Mechanistic Observation of Interactions between Macrophages and Inorganic Particles with Different Densities.

Many different types of inorganic materials are processed into nano/microparticles for medical utilization. The impact of selected key characteristics of these particles, including size, shape, and surface chemistries, on biological systems, is frequently studied in clinical contexts. However, one of the most important basic characteristics of these particles, their density, is yet to be investigated. When the particles are designed for drug delivery, highly mobile macrophages are the major participants in cellular levels that process them in vivo. As such, it is essential to understand the impact of particles' densities on the mobility of macrophages. Here, inorganic particles with different densities are applied, and their interactions with macrophages studied. A set of these particles are incubated with the macrophages and the outcomes are explored by optical microscopy. This microscopic view provides the understanding of the mechanistic interactions between particles of different densities and macrophages to conclude that the particles' density can affect the migratory behaviors of macrophages: the higher the density of particles engulfed inside the macrophages, the less mobile the macrophages become. This work is a strong reminder that the density of particles cannot be neglected when they are designed to be utilized in biological applications.

Low-temperature liquid platinum catalyst.

Insights into metal-matrix interactions in atomically dispersed catalytic systems are necessary to exploit the true catalytic activity of isolated metal atoms. Distinct from catalytic atoms spatially separated but immobile in a solid matrix, here we demonstrate that a trace amount of platinum naturally dissolved in liquid gallium can drive a range of catalytic reactions with enhanced kinetics at low temperature (318 to 343 K). Molecular simulations provide evidence that the platinum atoms remain in a liquid state in the gallium matrix without atomic segregation and activate the surrounding gallium atoms for catalysis. When used for electrochemical methanol oxidation, the surface platinum atoms in the gallium-platinum system exhibit an activity of [Formula: see text] three orders of magnitude higher than existing solid platinum catalysts. Such a liquid catalyst system, with a dynamic interface, sets a foundation for future exploration of high-throughput catalysis.

Insights into the Interfacial Contact and Charge Transport of Gas-Sensing Liquid Metal Marbles.

Understanding the interfacial contacts between liquid metals and substrate materials is becoming increasingly important for the fast-rising liquid metal-enabled technologies. However, for such technologies, probing the contact behavior and interfacial charge transport has remained challenging due to the deformable nature of liquid metals and the presence of the surface oxide layer. Here, we encapsulate eutectic gallium indium (EGaIn) micro-/nanodroplets with tungsten trioxide (WO3) nanoparticles to form a WO3/EGaIn liquid metal marble network, in which the interfacial contact of the intrinsically semiconducting WO3 governs the charge transport. We investigate the interfacial structures and charge transport characteristics under different contact conditions and various gaseous environments. The results suggest that establishing a WO3/EGaIn heterostructure leads to near-ohmic contact behaviors and also the emergence of localized surface plasmon resonance. Density functional theory calculations of the WO3/EGaIn interface support the experiments by revealing atomistic attractions between EGaIn alloy and the O atoms from WO3, resulting in a Fermi level shift. We also show that the efficient interfacial charge transport of the liquid metal marble network results in an enhanced gas-sensing response. This work paves the way for the possibility of studying other liquid metal/semiconductor contacts for applications in soft electronics and optics.

Two-Dimensional Ultra-Thin Nanosheets with Extraordinarily High Drug Loading and Long Blood Circulation for Cancer Therapy.

