Ultrasmall Au Research Articles

Ti3C2Tx/Au NPs/PPy ternary heterostructure-based intra-capacitive self-powered sensor for DEHP detection.

Phthalate esters, particularly di(2-ethylhexyl) phthalate (DEHP), are widely used plasticizers found in various consumer products, posing significant environmental and health risks due to their endocrine-disrupting effects. In this study, a novel enzyme-free intra-capacitive biofuel cell self-powered sensor (ICBFC-SPS) was developed. The ICBFC-SPS integrated a ternary heterostructure-based capacitive anode and a cathode with a sensing interface into a single-chamber electrolytic cell. The ternary heterostructure based on Ti3C2Tx MXene with ultra-small Au NPs and polypyrrole (PPy) NPs was prepared to provide the efficient glucose oxidation and robust electron production. Furthermore, the charge storage capacity was significantly enhanced through a synergistic combination of the double-layer capacitor mechanism of Ti3C2Tx and the pseudocapacitive behavior of PPy. Additionally, the intercalation of PPy NPs expanded the interlayer spacing, promoting electrolyte ion diffusion and charge transfer. The ICBFC-SPS demonstrated exceptional sensitivity with a linear detection range from 0.05 to 100000 ng/L and a detection limit of 9.51 pg/L for the sensitive and selective detection of DEHP in complex environmental and biological samples. The ICBFC-SPS addresses the limitations of traditional methods by providing a self-powered, highly sensitive, and portable platform for rapid, on-site DEHP detection. This work underscores the potential of self-powered sensors as transformative tools for real-time environmental monitoring and public health protection.

Gapped and Rotated Grain Boundary Revealed in Ultra-Small Au Nanoparticles for Enhancing Electrochemical CO2 Reduction.

Although gapped grain boundaries have often been observed in bulk and nanosized materials, and their crucial roles in some physical and chemical processes have been confirmed, their acquisition at ultrasmall nanoscale presents a significant challenge. To date, they had not been reported in metal nanoparticles smaller than 2 nm owing to the difficulty in characterization and the high instability of grain boundary (GB) atoms. Herein, we have successfully developed a synthesis method for producing a novel chiral nanocluster Au78(TBBT)40 (TBBT=4-tert-butylphenylthiolate) with a 26-atom gapped and rotated GB. This nanocluster was precisely characterized using single-crystal X-ray crystallography and mass spectrometry. Additionally, an offset atomic defect linked to the peripheral Au(TBBT)2 staple was found in the structure. Comparing it to similarly face-centered cubic-structured Au36(TBBT)24, Au44(TBBT)28, Au52(TBBT)32, Au92(TBBT)44, and ~5 nm nanocrystals, the bridging Au78(TBBT)40 nanocluster exhibited higher catalytic activity in the electroreduction of CO2 to CO. This enhanced activity was explained through density functional theory calculations and X-ray photoelectron spectroscopy analysis, which highlight the impact of GBs and point defects on the surface properties of metal nanoclusters in balancing intermediate adsorption and product desorption.

Expanding the Toolbox of Oxidants: Controllable Etching of Ultrasmall Au Nanoparticles toward Tailorable NIR-II Luminescence and Ligand-Mediated Biodistribution and Clearance.

Oxidant-driven and controllable etching of small-sized nanoparticles (NPs, d < 3 nm) and tailorable modulation of their optical properties are challenging due to the high reactivity and complicated surface chemistry. Herein, we present a facile strategy for highly controllable oxidative etching of ultrasmall AuNPs and tailorable modulation of luminescence. The proper choice of a moderate oxidant, ClO-, could not only selectively etch the Au(I)-thiolate motifs from the nanoparticle surface at the subnanometer scale but also retained a stable metallic core structure without aggregation, which impressively prompted the wide-range luminescent switching from the visible to second near-infrared (NIR-II) region. The resultant oxidized AuNPs displayed highly luminescent NIR-II emission with a quantum yield of 3.0%, excellent monodispersed stability, ideal biocompatibility, and tunable shielding effects against protein adsorption. With those outstanding features, oxidized AuNPs could be utilized as nanoprobes for long-lasting and in vivo bioimaging of associated metabolic behaviors with distinguishable organ-specific targeting capabilities and ligand-mediated kinetics in nanoparticle clearance. These findings expand the toolbox of oxidants for the controllable synthesis of NIR-II nanoprobes and open up a path for exploring diverse ligand interactions on ultrasmall AuNPs with organs or tissues that might advance their monitoring applications for a wide range of clinically important diseases.

