µg L-1 Pb both being <5%. The accuracy of the ETV-APGD-AES system was verified by the determination of heavy metals in whole blood standard sample (GBW(E)090,251) and the practicability of the ETV-APGD-AES system were demonstrated by the determination of heavy metals in human whole blood. The results obtained by this instrument agree well with the standard values and those obtained by ICP-MS.

A Flexi-PEGDA Upconversion Implant for Wireless Brain Photodynamic Therapy.

Near-infrared (NIR) activatable upconversion nanoparticles (UCNPs) enable wireless-based phototherapies by converting deep-tissue-penetrating NIR to visible light. UCNPs are therefore ideal as wireless transducers for photodynamic therapy (PDT) of deep-sited tumors. However, the retention of unsequestered UCNPs in tissue with minimal options for removal limits their clinical translation. To address this shortcoming, biocompatible UCNPs implants are developed to deliver upconversion photonic properties in a flexible, optical guide design. To enhance its translatability, the UCNPs implant is constructed with an FDA-approved poly(ethylene glycol) diacrylate (PEGDA) core clad with fluorinated ethylene propylene (FEP). The emission spectrum of the UCNPs implant can be tuned to overlap with the absorption spectra of the clinically relevant photosensitizer, 5-aminolevulinic acid (5-ALA). The UCNPs implant can wirelessly transmit upconverted visible light till 8 cm in length and in a bendable manner even when implanted underneath the skin or scalp. With this system, it is demonstrated that NIR-based chronic PDT is achievable in an untethered and noninvasive manner in a mouse xenograft glioblastoma multiforme (GBM) model. It is postulated that such encapsulated UCNPs implants represent a translational shift for wireless deep-tissue phototherapy by enabling sequestration of UCNPs without compromising wireless deep-tissue light delivery.

An Excitation Navigating Energy Migration of Lanthanide Ions in Upconversion Nanoparticles.

Upconversion nanoparticles (UCNPs) doped with lanthanide ions that possess ladder-like energy levels can give out multiple emissions at specific ultra-violet or visible wavelengths irrespective of excitation light. However, precisely controlling energy migration processes between different energy levels of the same lanthanide ion to generate switchable emissions remains elusive. Herein, a novel dumbbell-shaped UCNP is reported with upconverted red emission switched to green emission when excitation wavelength changed from 980 to 808 nm. The sensitizer Yb ions are doped with activator Er ions and energy modulator Mn ions in NaYF4 core nanocrystal coated with an inner NaYF4 :Yb shell to generate red emission after harvesting 980 nm excitation light, while an outer NaNdF4 :Yb shell is coated to form a dumbbell shape to generate green emission upon 808 nm excitation. Such specially designed UCNPs with switchable green and red emissions are further explored for imaging of latent fingerprint and detection of explosive residues in the fingerprint simultaneously. This work suggests a novel research interest in fine-tuning of upconversion emissions through precisely controlling energy migration processes of the same lanthanide activator ion. Furthermore, use of these nanoparticles in other applications such as simultaneous dual-color imaging or orthogonal bidirectional photoactivation can be explored.

Nanoelectrode design from microminiaturized honeycomb monolith with ultrathin and stiff nanoscaffold for high-energy micro-supercapacitors.

Downsizing the cell size of honeycomb monoliths to nanoscale would offer high freedom of nanostructure design beyond their capability for broad applications in different fields. However, the microminiaturization of honeycomb monoliths remains a challenge. Here, we report the fabrication of microminiaturized honeycomb monoliths-honeycomb alumina nanoscaffold-and thus as a robust nanostructuring platform to assemble active materials for micro-supercapacitors. The representative honeycomb alumina nanoscaffold with hexagonal cell arrangement and 400 nm inter-cell spacing has an ultrathin but stiff nanoscaffold with only 16 ± 2 nm cell-wall-thickness, resulting in a cell density of 4.65 × 109 cells per square inch, a surface area enhancement factor of 240, and a relative density of 0.0784. These features allow nanoelectrodes based on honeycomb alumina nanoscaffold synergizing both effective ion migration and ample electroactive surface area within limited footprint. A micro-supercapacitor is finally constructed and exhibits record high performance, suggesting the feasibility of the current design for energy storage devices.

Effects of ivabradine hydrochloride combined with trimetazidine on myocardial fibrosis in rats with chronic heart failure.

