Crystalline and amorphous structure selectivity of ignoble high-entropy alloy nanoparticles during laser ablation in organic liquids is set by pulse duration.

High-entropy alloy nanoparticles (HEA NPs) represent a promising material class with significant potential in various applications, such as heterogeneous catalysis or magnetic devices. This is due to their exceptional compositional tunability arising from the synergistic interplay of multiple elements within a single particle. While laser-synthesized, surfactant-free colloidal HEA NPs have already been reported, the underlying formation mechanism remains unknown, particularly the underexplored preference of amorphous over crystalline structures warrants further investigation.

Efficiency of single-pulse laser fragmentation of organic nutraceutical dispersions in a circular jet flow-through reactor.

Nutraceuticals provide health benefits and particularly profit from a sensitive, high-purity production process. Microparticle laser fragmentation in liquids is an emerging technique for the contamination-free comminution of organic drugs and nutraceuticals aiming at solubility enhancements. However, current discontinuously operated fragmentation setups suffer from chemical degradation by multipulse laser excitation at high fluence and do not allow for systematic studies of the fragmentation mechanisms.

Size control of nanoparticles synthesized by pulsed laser ablation in liquids using donut-shaped beams.

The potential to modify the size distribution of nanoparticles synthesized by pulsed laser ablation in liquids is demonstrated using a donut-shaped laser beam. In experiments on pulsed laser ablation in water of gold, yttrium oxide, and high-entropy alloy targets with both Gaussian and donut-shaped beams, we observed a significant reduction in particle size, narrowing of the size distribution width, and an improvement in sphericity when utilizing the donut-shaped laser beam. We performed time-resolved shadowgraph imaging of the laser-induced cavitation bubble, revealing a toroidal structure that overruns the ring-shaped ablation site, compared to the quasi-hemispherical bubble covering the ablation spot produced by the Gaussian beam.

Preferential enrichment and extraction of laser-synthesized nanoparticles in organic phases.

Pulsed laser ablation in liquids (LAL) is an established preparation method of nanoparticles and catalysts, which additionally allows to chemically modify the nanomaterials in situ via chemical reactions of the nanoparticles with the molecules or solutes of the liquid. Particularly when organic solvents are used as liquids, photothermally induced C-C cleavage, addition or dehydrogenation reactions of the solvents, as well as (carbon) functionalization of the nanoparticles have been observed, which ultimately should affect their lipophilicity and, hence, colloidal stability in apolar or polar solvents. Two-phase liquid systems and the possibility to transfer the surfactant-free nanoparticles from one liquid phase into another remain practically unaddressed in literature.

Inorganic Metal Nanoparticles in Reproductive Biology: Applications, Toxicities and Future Prospects.

The development of inorganic metal and metal oxide nanoparticles (MNPs) has attracted significant attention in diverse biomedical and biotechnological fields including bio-detection, drug delivery, imaging, and theranostics. An emerging field in this context is the use of MNPs for applications in reproductive biology. In this article, we offer a rational review of the development of MNPs employed in the field of reproductive biology by focusing on their interactions with highly delicate and specialized germ cells like spermatozoa, oocytes, and developing embryos.

Boosting Coercivity of 3D Printed Hard Magnets through Nano-Modification of the Powder Feedstock.

The demand for strong, compact permanent magnets essential for the energy transition drives innovation in magnet manufacturing. Additive manufacturing, particularly Powder Bed Fusion of metals using a laser beam (PBF-LB/M), offers potential for near-net-shaped Nd-Fe-B permanent magnets but often falls short compared to conventional methods. A less explored strategy to enhance these magnets is feedstock modification with nanoparticles.

Adsorption and Distribution of Triplex-Hybridizing Bioconjugated Gold Nanoclusters Inside Spermatozoa- A Study Using Confocal Microscopy and Fluorescence Lifetime Imaging.

