Metallacage-based enhanced PDT strategy for bacterial elimination via inhibiting endogenous NO production.

Antibiotics are among the most used weapons in fighting microbial infections and have greatly improved the quality of human life. However, bacteria can eventually evolve to exhibit antibiotic resistance to almost all prescribed antibiotic drugs. Photodynamic therapy (PDT) develops little antibiotic resistance and has become a promising strategy in fighting bacterial infection. To augment the killing effect of PDT, the conventional strategy is introducing excess ROS in various ways, such as applying high light doses, high photosensitizer concentrations, and exogenous oxygen. In this study, we report a metallacage-based PDT strategy that minimizes the use of ROS by jointly using gallium-metal organic framework rods to inhibit the production of bacterial endogenous NO, amplify ROS stress, and enhance the killing effect. The augmented bactericidal effect was demonstrated both in vitro and in vivo. This proposed enhanced PDT strategy will provide a new option for bacterial ablation.

Understanding Trap States in InP and GaP Quantum Dots through Density Functional Theory.

The widespread application of III-V colloidal quantum dots (QDs) as nontoxic, highly tunable emitters is stymied by their high density of trap states. Here, we utilize density functional theory (DFT) to investigate trap state formation in a diverse set of realistically passivated core-only InP and GaP QDs. Through orbital localization techniques, we deconvolute the dense manifold of trap states to allow for detailed assignment of surface defects. We find that the three-coordinate species dominate trapping in III-V QDs and identify features in the geometry and charge environment of trap centers capable of deepening, or sometimes passivating, traps. Furthermore, we observe stark differences in surface reconstruction between InP and GaP, where the more labile InP reconstructs to passivate three-coordinate indium at the cost of distortion elsewhere. These results offer explanations for experimentally observed trapping behavior and suggest new avenues for controlling trap states in III-V QDs.

Antimicrobial Activity of Gallium(III) Compounds: Pathogen-Dependent Targeting of Multiple Iron/Heme-Dependent Biological Processes.

Metals play vital roles in biological systems, with iron/heme being essential for cellular and metabolic functions necessary for survival and/or virulence in many bacterial pathogens. Given the rise of bacterial resistance to current antibiotics, there is an urgent need for the development of non-toxic and novel antibiotics that do not contribute to resistance to other antibiotics. Gallium, which mimics iron, has emerged as a promising antimicrobial agent, offering a novel approach to combat bacterial infections. Gallium does not have any known functions in biological systems. Gallium exerts its effects primarily by replacing iron in redox enzymes, effectively inhibiting bacterial growth by targeting multiple iron/heme-dependent biological processes and suppressing the development of drug resistance. The aim of this review is to highlight recent findings on the mechanisms of action of gallium and provide further insights into the development of gallium-based compounds. Understanding the mechanisms underlying gallium's biological activities is crucial for designing drugs that enhance their therapeutic therapies while minimizing side effects, offering promising avenues for the treatment of infectious diseases.

Gelatin-mediated gallium-doped SrHA composite coatings with sequential antimicrobial and osteogenic functions for infected bone defect repair.

In this study, gallium- and gelatin-modified strontium-doped hydroxyapatite (SrHA-Gel-Ga) bilayer coatings were prepared on titanium substrates by electrodeposition and spin-coating techniques. The results showed that gallium and gelatin were uniformly doped into the SrHA coatings, which exhibited good hydrophilicity and bioactivity. Furthermore, SrHA-Gel-Ga demonstrated good antimicrobial properties against E. coli and S. aureus, especially S. aureus. The co-doping of Sr and gelatin in the coatings was effective in mitigating the cytotoxicity of Ga. SrHA-Gel-Ga was better able to promote the adhesion, proliferation and early differentiation of MC3T3-E1 cells. This study provides a new strategy for the development of anti-infective bone repair coatings.

Interaction of gallium, indium, and vanadyl curcumin complexes with hen egg-white lysozyme (HEWL): Mechanistic aspects and evaluation of antiamyloidogenic activity.