Effects of ivabradine hydrochloride (Iva) and trimetazidine on myocardial fibrosis (MF) in rats with chronic heart failure (CHF) werφe explored. Fifty Wistar rats were randomly divided into sham operation, model, Iva, trimetazidine and combined drug group with 10 rats each. All rats except those in sham operation group were subjected to establish CHF model by constricting the abdominal aorta. After successful modeling, rats in the sham operation and model group received normal saline (10 mg/kg) gavage daily, the Iva group received Iva (10 mg/kg) gavage, the trimetazidine group received trimetazidine (10 mg/kg) gavage, and the combined drug group were given Iva (10 mg/kg) and trimetazidine (10 mg/kg) gavage for 12 weeks. The changes of hemodynamic indexes and heart rate, connective tissue growth factor (CTGF) and superoxide dismutase (SOD) levels as well as transforming growth factor ß1 (TGF-ß1) and collagen I (COL-I) expression levels in myocardial tissue of each group were detected. Compared with sham operation group, the left ventricular end-diastolic pressure (LVEDP) level, CTGF expression, TGF-ß1 mRNA and COL-I mRNA expression levels in model group increased significantly, but the ± dp/dtmax and SOD content in myocardial tissue decreased significantly. Compared with model group, the LVEDP level, CTGF expression, TGF-ß1 mRNA and COL-I mRNA expression levels in Iva group, trimetazidine group and combined drugs decreased significantly, but the ± dp/dtmax and the SOD content in myocardial tissue increased significantly (P<0.05). Changes in the combined drug group were the most notable (P<0.05). Iva combined with trimetazidine reduces LVEDP in rat with CHF, increases SOD content, and inhibits CTGF expression and TGF-ß1 and COL-I expression levels in myocardial tissues, thus achieving the inhibitory effect on MF.

Van der Waals negative capacitance transistors.

The Boltzmann distribution of electrons sets a fundamental barrier to lowering energy consumption in metal-oxide-semiconductor field-effect transistors (MOSFETs). Negative capacitance FET (NC-FET), as an emerging FET architecture, is promising to overcome this thermionic limit and build ultra-low-power consuming electronics. Here, we demonstrate steep-slope NC-FETs based on two-dimensional molybdenum disulfide and CuInP2S6 (CIPS) van der Waals (vdW) heterostructure. The vdW NC-FET provides an average subthreshold swing (SS) less than the Boltzmann's limit for over seven decades of drain current, with a minimum SS of 28 mV dec-1. Negligible hysteresis is achieved in NC-FETs with the thickness of CIPS less than 20 nm. A voltage gain of 24 is measured for vdW NC-FET logic inverter. Flexible vdW NC-FET is further demonstrated with sub-60 mV dec-1 switching characteristics under the bending radius down to 3.8 mm. These results demonstrate the great potential of vdW NC-FET for ultra-low-power and flexible applications.

Photodynamic therapy as salvage therapy for residual microscopic cancer after ultra-low anterior resection: A case report.

BACKGROUND: The rate of positive resection margins (R1) in patients with low rectal cancer is substantial. Recommended remedies such as extended resection or chemoradiotherapy have their own serious drawbacks. It has been reported that photodynamic therapy (PDT) as a remedial treatment for esophageal cancer. Colorectal cancer and esophageal cancer has many similarities, however, PDT as a salvage therapy for rectal cancer is rare. CASE SUMMARY: Here, we describe a 56-year-old man who was admitted to the hospital due to a 6-mo history of hemafecia, which had been aggravated for 1 mo. Colonoscopy revealed a 3 cm × 4 cm ulcerated mass in the rectum 4 cm from the anus. Preoperative pathological examination showed villous adenoma, moderate-to-high-grade dysplasia, good differentiation, and invasion of the mucosal muscle. The patient had R1 after ultra-low anterior resection, but he refused extended resection and experienced severe liver function impairment after 3 cycles of chemotherapy. Ultimately, the patient underwent PDT to remove R1. After five years of follow-up, there was no liver function impairment, recurrence, metastasis, sexual dysfunction, or abnormal defecation function. CONCLUSION: This is the first case worldwide in which R1 of rectal cancer were successfully treated by PDT.

A Highly Efficient Tumor-Targeting Nanoprobe with a Novel Cell Membrane Permeability Mechanism.

