Anthropogenic activities generate industrial wastewater, posing the greatest threat to the environment and requiring cleanup to mitigate environmental impacts and human health risks. Because of their remarkable characteristics, Fe₃O₄-based magnetic nanoparticles (MNPs) have recently gained popularity as powerful tools for wastewater treatment. To alleviate the qualitative strain on water supplies, MNPs have found newer applications owing to their inherent characteristics. Herein, the physical, chemical, and biological/green approaches for the synthesis and assembly of MNPs are deliberated, with biologically derived options found to be environmentally benign and sustainable in the long term. The efficacy of MNPs in the elimination or recovery of various wastewater contaminants, such as heavy metals, inorganic pollutants, dyes, biological pollutants, and microalgae, is presented. Moreover, the advantages and disadvantages of MNPs in their usage for wastewater treatment, the removal mechanism via coagulation, and the manufacture of MNPs are appraised in detail. Finally, the potential of Fe₃O₄-based MNPs for deployment in environmental cleanup and their future applications are addressed.

Nowadays, the interest in the design of particles that combine therapy and diagnosis simultaneously to obtain a theranostic material has increased. One of the most used materials for MRI diagnosis is iron oxide, where clusters of superparamagnetic iron oxide (SPIONs) are noteworthy candidates. These particles are of high interest due to their broad range of applications, such as contrast agents, use in magnetic separation processes, and in hyperthermia therapy, among others. One of the major problems with their use is maintaining superparamagnetism while having the highest magnetization-to-particle ratio. In this work, microwave-assisted synthesis of clusters formed by SPIONs has been investigated. This synthesis strategy allows for significant reduction in the time and energy required to obtain SPION clusters. Also, the magnetization-to-particle ratio has been increased in comparison with single SPIONs. Subsequently, the clusters are coated with amorphous silica using the Stöber method, followed by mesoporous (MS) silica using the atrane method, which offers high and conformal coating homogeneity over the clusters. Surfactant extraction was done using a simple mixture of water, ethanol, and sodium chloride – avoiding the use of other organic solvents. Finally, as a proof of concept, the loading and release of a model molecule were studied to confirm that the SPION-NCs@MS presented in this work have great potential as theranostic agents.

Nanoparticle (NP) uptake by macrophages and their accumulation in undesired organs such as the liver and spleen constitute a major barrier to the effective delivery of NPs to targeted tissues for bioimaging and therapeutics. Surface functionalization with polyethylene glycol (PEG) has been demonstrated to be a promising strategy to limit NP sequestration, although its longitudinal stability under physiological conditions and impact on the NP biodistribution have not been investigated with an in vivo quantitative approach. X-ray fluorescence (XRF) imaging has been employed to noninvasively map the in vivo biodistribution of purposely designed molybdenum-based contrast agents, leading to submillimeter resolution, elemental specificity, and high penetration depth. In the present work, we design a stepwise layering approach for NP synthesis to investigate the role of chemisorbed and physisorbed PEG on silica-coated molybdenum-based contrast agents in affecting their in vivo biodistribution, using whole-body XRF imaging. Comparative quantitative in vivo studies indicated that physisorbed PEG (1.5 kDa) did not substantially affect the biodistribution, while the chemisorption route with mPEG-Si (6–9 PEG units) led to significant macroscopic variations in the biodistribution, leading to a reduction in NP uptake by the liver. Furthermore, the results highlighted the major role of the spleen in compensating for the limited sequestration by the liver, microscopically validated with a multiscale imaging approach with fluorophore doping of the silica shell. These findings demonstrated the promising role of XRF imaging for the rapid assessment of surface-functionalized contrast agents with whole-body in vivo quantitative pharmacokinetic studies, establishing the groundwork for developing strategies to identify and bypass undesired NP uptake.

This study explores the development of a water-based hybrid thermoelectric (TE) material composed of Sb2Te3 nanoparticles (NPs) and polyethylene oxide (PEO). Sb2Te3 NPs were synthesized via the microwave-assisted colloidal route, where X-ray diffraction confirmed the purity and quality of the Sb2Te3 NPs. Key properties, including the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF), and long-term stability, were studied. X-ray photoelectron spectroscopy (XPS) analysis revealed that exposure to water and oxygen leads to NP oxidation, which can be partially mitigated by hydrochloric acid (HCl) treatment, though this does not halt ongoing oxidation. Scanning electron microscopy (SEM) images displayed a percolation network of NPs within the PEO matrix. While the initial σ was high, a decline occurred over eight weeks, resulting in similar conductivity among all samples. The effect of surface treatments, such as 1,6-hexanedithiol (HDT), was demonstrated to enhance long-term stability. The results highlight both the challenges and potential of Sb2Te3/PEO hybrids for TE applications, especially regarding oxidation and durability, and underscore the need for improved synthesis and processing techniques to optimize their performance. This study provides valuable insights for the design of next-generation hybrid TE materials and emphasizes the importance of surface chemistry control in polymer–inorganic nanocomposites.