Many proteins and peptides can aggregate into amyloid fibrils with high-ordered and cross-ß rich structure characteristics. Amyloid deposition is a common feature of neurodegenerative diseases called amyloidosis. Various natural polyphenolic compounds such as curcumin exhibited antiamyloidogenic activities, but less researches were focused on the metal complexes of these compounds. In this study, the inhibitory effects of gallium curcumin (Ga(cur)3), indium curcumin (In(cur)3), and vanadyl curcumin (VO(cur)2) on the amyloid fibrillation of hen egg white lysozyme (HEWL) have been investigated. Moreover, the details of binding interactions of these metal complexes with HEWL have been explored. The results of fluorescence quenching analyses revealed that In(cur)3 and VO(cur)2 have much higher binding affinities than Ga(cur)3 toward HEWL. The interactions of these metal complexes were accompanied by partial conformational changes in the tertiary structure of HEWL. The kinetic curves of the fibrillation process demonstrated that In(cur)3 and VO(cur)2 have higher inhibitory effects than Ga(cur)3 on the amyloid fibrillation of HEWL. The strength of binding to HEWL is completely in accordance with inhibitory activities of these metal complexes of curcumin.

Deterministic Fabrication of Liquid Metal Nanopatterns for Nanophotonics Applications.

Gallium-based liquid metals (LMs) are widely used for stretchable and reconfigurable electronics thanks to their fluidic nature and excellent conductivity. These LMs possess attractive optical properties for photonics applications as well. However, due to the high surface tension of the LMs, it is challenging to form LM nanostructures with arbitrary shapes using conventional nanofabrication techniques. As a result, LM-based nanophotonics has not been extensively explored. Here, a simple yet effective technique is demonstrated to deterministically fabricate LM nanopatterns with high yield over a large area. This technique demonstrates for the first time the capability to fabricate LM nanophotonic structures of various precisely defined shapes and sizes using two different LMs, that is, liquid gallium and liquid eutectic gallium-indium alloy. High-density arrays of LM nanopatterns with critical feature sizes down to ≈100 nm and inter-pattern spacings down to ≈100 nm are achieved, corresponding to the highest resolution of any LM fabrication technique developed to date. Additionally, the LM nanopatterns demonstrate excellent long-term stability under ambient conditions. This work paves the way toward further development of a wide range of LM nanophotonics technologies and applications.

Wafer-Scale Two-Dimensional Semiconductors for Deep UV Sensing.

2D semiconductors (2SEM) can transform many sectors, from information and communication technology to healthcare. To date, top-down approaches to their fabrication, such as exfoliation of bulk crystals by "scotch-tape," are widely used, but have limited prospects for precise engineering of functionalities and scalability. Here, a bottom-up technique based on epitaxy is used to demonstrate high-quality, wafer-scale 2SEM based on the wide band gap gallium selenide (GaSe) compound. GaSe layers of well-defined thickness are developed using a bespoke facility for the epitaxial growth and in situ studies of 2SEM. The dominant centrosymmetry and stacking of the individual van der Waals layers are verified by theory and experiment; their optical anisotropy and resonant absorption in the UV spectrum are exploited for photon sensing in the technological UV-C spectral range, offering a scalable route to deep-UV optoelectronics.

Implantation of Gallium into Layered WS2 Nanostructures is Facilitated by Hydrogenation.

Bombarding WS2 multilayered nanoparticles and nanotubes with focused ion beams of Ga+ ions at high doses, larger than 1016 cm-2, leads to drastic structural changes and melting of the material. At lower doses, when the damage is negligible or significantly smaller, the amount of implanted Ga is very small. A substantial increase in the amount of implanted Ga, and not appreciable structural damage, are observed in nanoparticles previously hydrogenated by a radio-frequency activated hydrogen plasma. Density functional calculations reveal that the implantation of Ga in the spaces between adjacent layers of pristine WS2 nanoparticles is difficult due to the presence of activation barriers. In contrast, in hydrogenated WS2, the hydrogen molecules are able to intercalate in between adjacent layers of the WS2 nanoparticles, giving rise to the expansion of the interlayer distances, that in practice leads to the vanishing of the activation barrier for Ga implantation. This facilitates the implantation of Ga atoms in the irradiation experiments.