Mxene-based capacitive enzyme-free biofuel cell Self-Powered sensor for lead ion detection in human plasma

In response to the health risks posed by heavy metal lead, we have developed a self-powered sensor specifically designed for detection of lead ions in this work. This sensor is designed based on an enzyme-free biofuel cell as a self-powered source. The biofuel cell utilizes two-dimensional lamellar Au NPs-Ti3C2Tx heterostructures as the capacitive anode substrate material. The Ti3C2Tx MXene with the excellent charge storage capacity and fast discharge characteristics, provides a large instantaneous current for signal amplification. Furthermore, the DNA walker technique was combined to regulate the loading of ultra-small Au NPs exhibiting glucose oxidase-like properties. Meanwhile, Co, Mn nitrogen-doped carbon-based nanosheets were designed as the cathode with outstanding oxygen reduction reaction catalytic activity. As a result, the constructed enzyme-free biofuel cell has been used to detect Pb2+ with a wide linear range (0.01–7500 nM) and a low detection limit (0.43 pM). It has been successfully applied to the determination of Pb2+ in human plasma, achieving excellent recovery rates (94.0–110.5 %). The developed capacitive anodes not only significantly optimized the performance of the biofuel cell self-powered sensors, but also provided important insights for the future design and construction of biofuel cells.

Synergy Between LSPR and Energy Transfer in Ultrasmall Au Nanoclusters Stabilized on Plasmonic Ag@SiO2 Nanoantenna Supports: Implication for Photocatalysis

Synergy Between LSPR and Energy Transfer in Ultrasmall Au Nanoclusters Stabilized on Plasmonic Ag@SiO₂ Nanoantenna Supports: Implication for Photocatalysis

Monodispersed and Monofunctionalized DNA-Caged Au Nano-Clusters with Enhanced Optical Properties for STED Imaging.

The performance of Stimulated Emission Depletion (STED) microscopy depends critically on the fluorescent probe. Ultrasmall Au nanoclusters (Au NCs) exhibit large Stokes shift, and good stimulated emission response, which are potentially useful for STED imaging. However, Au NCs are polydispersed in size, sensitive to the surrounding environment, and difficult to control surface functional group stoichiometry, which results in reduced density and high heterogeneity in the labeling of biological structures. Here, this limitation is overcome by developing a method to encapsulate ultrasmall Au NCs with DNA cages, which yielded monodispersed, and monofunctionalized Au NCs that are long-term stable. Moreover, the DNA-caging also greatly improved the fluorescence quantum yield and photostability of Au NCs. In STED imaging, the DNA-caged Au NCs yielded ≈40nm spatial resolution and are able to resolve microtubule line shapes with good labeling density and homogeneity. In contrast, without caging, the Au NCs-DNA conjugatesonly achieved ≈55nm resolution and yielded spotted,poorly resolved microtubule structures, due to the presence of aggregates. Overall, a method is developed to achieve precise surface functionalization and greatly improve the monodispersity, stability, as well as optical properties of Au NCs, providing a promising class of fluorescent probes for STED imaging.

Effective enrichment of glycated proteome using ultrasmall gold nanoclusters functionalized with boronic acid.

