Boosting the photoelectrochemical performance of BiVO4 by borate buffer activation: the role of trace iron impurities.

BiVO4 is an attractive photoanode material for water oxidation, but requires surface treatment to improve the energy efficiency and stability. Herein, we investigate the role of borate buffer in activating the BiVO4 photoanode. We found that trace iron impurities in the borate buffer play a critical role in activating the photoanode. By optimizing the activation conditions, the photocurrent density attains 4.5 mA cm-2 at 1.23 VRHE without any cocatalysts, alongside a high ABPE value of 1.5% at 0.7 VRHE. Our study discloses the role of iron in the activation effect of borate buffer on the BiVO4 photoanode, which has implications for other catalytic systems.

A Near-Infrared-II Excitable Pyridinium Probe with 1000-Fold ON/OFF Ratio for γ-Glutamyltranspeptidase and Cancer Detection.

Activity-based detection of γ-Glutamyltranspeptidase (GGT) using near-infrared (NIR) fluorescent probes is a promising strategy for early cancer diagnosis. Although NIR pyridinium probes show high performance in biochemical analysis, the aggregation of both the probes and parental fluorochromes in biological environments is prone to result in a low signal-to-noise ratio (SBR), thus affecting their clinical applications. Here, we develop a GGT-activatable aggregate probe called OTBP-G for two-photon fluorescence imaging in various biological environments under 1040 nm excitation. By rationally tunning the hydrophilicity and donor-acceptor strength, we enable a synergistic effect between twisted intramolecular charge transfer and intersystem crossing processes and realize a perfect dark state for OTBP-G before activation. After the enzymatic reaction, the parental fluorochrome exhibits bright aggregation-induced emission peaking at 670 nm. The fluorochrome-to-probe transformation can induce 1000-fold fluorescence ON/OFF ratio, realizing in vitro GGT detection with an SBR > 900. Activation of OTBP-G occurs within 1 min in vivo, showing an SBR > 400 in mouse ear blood vessels. OTBP-G can further enable the early detection of pulmonary metastasis in breast cancer by topically spraying, outperforming the clinical standard hematoxylin and eosin staining. We anticipate that the in-depth study of OTBP-G can prompt the development of early cancer diagnosis and tumor-related physiological research. Moreover, this work highlights the crucial role of hydrophilicity and donor-acceptor strength in maximizing the ON/OFF ratio of the TICT probes and showcases the potential of OTBP as a versatile platform for activity-based sensing.

Unrestricted molecular motions enable mild photothermy for recurrence-resistant FLASH antitumor radiotherapy.

Ultrahigh dose-rate (FLASH) radiotherapy is an emerging technology with excellent therapeutic effects and low biological toxicity. However, tumor recurrence largely impede the effectiveness of FLASH therapy. Overcoming tumor recurrence is crucial for practical FLASH applications. Here, we prepared an agarose-based thermosensitive hydrogel containing a mild photothermal agent (TPE-BBT) and a glutaminase inhibitor (CB-839). Within nanoparticles, TPE-BBT exhibits aggregation-induced emission peaked at 900 nm, while the unrestricted molecular motions endow TPE-BBT with a mild photothermy generation ability. The balanced photothermal effect and photoluminescence are ideal for phototheranostics. Upon 660-nm laser irradiation, the temperature-rising effect softens and hydrolyzes the hydrogel to release TPE-BBT and CB-839 into the tumor site for concurrent mild photothermal therapy and chemotherapy, jointly inhibiting homologous recombination repair of DNA. The enhanced FLASH radiotherapy efficiently kills the tumor tissue without recurrence and obvious systematic toxicity. This work deciphers the unrestricted molecular motions in bright organic fluorophores as a source of photothermy, and provides novel recurrence-resistant radiotherapy without adverse side effects.

Powerful Synergy of Traditional Chinese Medicine and Aggregation-Induced Emission-Active Photosensitizer in Photodynamic Therapy.

Breast cancer (BC) remains a significant global health challenge for women despite advancements in early detection and treatment. Isoliquiritigenin (ISL), a compound derived from traditional Chinese medicine, has shown potential as an anti-BC therapy, but its low bioavailability and poor water solubility restrict its effectiveness. In this study, we created theranostic nanoparticles consisting of ISL and a near-infrared (NIR) photosensitizer, TBPI, which displays aggregation-induced emission (AIE), with the goal of providing combined chemo- and photodynamic therapies (PDT) for BC. Initially, we designed an asymmetric organic molecule, TBPI, featuring a rotorlike triphenylamine as the donor and 1-methylpyridinium iodide as the acceptor, which led to the production of reactive oxygen species in mitochondria. We then combined TBPI with ISL and encapsulated them in DSPE-PEG-RGD nanoparticles to produce IT-PEG-RGD nanoparticles, which showed high affinity for BC, better intersystem crossing (ISC) efficiency, and Förster resonance energy transfer (FRET) between TBPI and ISL. In both 4T1 BC cell line and a 4T1 tumor-bearing BC mouse model, the IT-PEG-RGD nanoparticles demonstrated excellent drug delivery, synergistic antitumor effects, enhanced tumor-killing efficacy, and reduced drug dosage and side effects. Furthermore, we exploited the optical properties of TBPI with ISL to reveal the release process and distribution of nanoparticles in cells. This study provides a valuable basis for further exploration of IT-PEG-RGD nanoparticles and their anticancer mechanisms, highlighting the potential of theranostic nanoparticles in BC treatment.