Epitaxy of GaSe Coupled to Graphene: From In Situ Band Engineering to Photon Sensing.

2D semiconductors can drive advances in quantum science and technologies. However, they should be free of any contamination; also, the crystallographic ordering and coupling of adjacent layers and their electronic properties should be well-controlled, tunable, and scalable. Here, these challenges are addressed by a new approach, which combines molecular beam epitaxy and in situ band engineering in ultra-high vacuum of semiconducting gallium selenide (GaSe) on graphene. In situ studies by electron diffraction, scanning probe microscopy, and angle-resolved photoelectron spectroscopy reveal that atomically-thin layers of GaSe align in the layer plane with the underlying lattice of graphene. The GaSe/graphene heterostructure, referred to as 2semgraphene, features a centrosymmetric (group symmetry D3d) polymorph of GaSe, a charge dipole at the GaSe/graphene interface, and a band structure tunable by the layer thickness. The newly-developed, scalable 2semgraphene is used in optical sensors that exploit the photoactive GaSe layer and the built-in potential at its interface with the graphene channel. This proof of concept has the potential for further advances and device architectures that exploit 2semgraphene as a functional building block.

CO2 Stress-Driven Room Temperature Ferromagnetism of Ultrathin 2D Gallium Oxide.

Spintronic devices work by manipulating the spin of electrons other than charge transfer, which is of revolutionary significance and can largely reduce energy consumption in the future. Herein, ultrathin two-dimensional (2D) non-van der Waals (non-vdW) γ-Ga2O3 with room temperature ferromagnetism is successfully obtained by using supercritical CO2 (SC CO2). The stress effect of SC CO2 under different pressures selectively modulates the orientation and strength of covalent bonds, leading to the change of atomic structure including lattice expansion, introduction of O vacancy, and transition of Ga-O coordination (GaO4 and GaO6). Magnetic measurements show that pristine γ-Ga2O3 is nonferromagnetic, whereas the SC CO2 treated γ-Ga2O3 exhibits obvious ferromagnetic behavior with an optimal magnetization of 0.025 emu g-1 and a Curie temperature of 300 K.

Synthesis of 2D Gallium Sulfide with Ultraviolet Emission by MOCVD.

Two-dimensional (2D) materials exhibit the potential to transform semiconductor technology. Their rich compositional and stacking varieties allow tailoring materials' properties toward device applications. Monolayer to multilayer gallium sulfide (GaS) with its ultraviolet band gap, which can be tuned by varying the layer number, holds promise for solar-blind photodiodes and light-emitting diodes as applications. However, achieving commercial viability requires wafer-scale integration, contrasting with established, limited methods such as mechanical exfoliation. Here the one-step synthesis of 2D GaS is introduced via metal-organic chemical vapor deposition on sapphire substrates. The pulsed-mode deposition of industry-standard precursors promotes 2D growth by inhibiting the vapor phase and on-surface pre-reactions. The interface chemistry with the growth of a Ga adlayer that results in an epitaxial relationship is revealed. Probing structure and composition validate thin-film quality and 2D nature with the possibility to control the thickness by the number of GaS pulses. The results highlight the adaptability of established growth facilities for producing atomically thin to multilayered 2D semiconductor materials, paving the way for practical applications.

Versatile Patterning of Liquid Metal via Multiphase 3D Printing.

This paper presents a scalable and straightforward technique for the immediate patterning of liquid metal/polymer composites via multiphase 3D printing. Capitalizing on the polymer's capacity to confine liquid metal (LM) into diverse patterns. The interplay between distinctive fluidic properties of liquid metal and its self-passivating oxide layer within an oxidative environment ensures a resilient interface with the polymer matrix. This study introduces an inventive approach for achieving versatile patterns in eutectic gallium indium (EGaIn), a gallium alloy. The efficacy of pattern formation hinges on nozzle's design and internal geometry, which govern multiphase interaction. The interplay between EGaIn and polymer within the nozzle channels, regulated by variables such as traverse speed and material flow pressure, leads to periodic patterns. These patterns, when encapsulated within a dielectric polymer polyvinyl alcohol (PVA), exhibit an augmented inherent capacitance in capacitor assemblies. This discovery not only unveils the potential for cost-effective and highly sensitive capacitive pressure sensors but also underscores prospective applications of these novel patterns in precise motion detection, including heart rate monitoring, and comprehensive analysis of gait profiles. The amalgamation of advanced materials and intricate patterning techniques presents a transformative prospect in the domains of wearable sensing and comprehensive human motion analysis.