Glycated proteins play a crucial role in various biological pathways and the pathogenesis of human diseases. A comprehensive analysis of glycated proteins is essential for understanding their biological significance. However, their low abundance and heterogeneity in complex biological samples necessitate an enrichment procedure prior to their detection. Current enrichment strategies primarily rely on the boronic acid (BA) affinity method combined with functional nanoparticles; however, the effectiveness of these approaches is often suboptimal. In this study, a novel nanocluster (NC)-based enrichment material was synthesized for the first time, characterized as Au22SG18 functionalized with 24 BA groups, in which SG is glutathione. The functionalized BA established a reversible covalent bond with the cis-dihydroxy group through pH adjustment, enabling selective enrichment of glycated peptides. After the optimization of the enrichment protocol, we demonstrated highly sensitive and selective enrichment of standard glycopeptides using the NC-based enrichment material, exhibiting excellent reusability. Efficient enrichment was also demonstrated for the glycated proteome from human serum. These results highlight the potential of the atomically well-defined ultrasmall Au NCs as a powerful tool for high-throughput analysis of glycated peptides.

Multifunctional nanoplatform based on tetragonal BaTiO3-Au@polydopamine for computed tomography imaging-guided photothermal synergistic and enhanced piezocatalytic cancer therapy

Non-centrosymmetric tetragonal barium titanate nanocrystals have the potential to serve as piezoelectric catalysts in cancer therapy. When exposed to ultrasound irradiation, BaTiO3 can generate reactive oxygen species with a noninvasive and deep tissue-penetrating approach. However, the application of BaTiO3 in cancer nanomedicine is limited by their biosafety, biocompatibility, and dosage efficiency. To explore the potential application of BaTiO3 in nanomedical cancer treatment, we introduced ultra-small Au nanoparticles onto the surface of BaTiO3 to enhance the piezoelectric catalytic performance. Additionally, we also coated the BaTiO3 with polydopamine to improve their biosafety and biocompatibility. This led to the preparation of a novel multifunctional BaTiO3-based nanoplatform called BTAPs. In vitro and in vivo experiments demonstrated that the incorporation of Au dopants and polydopamine coating successfully improved the piezoelectric catalysis properties and biocompatibility of BaTiO3. Compared with unmodified BaTiO3, BTAPs achieved a similar piezoelectric catalytic effect at a low dose (0.3 mg ml−1 in vitro and 10 mg kg−1 in vivo). Moreover, BTAPs also exhibited enhanced properties in computed tomography imaging and photothermal effects in vivo. Therefore, BTAPs offer valuable insights into the advantages and limitations of piezoelectric catalytic nanomedicine in cancer treatment.

Metal-organic framework-modulated Fe3O4 composite au nanoparticles for antibacterial wound healing via synergistic peroxidase-like nanozymatic catalysis

Bacterial wound infections are a serious threat due to the emergence of antibiotic resistance. Herein, we report an innovative hybrid nanozyme independent of antibiotics for antimicrobial wound healing. The hybrid nanozymes are fabricated from ultra-small Au NPs via in-situ growth on metal-organic framework (MOF)-stabilised Fe3O4 NPs (Fe3O4@MOF@Au NPs, FMA NPs). The fabricated hybrid nanozymes displayed synergistic peroxidase (POD)-like activities. It showed a remarkable level of hydroxyl radicals (·OH) in the presence of a low dose of H2O2 (0.97 mM). Further, the hybrid FMA nanozymes exhibited excellent biocompatibility and favourable antibacterial effects against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The animal experiments indicated that the hybrid nanozymes promoted wound repair with adequate biosafety. Thus, the well-designed hybrid nanozymes represent a potential strategy for healing bacterial wound infections, without any toxic side effects, suggesting possible applications in antimicrobial therapy.