In situ generation of highly localized chlorine by laser-induced graphene electrodes during electrochemical disinfection.

Laser-induced graphene (LIG) has gained popularity for electrochemical water disinfection due to its efficient antimicrobial activity when activated with low voltages. However, the antimicrobial mechanism of LIG electrodes is not yet fully understood. This study demonstrated an array of mechanisms working synergistically to inactivate bacteria during electrochemical treatment using LIG electrodes, including the generation of oxidants, changes in pH-specifically high alkalinity associated with the cathode, and electro-adsorption on the electrodes. All these mechanisms may contribute to the disinfection process when bacteria are close to the surface of the electrodes where inactivation was independent of the reactive chlorine species (RCS); however, RCS was likely responsible for the predominant cause of antibacterial effects in the bulk solution (i.e., ≥100 mL in our study). Furthermore, the concentration and diffusion kinetics of RCS in solution was voltage-dependent. At 6 V, RCS achieved a high concentration in water, while at 3 V, RCS was highly localized on the LIG surface but not measurable in water. Despite this, the LIG electrodes activated by 3 V achieved a 5.5-log reduction in Escherichia coli (E.coli) after 120-min electrolysis without detectable chlorine, chlorate, or perchlorate in the water, suggesting a promising system for efficient, energy-saving, and safe electro-disinfection.

Preparation of 2D Polyaniline/MoO3- x Superlattice Nanosheets via Intercalation-Induced Morphological Transformation for Efficient Chemodynamic Therapy.

Organic intercalation of layered nanomaterials is an attractive strategy to fabricate organic/inorganic superlattices for a wide range of promising applications. However, the synthesis of 2D organic/inorganic superlattice nanosheets remains a big challenge. Herein, the preparation of 2D polyaniline/MoO3- x (PANI/MoO3- x ) superlattice nanosheets via intercalation-induced morphological transformation from MoO3  nanobelts, as efficient Fenton-like reagents for chemodynamic therapy (CDT), is reported. Micrometer-long MoO3  nanobelts are co-intercalated with Na+ /H2 O followed by the guest exchange with aniline monomer for in situ polymerization to obtain PANI/MoO3- x nanosheets. Intriguingly, the PANI intercalation can induce the morphological transformation from long MoO3  nanobelts to 2D PANI/MoO3- x nanosheets along with the partial reduction of Mo6+ to Mo5+ , and generation of rich oxygen vacancies. More importantly, thanks to the PANI intercalation-induced activation, the PANI/MoO3- x nanosheets exhibit excellent Fenton-like catalytic activity for generation of hydroxyl radical (·OH) by decomposing H2 O2  compared with the MoO3  nanobelts. It is speculated that the good conductivity of PANI can facilitate electron transport during the Fenton-like reaction, thereby enhancing the efficiency of CDT. Thus, the polyvinylpyrrolidone-modified PANI/MoO3- x nanosheets can function as Fenton-like reagents for highly efficient CDT to kill cancer cells and eradicate tumors.

Impacts of shell structure on nitrate-reduction activity and air stability of nanoscale zero-valent iron.

Nanoscale zero-valent iron (nZVI) has been intensively studied for pollution control because of its high reductive activity and environmental benignity, but the poor reaction selectivity and the aging problem have limited its practical decontamination application. Here, we shed light on the impacts of nZVI shell structure on its reactivity and air stability by systematically comparing two nZVI materials with distinct iron oxide shells. The nZVI with highly crystalline and weakly hydrophilic shell exhibited ninefold higher intrinsic activity for nitrate reduction and significantly improved air stability than that with amorphous, hydrophilic iron hydroxide oxide shell. The compact-structured crystalline shell of nZVI facilitated more efficient interfacial electronic transfer for nitrate reduction and suppressed side reaction of hydrogen evolution. The protective hematite shell endowed the nZVI with significantly improved anti-aging ability, and the reducing force remained 92.6% after exposed to air for 10 days due to decreased oxygen diffusion. This work provides a better understanding of the pollutant degradation behavior of nZVI and may guide an improved synthesis and environmental application of nZVI.