3D Printed Gallium Battery with Outstanding Energy Storage: Toward Fully Printed Battery-on-the-Board Soft Electronics.

The last decade observed rapid progress in soft electronics. Yet, the ultimate desired goal for many research fields is to fabricate fully integrated soft-matter electronics with sensors, interconnects, and batteries, at the ease of pushing a print button. In this work, an important step is taken toward this by demonstrating an ultra-stretchable thin-film Silver-Gallium (Ag-Ga) battery with an unprecedented combination of areal capacity and mechanical strain tolerance. The Biphasic Gallium-Carbon anode electrode demonstrates a record-breaking areal capacity of 78.7 mAh cm-2, and an exceptional stretchability of 170%, showing clear progress over state-of-the-art. The exceptional theoretical capacity of gallium, along with its natural liquid phase self-healing, and its dendrite-free operation permits excellent electromechanical cycling. All composites of the battery including liquid-metal-based current collectors, and electrodes are sinter-free and digitally printable at room temperature, enabling the use of a wide range of substrates, including heat-sensitive polymer films. Consequently, it is demonstrated for the first time multi-layer, and multi-material digital printing of complex battery-on-the-board stretchable devices that integrate printed sensor, multiple cells of printed battery, highly conductive interconnects, and silicone chips, and demonstrate a tailor-made patch for body-worn electrophysiological monitoring.

Wafer Scale Gallium Nitride Integrated Electrode Toward Robust High Temperature Energy Storage.

Gallium Nitride (GaN), as the representative of wide bandgap semiconductors, has great prospects in accomplishing rapid charge delivery under high-temperature environments thanks to excellent structural stability and electron mobility. However, there is still a gap in wafer-scale GaN single-crystal integrated electrodes applied in the energy storage field. Herein, Si-doped GaN nanochannel with gallium oxynitride (GaON) layer on a centimeter scale (denoted by GaN NC) is reported. The Si atoms modulate electronic redistribution to improve conductivity and drive nanochannel formation. Apart from that, the distinctive nanochannel configuration with a GaON layer provides adequate active sites and extraordinary structural stability. The GaN-based supercapacitors are assembled and deliver outstanding charge storage capabilities at 140 °C. Surprisingly, 90% retention is maintained after 50 000 cycles. This study opens the pathway toward wafer-scale GaN single-crystal integrated electrodes with self-powered characteristics that are compatible with various (opto)-electronic devices.

Quantitative proteomic analysis reveals Ga(III) polypyridyl catecholate complexes disrupt Aspergillus fumigatus mitochondrial function.

Infections caused by the airborne fungal pathogen, Aspergillus fumigatus, are increasing in severity due to growing numbers of immunocompromised individuals and the increasing incidence of antifungal drug resistance, exacerbating treatment challenges. Gallium has proven to be a strong candidate in the fight against microbial pathogens due to its iron-mimicking capability and substitution of Ga(III) in place of Fe(III), disrupting iron-dependent pathways. Since the antimicrobial properties of 2,2'-bipyridine and derivatives have been previously reported, we assessed the in vitro activity and proteomic effects of a recently reported heteroleptic Ga(III) polypyridyl catecholate compound against A. fumigatus. This compound has demonstrated promising growth-inhibition and impact on the A. fumigatus proteome compared to untreated controls. Proteins associated with DNA replication and repair mechanisms along with lipid metabolism and the oxidative stress responses were elevated in abundance compared to control. Crucially, a large number of mitochondrial proteins were reduced in abundance. Respiration is an important source of energy to fuel metabolic processes required for growth, survival and virulence, the disruption of which may be a viable strategy for the treatment of microbial infections.

Homodimeric peptide radiotracer [68Ga]Ga-NOTA-(TMVP1)2 for VEGFR-3 imaging of cervical cancer patients.