Phosphorylation of NIR‐II emitting Au nanoclusters for targeted bone imaging and improved rheumatoid arthritis therapy

AbstractDesigning a theranostic probe for noninvasive bone imaging and bone disease therapy is both challenging and desirable. Herein, an ultrasmall Au nanocluster (NC, &lt;2 nm)‐based theranostic probe is developed to achieve highly temporospatial in vivo bone‐targeted photoluminescence (PL) imaging in the second near‐infrared window (NIR‐II) and enhanced rheumatoid arthritis (RA) therapy. The key design of the probe involves the surface phosphorylation of atomically precise NIR‐II emitting Au44 NCs. This phosphorylation enhances the bone‐targeting ability of the probe due to the highly concentrated phosphate groups, allowing the probe to realize in vivo bone‐targeted NIR‐II PL imaging. Moreover, benefiting from the enhanced bone‐targeting ability, ultrasmall hydrodynamic diameter, and excellent anti‐inflammation and immunomodulatory effects, the probe not only demonstrates superior therapeutic efficacy for RA rats, effectively restoring the destructed cartilage to nearly normal but also exhibits good renal clearance and benign biocompatibility. These favorable attributes cannot be achieved by commercial methotrexate used for RA treatment. This study presents a new design paradigm for metal NC‐based theranostic probes, offering the potential for high‐resolution bone‐targeted PL imaging and improved RA therapy.

Rational fabrication of Ti0.69Zr0.31O2 modified Au-loaded halloysite core-shell catalyst for highly efficient reduction of 4-nitrophenol and dye pollutants

Catalytic reduction method can reductively degrade some highly toxic and harmful pollutants and transform them into useful chemical resources with low toxicity and easy biodegradability, owning the advantages of environmental friendliness, economic effectiveness and mild conditions. This study reported the rational fabrication of the HNTs-Au@Ti0.69Zr0.31O2 hollow tubular core-shell catalyst for facile reductive degradation of aqueous 4-nitrophenol and azo dye pollutants. The catalyst employed the interfacial reaction strategy for aminopropyl-functionalization of halloysite nanotubes as core, amino electrostatic adsorption and in situ redction of ultrasmall Au nanoparticles with good dispersibility, and sol-gel deposition of Ti0.69Zr0.31O2 shell. The obtained HNTs-Au@Ti0.69Zr0.31O2 catalyst manifested superior catalytic performance and atom utilization efficiency of Au active sites for reduction of 4-nitrophenol, methylene blue and methyl orange in comparison to those control samples. The integration of TiO2 and ZrO2 within Ti0.69Zr0.31O2 shell enriched the porosity of the catalyst, and generated the extraordinary interfacial chemical effect on Au NPs with improved surface electronic state. The interlayer-embedded Au nanoparticles were effectively solidified and avoided from agglomeration and loss, where the reactive electron migration rate from BH4- to target pollutants upon Au surfaces was elevated for prominent catalytic reaction rate. The unique structural characteristics and synergistic enhancement effect of catalyst components created excess catalytic active sites at the hybrid interface surrounded Au nanoparticles due to the strong metal-carrier chemical effect, and contributed to the construction of the high-performance catalytic system, which endowed the HNTs-Au@Ti0.69Zr0.31O2 catalyst with remarkable catalytic capability, reusability and structural stability. The reaction mechanism and structure-property relationship were finally proposed.

Clay-based durable catalyst membranes of porous layered double hydroxide and gold nanoparticle nanocomposites for fast and continuous-flow reactions

We synthesized the hybrid catalyst of a porous layered double hydroxide (LDH) decorated with ultrasmall Au nanoparticles. The porous LDH was prepared by coprecipitation and ethanol washing, producing thin LDH nanoplatelets. Thereafter, spray drying was carried out, affording a few hundred nm of the hydrangea-like structure of the LDH with an extensive open network and a Brunauer–Emmett–Teller surface area of 386 m2/g. Its sizable open frame and active hydroxide surface enabled the uniform decoration of average 4-nm-diameter Au nanoparticles (Au/P-LDH) through one-pot chemical reduction using NaBH4 at room temperature. We applied the Au/P-LDH for the fabrication of catalyst membranes, which are potentially valuable for the continuous flow of catalytic reactions, e.g., the hydrogenation of p-nitrophenol. This study suggested that their porous structure and active Au nanoparticle catalyst allowed fast and mass catalytic functions by simple filtration without washing or catalyst recovery steps. We found no significant damage to the hybrid membrane during the reactions with a few liters; thus, we expect strong bindings of the Au nanoparticles on the surface of the porous LDH.