A nanocomposite of metal nanoclusters/OSTE is fabricated through off-stoichiometric thiol-ene polymerization, incorporating adamantanethiol-protected electrum nanoclusters Au_23-xAg_x(SAdm)₁₅ (where x = 7.44) along with the OSTE monomer. During the photopolymerization, there is a transforfation of the precursor nanoclusters and the nanocomposite achieves a maximum photoluminescence quantum yield of ≈73% at 740 nm and 60% at the 850 nm emission peak. The photophysical characteristics of nanocomposite AuAgNCs@OSTE are examined at both ambient and low temperatures, revealing an improved radiative recombination mechanism through the interactions with polymer radicals. This high photoluminescence quantum yield near-infrared-emitting AuAgNCs@OSTE material, distinguished by a larger Stokes shift, is utilized to fabricate luminescent solar concentrators measuring 5 × 5 × 0.13 cm³. Experimental measurements are conducted to determine the absorption coefficient, reabsorption coefficient, absorption cross-section, and volume concentration of the device. Additionally, theoretical evaluations of waveguiding efficiency and power conversion efficiency are performed and compared with quantum dot-based alternatives. The findings indicate that the metal NCs@OSTE nanocomposite has the potential to function as a highly efficient, heavy-metal-free nanophosphor, demonstrating superior overall performance for semi-transparent luminescent solar concentrator devices and being suitable for a broad range of light conversion applications in the NIR spectrum.

Background: Systemically administered nanoparticles (NPs) designed for biomedical applications are retained in liver and spleen where they become rapidly phagocyted by tissue macrophages leading to inflammation. Methods: To gain insight into the NP-immune cell interaction in liver spleen and lungs, we followed the distribution of molybdenum nanoparticles (MoNPs) in vivo by X-Ray Fluorescence Imaging (XRF) and examined the NP-macrophage interaction and physiological response in these organs. Results: XRF imaging showed that intravenously administered MoNPs transiently accumulate in lungs, liver, and spleen. This leads to increments in the number of Kupffer cells (KC), natural killer (NK) cells, oxidative stress, and inflammation. Macrophage phenotype switched from pro- to an anti-inflammatory. In parallel genes with immunoregulatory and cytoprotective functions were expressed to maintain homeostasis. Nanoparticle uptake in spleen was operated by CD169/Siglec1 splenic macrophages indicating initiation of a secondary immune response. Silica coating reduced nanoparticle toxicity. Conclusion: The innate immunoresponse to NP uptake in liver and spleen is similar to viral or bacterial infections in these organs. A possible secondary immunoresponse to NPs can be primed in spleen aided by CD169/Siglec1 splenic macrophages. Silica coating of metal NPs tunes down this response.

Nanodiamonds (NDs) display several attractive features rendering them useful for medical applications such as drug delivery. However, the interactions between NDs and the immune system remain poorly understood. Here, we investigated amino-, carboxyl-, and poly(ethylene glycol) (PEG)-terminated NDs with respect to primary human immune cells. We applied cytometry by time-of-flight (CyToF) to assess the impact on peripheral blood mononuclear cells at the single-cell level, and observed an expansion of plasmacytoid dendritic cells (pDCs) which are critically involved in antiviral responses. Subsequent experiments demonstrated that the NDs were actively internalized, leading to a vigorous type I interferon response involving endosomal Toll-like receptors. ND-NH2 and ND-COOH were more potent than ND-PEG, as evidenced by using TLR reporter cell lines. Computational studies demonstrated that NDs interacted with the ligand-binding domains of TLR7 and TLR9 with high affinity though this was less pronounced for ND-PEG. NDs with varying surface functionalities were also readily taken up by macrophages. To gain further insight, we performed RNA sequencing of a monocyte-like cell line exposed to NDs, and found that the phagosome maturation pathway was significantly affected. Indeed, evidence for lysosomal hyperacidification was obtained in dendritic cells and macrophages exposed to NDs. Moreover, using a reporter cell line, NDs were found to impinge on autophagic flux. However, NDs did not affect viability of any of the cell types studied. This study has shown that NDs subvert dendritic cells leading to an antiviral-like immune response. This has implications not only for drug delivery but also for anticancer vaccines using NDs.