PURPOSE: Vascular endothelial growth factor receptor 3 (VEGFR-3) plays a critical role in tumor lymphangiogenesis and metastasis, holding promise as a promising therapeutic target for solid tumors. TMVP1 (LARGR) is a 5-amino acid peptide previously identified in our laboratory from bacterial peptide display system that specifically targets VEGFR-3. Radiolabeled TMVP1 can be used for non-invasive imaging of VEGFR-3 expressing tumors. Homodimeric peptides have better targeting ability than monomeric peptides, and it is worth exploring whether homodimers of TMVP1 ((TMVP1)2) can achieve better imaging effects. This study aimed to explore the peptide properties and tumor assessment value of [68Ga]Ga-labeled (TMVP1)2. METHODS: In this study, we developed a TMVP1 homodimer that was conjugated with 1,4,7-triazacyclononane-N, N', N″-triacetic acid (NOTA) via tetraethyleneglycol (PEG4) and triglyicine (Gly3) spacer, and labeled with 68Ga, to construct [68Ga]Ga-NOTA-(TMVP1)2. Binding of VEGFR-3 by TMVP1 and (TMVP1)2, respectively, was modeled by molecular docking. The affinity of [68Ga]Ga-NOTA-(TMVP1)2 for VEGFR-3 and its ability to bind to cells were evaluated. MicroPET imaging and biodistribution studies of [68Ga]Ga-NOTA-(TMVP1)2 were performed in subcutaneous C33A cervical cancer xenografts. Five healthy volunteers and eight patients with cervical cancer underwent whole-body PET/CT acquisition 30-45 min after intravenous injection of [68Ga]Ga-NOTA-(TMVP1)2. RESULTS: Both molecular docking and cellular experiments showed that homodimeric TMVP1 had a higher affinity for VEGFR-3 than monomeric TMVP1. [68Ga]Ga-NOTA-(TMVP1)2 was excreted mainly through the renal route and partly through the liver route. In mice bearing C33A xenografts, [68Ga]Ga-NOTA-(TMVP1)2 specifically localized in the tumor (2.32 ± 0.10% ID/g). Pretreatment of C33A xenograft mice with the unlabeled peptide NOTA-(TMVP1)2 reduced the enrichment of [68Ga]Ga-NOTA-(TMVP1)2 in tumors (0.58 ± 0.01% ID/g). [68Ga]Ga-NOTA-(TMVP1)2 proved to be safe in all healthy volunteers and recruited patients, with no side effects or allergies noted. In cervical cancer patients, a majority of the [18F]-FDG identified lesions (18/22, 81.8%) showed moderate to high signal intensity on [68Ga]Ga-NOTA-(TMVP1)2. SUVmax and SUVmean were 2.32 ± 0.77 and 1.61 ± 0.48, respectively. With normal muscle (gluteus maximus) as background, tumor-to-background ratios were 3.49 ± 1.32 and 3.95 ± 1.64 based on SUVmax and SUVmean, respectively. CONCLUSION: The favorable characterizations of [68Ga]Ga-NOTA-(TMVP1)2 such as convenient synthesis, high specific activity, and high tumor uptake enable the evaluation of VEGFR-3 in cervical cancer patients and warrant further clinical studies. TRIAL REGISTRATION: ChiCTR-DOD-17012458. Registered August 23, 2017 (retrospectively registered).

A Rare Example of a Gallium-based Lewis Superacid: Synthesis and Reactivity of Ga(OTeF5)3.

The Lewis superacid Ga(OTeF5)3 has been synthesized and characterized, revealing a monomeric structure in solution and a dimeric structure in the solid state. Isolated adducts of Ga(OTeF5)3 with strong and weak Lewis bases have been characterized spectroscopically as well as single-crystal X-ray diffractometry. The Lewis acidity of this new species has been evaluated by means of different experimental and theoretical methods, which has allowed to classify it as one of only a few examples of a gallium-based Lewis superacid. The high Lewis acidity of Ga(OTeF5)3 was used to amplify the strength of the Brønsted acid HOTeF5, leading to the protonation of diethyl ether. Furthermore, Ga(OTeF5)3 was utilized to access the strong oxidizing system Ga(OTeF5)3/Xe(OTeF5)2 in SO2ClF, which was successfully employed in the synthesis of the dimethyl chloronium salt [Cl(CH3)2][Ga(OTeF5)4], a strong electrophilic methylation reagent.