Bifunctional Cascading Nanozymes Based on Carbon Dots Promotes Photodynamic Therapy by Regulating Hypoxia and Glycolysis.

Photodynamic therapy (PDT) still faces great challenges with suitable photosensitizers, oxygen supply, and reactive oxygen species (ROS) accumulation, especially in the tumor microenvironment, feathering hypoxia, and high glucose metabolism. Herein, a carbon dots (CDs)-based bifunctional nanosystem (MnZ@Au), acting as photosensitizer and nanozyme with cascading glucose oxidase (GOx)- and catalase (CAT)-like reactivity, was developed for improving hypoxia and regulating glucose metabolism to enhance PDT. The MnZ@Au was constructed using Mn-doped CDs (Mn-CDs) as a core and zeolitic imidazolate framework-8 (ZIF-8) as a shell to form a hybrid (MnZ), followed by anchoring ultrasmall Au nanoparticles (AuNPs) onto the surface of MnZ through the ion exchange and in situ reduction methods. MnZ@Au catalyzed glucose consumption and oxygen generation by cascading GOx- and CAT-like nanozyme reactions, which was further enhanced by its own photothermal properties. In vitro and in vivo studies also confirmed that MnZ@Au greatly improved CDs penetration, promoted ROS accumulation, and enhanced PDT efficacy, leading to efficient tumor growth inhibition in the breast tumor model. Besides, MnZ@Au enabled photoacoustic (PA) imaging to provide a mapping of Mn-CDs distribution and oxygen saturation, showing the real-time catalytic process of MnZ@Au in vivo. 18F-Fluorodeoxyglucose positron emission tomography (18F-FDG PET) imaging also validated the decreased glucose uptake in tumors treated by MnZ@Au. Therefore, the integrated design provided a promising strategy to utilize and regulate the tumor microenvironment, promote penetration, enhance PDT, and finally prevent tumor deterioration.

Engineering Au44 Nanoclusters for NIR-II Luminescence Imaging-Guided Photoactivatable Cancer Immunotherapy.

Immunotherapy is an advanced therapeutic strategy of cancer treatment but suffers from the issues of off-target adverse effects, lack of real-time monitoring techniques, and unsustainable response. Herein, an ultrasmall Au nanocluster (NC)-based theranostic probe is designed for second near-infrared window (NIR-II) photoluminescence (PL) imaging-guided phototherapies and photoactivatable cancer immunotherapy. The probe (Au44MBA26-NLG for short) is composed of atomically precise and NIR-II emitting Au44MBA26 NCs (here MBA denotes water-soluble 4-mercaptobenzoic acid) conjugated with immune checkpoint inhibitor 1-cyclohexyl-2-(5H-imidazo[5,1-a]isoindol-5-yl)ethanol (NLG919) via a singlet oxygen (1O2)-cleavable linker. Upon NIR photoirradiation, the Au44MBA26-NLG not only enables NIR-II PL imaging of tumors in deep tissues for guiding tumor therapy but also allows the leverage of photothermal property for cancer photothermal therapy (PTT) and the photogenerated 1O2 for photodynamic therapy (PDT) and releasing NLG919 for cancer immunotherapy. Such a multiple effect modulated by Au44MBA26-NLG prompts the proliferation and activation of effector T cells, upshifts systemic antitumor T-lymphocyte (T cell) immunity, and finally suppresses the growth of both primary and distant tumors in living mice. Overall, this study may provide a promising theranostic nanoplatform toward NIR-II PL imaging-guided phototherapies and photoactivatable cancer immunotherapy.

Potentiating Tweezer Affinity to a Protein Interface with Sequence-Defined Macromolecules on Nanoparticles.