The study of the interactions between biofunctionalized gold nanoclusters (Au NCs) and spermatozoa is highly relevant to evaluate the potential of Au NCs as imaging probes and transfection agents in reproductive biology. In this work, confocal laser scanning microscopy (CLSM) was used to investigate the distribution of Au NCs bioconjugated with peptide (nuclear localisation sequence, NLS) and oligonucleotide (locked nucleic acid, LNA) ligands in bovine spermatozoa. Fluorescence lifetime imaging (FLIM) was employed to detect changes in the NC's chemical environment.

Laser synthesis of nanoparticles in organic solvents - products, reactions, and perspectives.

Laser synthesis and processing of colloids (LSPC) is an established method for producing functional and durable nanomaterials and catalysts in virtually any liquid of choice. While the redox reactions during laser synthesis in water are fairly well understood, the corresponding reactions in organic liquids remain elusive, particularly because of the much greater complexity of carbon chemistry. To this end, this article first reviews the knowledge base of chemical reactions during LSPC and then deduces identifiable reaction pathways and mechanisms.

Platinum-Iridium Alloy Nanoparticle Coatings Produced by Electrophoretic Deposition Reduce Impedance in 3D Neural Electrodes.

Platinum-based neural electrodes, frequently alloyed with Ir or W, are routinely used to treat neurological disorders. However, their performance is impaired by an increase in impedance that compromises long-term implant functionality. Though there are multiple coating techniques available to address this issue, electrode, and base material often exhibit a compositional mismatch, which impairs mechanical stability and may lead to toxicological side effects.

Anti-biofilm properties of laser-synthesized, ultrapure silver-gold-alloy nanoparticles against Staphylococcus aureus.

Staphylococcus aureus biofilm-associated infections are a common complication in modern medicine. Due to inherent resilience of biofilms to antibiotics and the rising number of antibiotic-resistant bacterial strains, new treatment options are required. For this purpose, ultrapure, spherical silver-gold-alloy nanoparticles with homogenous elemental distribution were synthesized by laser ablation in liquids and analyzed for their antibacterial activity on different stages of S.

The multivariate interaction between Au and TiO colloids: the role of surface potential, concentration, and defects.

The established DLVO theory explains colloidal stability by the electrostatic repulsion between electrical double layers. While the routinely measured zeta potential can estimate the charges of double layers, it is only an average surface property which might deviate from the local environment. Moreover, other factors such as the ionic strength and the presence of defects should also be considered.

The Origin of the Intracellular Silver in Bacteria: A Comprehensive Study using Targeting Gold-Silver Alloy Nanoparticles.

The bactericidal effects of silver nanoparticles (Ag NPs) against infectious strains of multiresistant bacteria is a well-studied phenomenon, highly relevant for many researchers and clinicians battling bacterial infections. However, little is known about the uptake of the Ag NPs into the bacteria, the related uptake mechanisms, and how they are connected to antimicrobial activity. Even less information is available on AgAu alloy NPs uptake.

Surface Chemistry and Specific Surface Area Rule the Efficiency of Gold Nanoparticle Sensitizers in Proton Therapy.

Gold nanoparticles (AuNPs) are currently the most studied radiosensitizers in proton therapy (PT) applicable for the treatment of solid tumors, where they amplify production of reactive oxygen species (ROS). However, it is underexplored how this amplification is correlated with the AuNPs' surface chemistry. To clarify this issue, we fabricated ligand-free AuNPs of different mean diameters by laser ablation in liquids (LAL) and laser fragmentation in liquids (LFL) and irradiated them with clinically relevant proton fields by using water phantoms.

Impact of Chemical and Physical Properties of Organic Solvents on the Gas and Hydrogen Formation during Laser Synthesis of Gold Nanoparticles.

Laser ablation in liquids has been established as a scalable preparation method of nanoparticles for various applications. Particularly for materials prone to oxidation, it is established to suppress oxidation by using organic solvents as a liquid medium. While this often functionalizes the nanoparticles with a carbon shell, the related chemical processes that result from laser-induced decomposition reactions of the organic solvents remain uncertain.