Nanoparticle drug delivery is largely restricted by the low drug loading capacity of nanoparticle carriers. To address this critical challenge and maximize the potential of nanoparticle drug delivery, a 2D ultra-thin layered double hydroxide (LDH) nanosheet with exceptionally high drug loading, excellent colloidal stability, and prolonged blood circulation for cancer treatment is constructed. The nanosheet is synthesized via a biocompatible polymer-assisted bottom-up method and exhibits an ultra-thin 2D sheet-like structure that enables a considerable amount of cargo anchoring sites available for drug loading, leading to an extraordinary 734% (doxorubicin/nanoparticle mass ratio) drug loading capacity. Doxorubicin delivered by the nanosheet remains stable on the nanosheet carrier under the physiological pH condition, while showing sustained release in the tumor microenvironment and the intracellular environment, thus demonstrating on-demand drug release as a result of pH-responsive biodegradation of nanosheets. Using in vitro and in vivo 4T1 breast cancer models, the nanosheet-based ultra-high drug-loading system demonstrates even enhanced therapeutic performance compared to the multilayered LDH-based high drug-loading system, in terms of increased cellular uptake efficiency, prolonged blood circulation, superior therapeutic effect, and reduced systemic toxicity.

Liquid-Metal-Enabled Mechanical-Energy-Induced CO2 Conversion.

A green carbon capture and conversion technology offering scalability and economic viability for mitigating CO2 emissions is reported. The technology uses suspensions of gallium liquid metal to reduce CO2 into carbonaceous solid products and O2 at near room temperature. The nonpolar nature of the liquid gallium interface allows the solid products to instantaneously exfoliate, hence keeping active sites accessible. The solid co-contributor of silver-gallium rods ensures a cyclic sustainable process. The overall process relies on mechanical energy as the input, which drives nano-dimensional triboelectrochemical reactions. When a gallium/silver fluoride mix at 7:1 mass ratio is employed to create the reaction material, 92% efficiency is obtained at a remarkably low input energy of 230 kWh (excluding the energy used for dissolving CO2 ) for the capture and conversion of a tonne of CO2 . This green technology presents an economical solution for CO2 emissions.

Exploring Interfacial Graphene Oxide Reduction by Liquid Metals: Application in Selective Biosensing.

Liquid metals (LMs) are electronic liquid with enigmatic interfacial chemistry and physics. These features make them promising materials for driving chemical reactions on their surfaces for designing nanoarchitectonic systems. Herein, we showed the interfacial interaction between eutectic gallium-indium (EGaIn) liquid metal and graphene oxide (GO) for the reduction of both substrate-based and free-standing GO. NanoIR surface mapping indicated the successful removal of carbonyl groups. Based on the gained knowledge, a composite consisting of assembled reduced GO sheets on LM microdroplets (LM-rGO) was developed. The LM enforced Ga3+ coordination within the rGO assembly found to modify the electrochemical interface for selective dopamine sensing by separating the peaks of interfering biologicals. Subsequently, paper-based electrodes were developed and modified with the LM-rGO that presented the compatibility of the assembly with low-cost commercial technologies. The observed interfacial interaction, imparted by LM's interfaces, and electrochemical performance observed for LM-rGO will lead to effective functional materials and electrode modifiers.

Polydopamine Shell as a Ga3+ Reservoir for Triggering Gallium-Indium Phase Separation in Eutectic Gallium-Indium Nanoalloys.

Low melting point eutectic systems, such as the eutectic gallium-indium (EGaIn) alloy, offer great potential in the domain of nanometallurgy; however, many of their interfacial behaviors remain to be explored. Here, a compositional change of EGaIn nanoalloys triggered by polydopamine (PDA) coating is demonstrated. Incorporating PDA on the surface of EGaIn nanoalloys renders core-shell nanostructures that accompany Ga-In phase separation within the nanoalloys. The PDA shell keeps depleting the Ga3+ from the EGaIn nanoalloys when the synthesis proceeds, leading to a Ga3+-coordinated PDA coating and a smaller nanoalloy. During this process, the eutectic nanoalloys turn into non-eutectic systems that ultimately result in the solidification of In when Ga is fully depleted. The reaction of Ga3+-coordinated PDA-coated nanoalloys with nitrogen dioxide gas is presented as an example for demonstrating the functionality of such hybrid composites. The concept of phase-separating systems, with polymeric reservoirs, may lead to tailored materials and can be explored on a variety of post-transition metals.