Survivin, a well-known member of the inhibitor of apoptosis protein family, is upregulated in many cancer cells, which is associated with resistance to chemotherapy. To circumvent this, inhibitors are currently being developed to interfere with the nuclear export of survivin by targeting its protein-protein interaction (PPI) with the export receptor CRM1. Here, we combine for the first time a supramolecular tweezer motif, sequence-defined macromolecular scaffolds, and ultrasmall Au nanoparticles (us-AuNPs) to tailor a high avidity inhibitor targeting the survivin-CRM1 interaction. A series of biophysical and biochemical experiments, including surface plasmon resonance measurements and their multivalent evaluation by EVILFIT, reveal that for divalent macromolecular constructs with increasing linker distance, the longest linkers show superior affinity, slower dissociation, as well as more efficient PPI inhibition. As a drawback, these macromolecular tweezer conjugates do not enter cells, a critical feature for potential applications. The problem is solved by immobilizing the tweezer conjugates onto us-AuNPs, which enables efficient transport into HeLa cells. On the nanoparticles, the tweezer valency rises from 2 to 16 and produces a 100-fold avidity increase. The hierarchical combination of different scaffolds and controlled multivalent presentation of supramolecular binders was the key to the development of highly efficient survivin-CRM1 competitors. This concept may also be useful for other PPIs.

Mechanochemically activated Au/CeO2 for enhanced CO oxidation and COPrOx reaction

COPrOx reaction is one of the particularly appealing and cost-effective solutions for the selective oxidation of CO in hydrogen-rich gas streams to meet the stringent requirement of the current electrocatalysts employed in low-temperature fuel cells. Herein, we synthesized ultrasmall Au clusters supported on ceria by one-step solvent-free mechanochemical method. These catalysts exhibited higher activity for COPrOx and CO oxidation compared to the sample prepared by conventional incipient wetness impregnation. The unique Au-Ce interaction caused by impact and friction between the ball, vessel, and powders, greatly promotes the generation of positive charged Auδ+ active sites and, at the same time, the reducibility of the catalyst. Interestingly, an aging treatment of the ball-milled samples resulted in a significant superior performance of the catalytic activity. This enhancement has been attributed to a change in the oxidation state of Au between the fresh and the aged catalysts prepared by ball milling.

Gold Au(I)6 Clusters with Ligand‐Derived Atomic Steric Locking: Multifunctional Optoelectrical Properties and Quantum Coherence

AbstractAn atomically precise ultrasmall Au(I)6 nanocluster where the six gold atoms are complexed by three sterically interlocking stabilizing ligands is reported, allowing a unique combination of efficient third harmonic generation (THG), intense photoluminescence quantum yield (35%), ultrafast quantum coherence, and electron accepting properties. The reaction of 6‐(dibutylamino)‐1,3,5‐triazine‐2,4‐dithiol (TRZ) with HAuCl4 leads to complexation by thiolation. However, intriguingly, another reduction step is needed to form the centrosymmetric Au(I)6TRZ3 clusters with the multifunctional properties. Here, ascorbic acid is employed as a mild reducing agent, in contrast to the classic reducing agents, like NaBH4 and NaBH3CN, which often produce mixtures of clusters or gold nanoparticles. Such Au(I)6 nanocluster films produce very strong THG response, never observed for nanoclusters. The clusters also produce brilliant single and multiphoton luminescence with exceptional stability. Density functional theory calculations and femtosecond transient absorption studies suggest ultrafast ligand‐to‐metal charge transfer, quantum coherence with long decoherence time 200–300 fs, and fast propagation of excitation from the core to the surrounding solvent. Finally, novel electron‐accepting ground state properties allow p‐doping of 2D field‐effect transistor devices. Summarizing, the potential of ultrasmall sterically interlocked Au(I) clusters, i.e., complexes allowed by the new sequential reduction protocol, towards multifunctional devices, fast photoswitches, and quantum colloidal devices is shown.