Efficient tumor targeting has been a great challenge in the clinic for a very long time. The traditional targeting methods based on enhanced permeability and retention (EPR) effects show only an ≈5% targeting rate. To solve this problem, a new graphene-based tumor cell nuclear targeting fluorescent nanoprobe (GTTN), with a new tumor-targeting mechanism, is developed. GTTN is a graphene-like single-crystalline structure amphiphilic fluorescent probe with a periphery that is functionalized by sulfonic and hydroxyl groups. This probe has the characteristic of specific tumor cell targeting, as it can directly cross the cell membrane and specifically target to the tumor cell nucleus by the changed permeability of the tumor cell membranes in the tumor tissue. This new targeting mechanism is named the cell membrane permeability targeting (CMPT) mechanism, which is very different from the EPR effect. These probes can recognize tumor tissue at a very early stage and track the invasion and metastasis of tumor cells at the single cell level. The tumor-targeting rate is improved from less than 5% to more than 50%. This achievement in efficient and accurate tumor cell targeting will speed up the arrival of a new era of tumor diagnosis and treatment.

The Influence of Carbon Nitride Nanosheets Doping on the Crystalline Formation of MIL-88B(Fe) and the Photocatalytic Activities.

In this research, bulk graphitic carbon nitride (g-C3 N4 ) is exfoliated and transferred to the carbon nitride nanosheets (CNNSs), which are then coupled with MIL-88B(Fe) to form the hybrid. From the results of the powder X-ray diffraction, scanning electronic microscopy and thermogravimetric analysis, it is found that the doping of CNNSs on the surface of MIL-88(Fe) could maintain the basic structure of MIL-88B(Fe), and the smaller dimension of CNNSs might influence the crystallization process of metal-organic frameworks (MOFs) compared to bulk g-C3 N4 . Besides, the effects of the CNNSs incorporation on photocatalysis are also investigated. Through the photoluminescence spectra, electrochemical measurements, and photocatalytic experiments, the hybrid containing 6% CNNSs is certified to possess the highest catalytic activity to degrade methylene blue and reduce Cr(VI) under visible light. The improvement of the photocatalytic performance can be attributed to the matched energy level which favors the formation of the heterojunctions. Besides, it promotes the charge migration such that the contact between MOFs and CNNSs is more intimate, which can be inferred from the electronic microscopy images. Finally, a possible photocatalytic mechanism is put forward by the relative calculation and the employment of the scavengers to trap the active species.

Strong Coupling of MoS2 Nanosheets and Nitrogen-Doped Graphene for High-Performance Pseudocapacitance Lithium Storage.

Layered material MoS2 is widely applied as a promising anode for lithium-ion batteries (LIBs). Herein, a scalable and facile dopamine-assisted hydrothermal technique for the preparation of strongly coupled MoS2 nanosheets and nitrogen-doped graphene (MoS2 /N-G) composite is developed. In this composite, the interconnected MoS2 nanosheets are well wrapped onto the surface of graphene, forming a unique veil-like architecture. Experimental results indicate that dopamine plays multiple roles in the synthesis: a binding agent to anchor and uniformly disperse MoS2 nanosheets, a morphology promoter, and the precursor for in situ nitrogen doping during the self-polymerization process. Density functional theory calculations further reveal that a strong interaction exists at the interface of MoS2 nanosheets and nitrogen-doped graphene, which facilitates the charge transfer in the hybrid system. When used as the anode for LIBs, the resulting MoS2 /N-G composite electrode exhibits much higher and more stable Li-ion storage capacity (e.g., 1102 mAh g-1 at 100 mA g-1 ) than that of MoS2 /G electrode without employing the dopamine linker. Significantly, it is also identified that the thin MoS2 nanosheets display outstanding high-rate capability due to surface-dominated pseudocapacitance contribution.

Boosting lithium storage in covalent organic framework via activation of 14-electron redox chemistry.

Conjugated polymeric molecules have been heralded as promising electrode materials for the next-generation energy-storage technologies owing to their chemical flexibility at the molecular level, environmental benefit, and cost advantage. However, before any practical implementation takes place, the low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles that have to be overcome. Here, we report the synthesis of a few-layered two-dimensional covalent organic framework trapped by carbon nanotubes as the anode of lithium-ion batteries. Remarkably, upon activation, this organic electrode delivers a large reversible capacity of 1536 mAh g-1 and can sustain 500 cycles at 100 mA g-1. Aided by theoretical calculations and electrochemical probing of the electrochemical behavior at different stages of cycling, the storage mechanism is revealed to be governed by 14-electron redox chemistry for a covalent organic framework monomer with one lithium ion per C=N group and six lithium ions per benzene ring. This work may pave the way to the development of high-capacity electrodes for organic rechargeable batteries.