A dual enzyme-mimicking radical generator for enhanced photodynamic therapy via series-parallel catalysis.

Tumor hypoxia hampers the therapeutic efficacy of photodynamic therapy (PDT) by hardly supplying sufficient oxygen to produce cytotoxic compounds. Herein a dual enzyme-mimicking radical generator has been developed for the in situ generation of oxygen and abundant radical oxygen species to enhance PDT efficacy under photoacoustic imaging guidance. A manganese-incorporating and photosensitizer-loaded metal organic framework exhibited both catalase-like and peroxidase-like catalytic activities specifically at the tumor microenvironment, leading to simultaneous series catalysis and parallel catalysis pathways. As a result, the MOF-based radical generator nanoparticles can not only supply oxygen for PDT to produce singlet oxygen, but also generate hydroxyl radicals, thus further enhancing the anti-cancer effect of PDT. In vitro and in vivo evaluation of the radical generator nanoparticles demonstrated the relieved tumor hypoxia microenvironment, remarkably increased level of reactive oxygen species, and significantly improved anti-cancer effect with desirable PA imaging capacity. This work presents a "series-parallel catalysis" strategy enabled by a MOF nanozyme to enhance PDT efficiency and provides new insights into a highly efficient and low-toxic anti-cancer approach.

Chemotaxis-Driven 2D Nanosheet for Directional Drug Delivery toward the Tumor Microenvironment.

Micro/nanoscaled motor particles represent a group of intelligent materials that can precisely and rapidly respond to biological microenvironments and improve therapeutic outcomes. In order to maximize biomedical application potentials, developing a nanoscaled motor particle that is able to move autonomously toward a biological target is highly desired but still remains a critical challenge. Herein, a 2D nanosheet-based catalytic nanomotor with chemotaxis behavior is developed for enhanced drug delivery toward the tumor microenvironment. The nanomotors are constructed via a facile one-pot method and exhibit ultrathin monolayer nanosheet morphology. The 2D structure of nanomotors allows high catalytic activity, leading to responsive, sustained, and relatively long distance movement. Importantly, this nanomotor demonstrates directional motion toward the high gradient of H2 O2 fuel, exhibiting excellent chemotactic properties. After loading an anticancer drug doxorubicin, the nanomotor shows effective inhibition on cancer cell growth in simulated tumor microenvironments. The practical drug delivery application is further strengthened by the intracellular acidity-triggered biodegradability of the nanomotor after accomplishing the directional drug delivery function. This proof-of-concept work highlights the efficient catalytic activity, tumor microenvironment-guided chemotactic movement, excellent cellular performance of the 2D nanomotor, and opens an avenue for biomedical applications such as controlled and smart drug delivery.

Metal-organic frameworks as protective matrices for peptide therapeutics.

An increasing number of peptide drugs have been identified or synthesized in recent decades, and they have played an important role in disease treatments and scientific research. Peptide drugs have become emerging candidates in the pharmaceutical market, despite some inherent disadvantages that have hindered their further development (i.e., they are chemically and physically unstable). Considering that cold-storage conditions are not easily accessible, particularly in developing countries, it remains a significant challenge to find a facile way to enhance the stability of peptide drugs. In this study, we developed an efficient and facile strategy to provide peptide drugs a strong protection against harsh conditions by biomineralizing metal-organic frameworks (MOFs) around the peptide drugs. Our results showed that the peptides released from MOFs retained their structures and full biological activities after being exposed to high temperatures, repeated freeze-thaw cycles and enzyme degradation. This study provides an alternative method for the storage of biopharmaceuticals and for enhancing their stability under ambient conditions.

Improvement on Fluorine Migration from SF6 to SiF4 by an Efficient Mediator of Fe2O3/Cr2O3 Composites.