Base-Stabilized Gallium Sulfides and Selenides Supported by a Bis(oxazolinyl)(phenyl)methanide Ligand.

Gallylene supported by a bis(oxazolinyl)(phenyl)methanide (Boxm) ligand was synthesized and structurally characterized. The reaction of this gallylene with triphenylphosphine sulfide/selenide yielded dimeric gallium sulfide and selenide. These compounds could be converted to monomeric terminal sulfide and selenide by coordination of an external Lewis base such as an N-heterocyclic carbene (NHC or IMe4) and 4-dimethylaminopyridiene (DMAP). These doubly-base-stabilized gallium sulfide/selenide reacted with phenyl isocyanate to give the corresponding cycloadducts by releasing the Lewis base, indicating the formation of a single-base-stabilized gallium sulfide/selenide intermediate.

Reactivity of a Neutral Yttrium(III) Trimethyl Complex toward Brønsted and Lewis Acids.

The present study corroborates that the neutral tridentate N-ligand 1,4,7-trimethyl-triazacyclononane (Me3TACN) qualifies as a versatile platform to study selective ligand exchange with rare-earth-metal alkyl complexes, herein [(Me3TACN)YMe3]. Treatment with Brønsted-acidic bis(dimethylsilyl)amine, HN(SiHMe2)2, gave selectively the mono-exchanged heteroleptic complex [(Me3TACN)YMe2{N(SiHMe2)2}]. Depending on the molecular ratio employed, the reaction of [(Me3TACN)YMe3] with AlMe3 resulted in the isolation/crystallization of [(Me3TACN)YMe2(AlMe4)] [1 : 1] or ion-separated [(Me3TACN)YMe(AlMe4)][AlMe4] [1 : 2] and [(Me3TACN)YMe(AlMe4)][Al2Me7] [1 : 3]. Analogous reactions with the heavier group 13 methyls GaMe3 and InMe3 generated mixed methyl/tetramethylgallato complex [(Me3TACN)YMe2(GaMe4)] and ion-separated [{(Me3TACN)YMe2}2{µ-Me}][InMe4]. Finally, dimethylalane, HAlMe2, converted [(Me3TACN)YMe3] into heteroaluminate [(Me3TACN)Y(HAlMe3)3], representing an AlMe3-supported, molecular yttrium trihydride complex. All compounds were investigated by single crystal X-ray diffraction (SC-XRD), homo- and heteronuclear (13C, 27Al, 89Y, 115In) NMR as well as IR spectroscopies and elemental analyses.

Gallaphosphene L(Cl)GaPGaL: A novel phosphinidene transfer reagent.

Gallaphosphene L(Cl)GaPGaL 1 (L=HC[C(Me)N(Ar)]2; Ar=2,6-iPr2C6H3) reacts with N-heterocyclic carbenes RNHC (RNHC=[CMeN(R)]2C; R=Me, iPr) to RNHC-coordinated phosphinidenes RNHC→PGa(Cl)L (R=Me 2 a, iPr 2 b) and with isonitriles RNC (R=iPr, Cy) to 1,3-phosphaazaallenes L(Cl)GaP=C=N-R (R=iPr 3 a, Cy 3 b), respectively. Quantum chemical calculations reveal that 2 a/2 b possess two localized lone pair of electrons, whereas 3 a/3 b only show one localized lone pair as was reported for gallaphosphene 1. 2 b reacts with 2.5 equivalents of a borane (THF ⋅ BH3) to the NHC-stabilized phosphinidene-borane complex [iPrNHC→P(BH2)]2(BH3)3 4 with concomitant formation of LGa(H)Cl 5. 2-5 are characterized by heteronuclear (1H, 13C{1H}, 31P{1H}) NMR and IR spectroscopy, elemental analysis, and single crystal X-ray diffraction (sc-XRD).