Photomechanical Laser Fragmentation of IrO Microparticles for the Synthesis of Active and Redox-Sensitive Colloidal Nanoclusters.

Pulsed laser fragmentation of microparticles (MPs) in liquid is a synthesis method for producing high-purity nanoparticles (NPs) from virtually any material. Compared with laser ablation in liquids (LAL), the use of MPs enables a fully continuous, single-step synthesis of colloidal NPs. Although having been employed in several studies, neither the fragmentation mechanism nor the efficiency or scalability have been described.

Differentiating between Acidic and Basic Surface Hydroxyls on Metal Oxides by Fluoride Substitution: A Case Study on Blue TiO from Laser Defect Engineering.

Both oxygen vacancies and surface hydroxyls play a crucial role in catalysis. Yet, their relationship is not often explored. Herein, we prepare two series of TiO (rutile and P25) with increasing oxygen deficiency and Ti concentration by pulsed laser defect engineering in liquid (PUDEL), and selectively quantify the acidic and basic surface OH by fluoride substitution.

Impact of Sterilization on the Colloidal Stability of Ligand-Free Gold Nanoparticles for Biomedical Applications.

Sterilization is a major prerequisite for the utilization of nanoparticle colloids in biomedicine, a process well examined for particles derived from chemical synthesis although highly underexplored for electrostatically stabilized ligand-free gold nanoparticles (AuNPs). Hence, in this work, we comprehensively examined and compared the physicochemical characteristics of laser-generated ligand-free colloidal AuNPs exposed to steam sterilization and sterile filtration as a function of particle size and mass concentration and obtained physicochemical insight into particle growth processes. These particles exhibit long-term colloidal stability (up to 3 months) derived from electrostatic stabilization without using any ligands or surfactants.

Disproportional surface segregation in ligand-free gold-silver alloy solid solution nanoparticles, and its implication for catalysis and biomedicine.

Catalytic activity and toxicity of mixed-metal nanoparticles have been shown to correlate and are known to be dependent on surface composition. The surface chemistry of the fully inorganic, ligand-free silver-gold alloy nanoparticle molar fraction series, is highly interesting for applications in heterogeneous catalysis, which is determined by active surface sites which are also relevant for understanding their dissolution behavior in biomedically-relevant ion-release scenarios. However, such information has never been systematically obtained for colloidal nanoparticles without organic surface ligands and has to date, not been analyzed in a surface-normalized manner to exclude density effects.

Mechanical Stability of Nano-Coatings on Clinically Applicable Electrodes, Generated by Electrophoretic Deposition.

The mechanical stability of implant coatings is crucial for medical approval and transfer to clinical applications. Here, electrophoretic deposition (EPD) is a versatile coating technique, previously shown to cause significant post-surgery impedance reduction of brain stimulation platinum electrodes. However, the mechanical stability of the resulting coating has been rarely systematically investigated.

Assessing the NLRP3 Inflammasome Activating Potential of a Large Panel of Micro- and Nanoplastics in THP-1 Cells.

Due to the ubiquity of environmental micro- and nanoplastics (MNPs), inhalation and ingestion by humans is very likely, but human health effects remain largely unknown. The NLRP3 inflammasome is a key player of the innate immune system and is involved in responses towards foreign particulate matter and the development of chronic intestinal and respiratory inflammatory diseases. We established -proficient and -deficient THP-1 cells as an alternative in vitro screening tool to assess the potential of MNPs to activate the NLRP3 inflammasome.

Nanocomposite Concept for Electrochemical Preparation of Pt-Au Alloy Nanoparticles for Formic Acid Oxidation.

Herein, we report a straightforward approach for the preparation of Pt-Au alloy nanoparticles from Pt + Au/C nanocomposites using monometallic colloidal nanoparticles as starting blocks. Four different compositions with fixed Pt content and varying Pt to Au mass ratios from 1:1 up to 1:7 were prepared as formic acid oxidation reaction (FAOR) catalysts. The study was carried out in a gas diffusion electrode (GDE) setup.