An economic and facile method was urgently required for the degradation of SF6 to replace the high-energy excitation treatment. Both theoretical calculations and experimental observations were conducted to reveal the synergy of Cr/Fe/Si composites on a new technique of SF6 degradation through reacting silicon dioxide. Density functional theory (DFT) calculations show that strong adsorption of SF6 on Cr2O3, and then the fast F/O exchange between CrF3 and Fe2O3 (energy barrier was 1.45 eV) as well as FeF3 and SiO2 (energy barrier was 1.69 eV) enhanced mediated efficiency from SF6 to SiF4. The fluorine (F) migration between solid interfaces in Cr2O3&Fe2O3@SBA15 was responsible for efficient SF6 removal. The F migration route was composed of SF6 to CrF3, CrF3 to FeF3, and FeF3 to SiF4 with the lowest thermodynamic driving. Enhanced specific accumulative converted amount (SACA) of SF6 on Cr2O3&Fe2O3@SBA15 was achieved and the highest SACA was 13.98 mmol/g within 7 h, significantly higher than that on Fe2O3@SBA15 (5.74 mmol/g) and Cr2O3@SBA15 (2.71 mmol/g). Moreover, X-ray diffractometry and X-ray photoelectron spectroscopy were performed to support DFT calculations, including ion intensities detected using mass spectroscopy and composition analysis of the mediator during the reaction. Therefore, our work put forward a novel approach for economic and efficient SF6 decomposition through reacting with silicon dioxide under the mediation of Cr2O3&Fe2O3. This method was also potentially used in effective degradation of refractory non-metal halides.

Manganese-Based Magnetic Layered Double Hydroxide Nanoparticle: A pH-Sensitive and Concurrently Enhanced T1/T2-Weighted Dual-Mode Magnetic Resonance Imaging Contrast Agent.

The interference effect and lack of selectivity are the bottlenecks for dual-mode magnetic resonance imaging (MRI) contrast agent development. To address these challenges and overcome the single mode imaging contrast limitations, a novel MgMnAl-layered double hydroxide@iron oxide nanoparticle (MgMnAl-LDH@IO NP) has been successfully synthesized as a concurrently enhanced dual-mode contrast agent for MRI of tumor tissues with sensitive pH response and high efficacy. The attachment of iron oxide nanoparticles on the surface of MgMnAl-LDH NPs led to the increased local magnetic field intensity, inducing the concurrent enhancement of both T1 and T2 relaxivity. The in vitro MRI demonstrated that the MgMnAl-LDH@IO NP could act as a pH-sensitive contrast agent for both T1- and T2-weighted MR imaging (r1, 5.67 mM-1 s-1 under pH 5.0 and 1.98 mM-1 s-1 under pH 7.4; r2, 369.12 mM-1 s-1 under pH 5.0 and 225.29 mM-1 s-1 under pH 7.4). The biocompatibility of the dual-mode contrast agent was revealed by the cytotoxicity test on fibroblast cells. Further in vivo dual-mode MR imaging exhibited that the MgMnAl-LDH@IO NP showed clear T1- and T2-weighted MR imaging of tumor tissues in breast-tumor-bearing mice. The facile synthetic method, desirable biocompatibility, sensitive stimuli response, and concurrently enhanced T1/T2 MRI signals both in vitro and in vivo encourage the great potential biomedical and clinical applications of MgMnAl-LDH@IO NP in MR imaging with improved accuracy.

Biodegradable 2D Fe-Al Hydroxide for Nanocatalytic Tumor-Dynamic Therapy with Tumor Specificity.