Bismuth telluride-Bi2Te3 is the most promising material for harvesting thermal energy near room temperature. There are numerous works on Bi2Te3 reporting significantly different transport properties, with no clear connection to the synthetic routes used and the resultant surface chemistry of the synthesized materials. It is of utmost importance to characterize the constituent particles’ surface and interfaces to get a better understanding of their influence on the transport properties, that will significantly improve the material design starting from the synthesis step. Electrophoretic deposition (EPD) is a promising technique, enabling the formation of thick films using colloidally stabilized suspensions of pre-made nanoparticles, which can enable the study of the effect of surface chemistry, in connection to the synthetic route, on the material's transport properties. In order to explore the differences in surface chemistry and the resultant transport properties in relation to the synthetic scheme used, here we report on Bi2Te3 synthesised through two wet-chemical routes in water (Hydro-) and oil (Thermo-) as the solvents. XRD analysis showed a high phase purity of the synthesized materials. SEM analysis revealed hexagonal platelet morphology of the synthesized materials, which were then used to fabricate EPD films. Characterization of the EPD films reveal significant differences between the Hydro- and Thermo-Bi2Te3 samples, leading to about 8 times better electrical conductivity values in the Thermo-Bi2Te3. XPS analysis revealed a higher metal oxides content in the Hydro-Bi2Te3 sample, contributing to the formation of a resistive layer, thus lowering the electrical conductivity. Arrhenius plots of electrical conductivity vs inverse temperature was used for the estimation of the activation energy for conduction, revealing a higher activation energy need for the Hydro-Bi2Te3 film, in agreement with the resistive barrier oxide content. Both the samples exhibited negative Seebeck coefficient (S) in the order of 160–170 mV/K. The small difference in S of Hydro- and Themo-Bi2Te3 films was explained by the effective medium theory, revealing that the magnitude of S is linearly correlated with the surface oxide content. Based on the findings, TE materials synthesized through thermolysis route is recommended for further studies using soft treatment/processing of pre-made TE materials. EPD platform presented here is shown to clearly expose the differences in the electronic transport in connection to nanoparticle surface chemistry, proving a promising methodology for the evaluation of morphology, size and surface chemistry dependence of electronic transport for a wide range of materials.

Due to organ donor shortages, long transplant waitlists, and the complications/limitations associated with auto and allotransplantation, biomaterials and tissue-engineered models are gaining attention as feasible alternatives for replacing and reconstructing damaged organs and tissues. Among various tissue engineering applications, bone tissue engineering has become a promising strategy to replace or repair damaged bone. We aimed to provide an overview of bioactive ceramic scaffolds in bone tissue engineering, focusing on angiogenesis and the effect of different biofunctionalization strategies. Different routes to angiogenesis, including chemical induction through signaling molecules immobilized covalently or non-covalently, in situ secretion of angiogenic growth factors, and the degradation of inorganic scaffolds, are described. Physical induction mechanisms are also discussed, followed by a review of methods for fabricating bioactive ceramic scaffolds via microfabrication methods, such as photolithography and 3D printing. Finally, the strengths and weaknesses of the commonly used methodologies and future directions are discussed.

Nanomaterials adorned on graphene comprise an essential component of a wide range of devices wherein graphene-based copper oxide nanocomposites have garnered significant attention in recent years. Copper oxides (CuO and Cu2O) are semiconductors with distinctive optical, electrical, and magnetic properties. Their earth abundance, low cost, narrow bandgap, high absorption coefficient, and low toxicity of copper oxides are just a few key advantages. CuO is superior to Cu2O in optical switching applications because of its narrower bandgap. Therefore, integrating graphene with copper oxides renders the ensuing nanocomposites much more valuable for various applications. Not surprisingly, a wide range of promising synthesis and processing techniques have been considered, focusing on multiple appliances such as sensors, energy storage, harvesting, and electrocatalysis. Herein, the most recent synthesis techniques and applications of doped, undoped, and hierarchical structures of CuO/Cu2O-graphene-based nanocomposites are deliberated, including the potential future usages.