Enhancement of photocatalytic ammonia production over BiOBr nanosheets with photo-assembled Au cocatalysts

Noble metal loading has emerged as a promising approach to improve the activity of photocatalysts by promoting charge separation. However, the enhancement effect is highly dependent on the size of metal cocatalysts and interface parameters at nanoscales. Herein, a solid-phase light-driven process was conducted to construct ultrasmall Au nanococataysts from atomically dispersed Au clusters on BiOBr nanosheets. Based on the experiments of N2 photoreduction, the solid-state reconstruction of Au cocatalysts with the assistance of light significantly improved their activity for NH3 production. The photo-assembled BiOBr/Au-CP with both Au culsters and nanoparticles exhibited a striking NH3 evolution rate, superior to BiOBr/Au-C with only atomically dispersed Au and traditional BiOBr/Au-T with only larger photodeposited Au nanoparticles. This study provides a facile bottom-up strategy to precisely control the site activity around the semiconductor/cocatalyst interface at the atomic level.

Rapid biosynthesis and characterization of metallic gold nanoparticles by olea europea and their potential application in photoelectrocatalytic reduction of 4-nitrophenol

In recent years, photoelectrocatalysis of gold nanoparticles (Au NPs) has received considerable attention due to their potential to improve catalytic efficiency. Herein, ultra-small Au NPs were successfully synthesized in a single pot using olea europea leaf extract as a green reducing agent for the degradation of 4-nitrophenol. The TEM images showed uniform distribution and spherical shape of Au NPs with an average diameter of 5 nm. Taking advantage of the ability of Au nanoparticles to absorb visible and near-infrared light, 4-nitrophenol can be successfully reduced in the presence of NaBH4. Additionally, the electrochemical activity of the fabricated Au photocathode was investigated by linear sweep voltammetry in the dark and at VIS-NIR light irradiation. This showed an increased photocurrent density of 27 mA cm−2 with an onset potential of −0.71 V. This indicates that the Au photocathode is highly active at VIS-NIR light. Interestingly, the Au photocathode showed a higher current density of 37 mA cm−2 with an onset potential of −0.6 V in the presence of 4-nitrophenol during VIS-NIR irradiation, indicating that 4-nitrophenol was efficiently reduced by the photocathode. The Au photocathode completely reduced 4-nitrophenol in the wastewater within 35 min. Recyclability studies showed that the Au NPs photocathode exhibited higher stability over multiple cycles, confirming the ability of the electrode to treat wastewater over a longer period of time. This study demonstrates the effectiveness of the photoelectrochemical (PEC) process in reducing organic compounds in wastewater.

Epigenetic reprogramming of cancer stem cells to tumor cells using ultrasmall gold nanoparticle

Epigenetic reprogramming of cancer stem-like cells (CSC) is crucial to the clinical implementation of efficient tumor management. Groups of methylation on genomic DNA are a relatively stable epigenetic component. They are key drivers in the formation and maintenance of CSCs. Hence, reprogramming the DNA methylation epigenetics can provide new insights into cancer therapeutic approaches. Nanoprobes can influence CSC epigenetics; however, existing nanoprobes induce epigenetic alterations in an unregulated manner, which might result in undesirable mutation accumulation, which can hinder the reprogramming process. Here we report an epigenetic reprogramming approach with an ultrasmall Au NP, which can demethylate the genomic DNA, thereby causing the reprogramming of CSCs to cancer cells. In vitro bench top verification on preclinical models of non-metastatic and metastatic lung CSC showed a significant decrease in genetic, phenotypic stemness, and cell cycle quiescence, validated with biological assays. Furthermore, the ultrasmall Au NP was shown to interact with the epigenetic environment of CSCs through gold-DNA affinity spectral analysis. The pilot clinical validation study established the potential of our approach for clinical implementation. To the best of our knowledge, this is the first study to demonstrate a CSC epigenetic reprogramming using nanoparticles. In summary, this paper demonstrated that the nanoprobe could actively modify epigenetics and, as a result, can be employed to mitigate CSC stemness. Our findings might pave the path for more effective anti-cancer treatments and precision nanomedicine in the future.