Therapeutic nanocatalysis has emerged as an intriguing strategy for efficient cancer-specific therapy, but the traditional inorganic nanocatalysts suffer from low catalytic efficiency and difficulty in biodegradation, hindering their further clinical translation. Herein, a tumor microenvironment-triggered, biodegradable and biocompatible nanocatalyst employing 2D hydroxide nanosheet is presented, and is shown to have high catalytic capacity to efficiently produce abundant hydroxyl radicals under the tumor microenvironment and consequently kill tumor cells selectively. A polyethylene glycol (PEG)-conjugated Fe2+-containing hydroxide nanosheet is successfully constructed via a facile but efficient bottom-up approach that concurrently realizes nanosheet synthesis and PEGylation. Importantly, the nanosheets are featured with high catalytic activity to disproportionate H2O2 in tumors, and consequently generate abundant hydroxyl radicals at a high reaction rate under tumorous acidic condition; the highly toxic hydroxyl radicals, as a result, cause the death of tumor cells in vitro and suppress the tumor growth in vivo without the use of any supplementary toxic agent, only with the biocompatible nanocatalysts. Meanwhile, the desirable biodegradation and biocompatibility of the hydroxide nanosheet render a high degree of safety to the organism. Therefore, this work provides the first paradigm of biodegradable 2D nanocatalytic platform with concurrently high catalytic-therapeutic performance and biosafety for efficient tumor-specific treatment.

Enhanced colloidal stability and protein resistance of layered double hydroxide nanoparticles with phosphonic acid-terminated PEG coating for drug delivery.

Conjugating nanoparticles with polyethylene glycol (PEG) is a useful strategy to improve the colloidal and biological stability of nanoparticles. However, studies on PEGylation of two-dimensional layered double hydroxide (LDH) nanoparticles are very limited. The present work reported two functionalization approaches to synthesize PEG-conjugated LDH nanoparticles by introducing phosphonic acid terminated PEG before and after LDH aging. The successful PEGylation was confirmed and suggested to be via electrostatic interaction and a ligand exchange process. Different functionalization approaches resulted in different binding types of PEG on/in LDH nanoparticles. The PEG coating maintained the dispersity of LDH nanoparticles in water and saline with the feeding mass ratio of 1:1. Further colloidal stability tests of PEGylated LDHs revealed that the PEGylated LDH dispersity was affected by the feeding mass ratio of PEG/LDH, the molar weight of PEG and anions intercalated in the LDHs. In a test to determine the extent of non-specific protein adsorption, the PEGylation was effective at resisting non-specific bovine serum albumin adsorption on LDH nanoparticles with both functionalization methods investigated. Moreover, PEGylated LDH nanoparticles had no effect on cell viability up to 500 µg/mL, and demonstrated enhanced cellular uptake in a SK-MEL-28 cell culture. The results in this work indicate that conjugating phosphonic acid-terminated PEG on LDH nanoparticles is a promising strategy to improve the colloidal and biological stability of LDHs for biomedical applications.

Layered double hydroxide nanoparticles: Impact on vascular cells, blood cells and the complement system.

The mounting interest in layered double hydroxide (LDH) nanoparticles as drug carriers and bio-imaging contrast agents makes biosafety evaluation of LDH essential. Considering the important role of blood circulation in bio-distribution of nanoparticles, the present work evaluated the impact of MgAl-LDHs on key components of the circulatory system, including vascular cells (vascular smooth muscle cells (SMCs) and endothelial cells (HUVECs)), red blood cells (RBCs), and complement activation. The results showed that LDH had no effects on SMCs and HUVECs at concentrations up to 500 and 10 µg/mL respectively, in terms of cell proliferation and viability. LDH (10 µg/mL) did not change either the migration distance or the number of migrating SMCs in culture. Moreover, LDH (400 µg/mL) had a negligible effect on RBCs' lysis, and there was no significant increase in levels of complement activation product, C5a, in the presence of LDH (20 or 200 µg/mL). The low toxicity for vascular cells and blood cells combined with low immunogenicity sheds a light on the biosafety of LDH nanoparticles, and encourages further studies into their biomedical applications.

Electroplating sludge derived zinc-ferrite catalyst for the efficient photo-Fenton degradation of dye.

A zinc-dominant ferrite catalyst for efficient degradation of organic dye was prepared by the calcination of electroplating sludge (ES). Characterizations indicated that zinc ferrite (ZnFe2O4) coexisted with Fe2O3 structure was the predominant phase in the calcined electroplating sludge (CES). CES displayed a high decolorization ratio (88.3%) of methylene blue (MB) in the presence of H2O2 combined with UV irradiation. The high efficiency could be ascribed to the photocatalytic process induced by ZnFe2O4 and the photo-Fenton dye degradation by ferrous content, and a small amount of Al and Mg in the sludge might also contribute to the catalysis. Moreover, the degradation capability of dye by CES was supported by the synthetic ZnFe2O4 with different Zn to Fe molar ratio (n(Zn): n(Fe)), as 84.81%-86.83% of dye was removed with n(Zn): n(Fe) ranged from 1:0.5 to 1:3. All synthetic ferrite samples in the simulation achieved adjacent equilibrium decolorization ratio, the flexible proportioning of divalent metal ions (M2+) to trivalent metal ions (M3+) applied in the synthesis indicated that the catalyst has a high availability. Therefore, an efficacious catalyst for the degradation of dye can potentially be derived from heavy metal-containing ES, it's a novel approach for the reutilization of ES.

Enrichment of heavy metals in fine particles of municipal solid waste incinerator (MSWI) fly ash and associated health risk.

During the pretreatment and recycling processes, the re-suspended dust from municipal solid waste incinerator (MSWI) fly ash might pose a significant health risk to onsite workers due to its toxic heavy metal content. In this work, the morphological and mineralogical characteristics of fly ash in different particle sizes are presented. The concentrations of seven trace elements (Zn, Pb, Cu, Cd, Cr, Fe and Mn) in these samples were determined. The results show that volatile metals, such as Zn, Pb, Cu and Cd, were easily concentrated in the fine particles, especially in Dp2.5-1 and Dp1, with soluble and exchangeable substances as the main chemical species. The health risk assessment illustrated that the cumulative hazard indexes for non-carcinogenic metals in Dp10-5, Dp5-2.5, Dp2.5-1, and Dp1 were 1.69, 1.41, 1.78 and 2.64, respectively, which were higher than the acceptable threshold values (1.0). The cumulative carcinogenic risk was also higher than the threshold value (10(-6)). For the onsite workers, the relatively apparent non-carcinogenic and carcinogenic effects were from Pb and Cr, respectively. The above findings suggest that fine-grained fly ash contained a considerable amount of heavy metals and exhibited a great health risk.

Reuse of hazardous calcium fluoride sludge from the integrated circuit industry.

The Chinese integrated circuit industry has been transformed from a small state-owned sector into a global competitor, but chip manufacturing produces large amounts of calcium fluoride sludges (CFS). In China, landfill is a current option for treating CFS. In order to solve the problem of unavailable landfill sites and prevent fluorine from dissolved CFS polluting water sources, CFS was tested as a component for a ceramic product made with sodium borate, sodium phosphate and waste alumina using a low-temperature sintering technology, and the effects of various factors on characteristics of the ceramic were investigated to optimize the process. The best sintering temperature was controlled at 700°C, and the optimal raw material ratio of the ceramic was 11% sodium borate, 54% sodium phosphate, 30% CFS and 5% waste alumina. The CFS ceramic was characterized by a morphological structure and X-ray diffraction. The results indicated that CFS was transformed into Na2Ca(PO4)F as an inert and a main crystalline phase in the ceramic, which was enclosed by the borophosphate glass. Toxicity characteristic leaching procedure, corrosion resistance and compressive strength tests verified CFS ceramic as a qualified construction ceramic material, and the fluorine from CFS was solidified in the inert crystalline phase, which would not be released to cause secondary pollution. This novel technology not only avoids the CFS hydrolyzing reaction forming harmful hydrofluoric acid gas at 800°C and above, but also produces high-performance ceramics as a construction material, in accordance with the concept of sustainable development.