Biological systems can convert ionic gold precursors into nanoparticles (NPs) via redox-driven mineralization, yet the pathways and outcomes remain poorly understood. To address this, we investigated gold nanoparticle (Au NP) spontaneous formation from tetrachloroauric acid (HAuCl4) and sodium aurothiomalate (NaAuS) in mammalian cells and a complete cell culture medium. HAuCl4 underwent rapid multielectron reduction, producing abundant small intracellular NPs that, at higher concentrations, coalesced into compact clusters and compromised cell viability. In contrast, NaAuS followed slower one-electron reduction, was tolerated at higher concentrations, and yielded fewer but larger assemblies, including fibrous superstructures composed of crystalline Au domains. Extracellular mineralization generated morphologies distinct from those observed intracellularly, indicating that intracellular NPs result from cytoplasmic reduction rather than the uptake of extracellular products. Perturbations of the redox balance suppressed intracellular nucleation and promoted Au reduction in the extracellular milieu. Analysis of the NP size distributions provided mechanistic fingerprints: HAuCl4 produced narrow Gaussian-like profiles under synchronized nucleation, whereas NaAuS consistently generated broader log-normal distributions reflecting asynchronous growth. These findings demonstrate that the precursor and cellular redox state can be adjusted to control NP localization and morphology. Overall, this work links precursor chemistry and redox biology to NP architecture and highlights opportunities for biologically guided nanoparticle synthesis in imaging and therapeutic applications.

Cavities at protein-protein interaction interfaces are considered "undruggable" because their shallow or large geometries hinder stable binding by small molecules. Overcoming this limitation is essential for developing new therapies. Cerium oxide nanoparticles (CeO2NPs) of a suitable size can occupy the 5 nm central cavity of the SARS-CoV-2 spike (S) trimer, thereby inhibiting infection. Although size compatibility enables cavity access, other targeting parameters remain unclear. The S trimer features central and lateral cavities, both ∼5 nm in diameter, that can accommodate NPs. To explore factors governing cavity targeting, we compared size-matched CeO2NPs and gold NPs (AuNPs), evaluating their binding to S-trimer cavities and investigating mechanisms underlying their selective interactions. Despite comparable antiviral activity, the two NPs exhibited different binding profiles. Biolayer interferometry confirmed strong binding of both NPs to the S trimer, while only CeO2NPs selectively targeted the receptor-binding domain (RBD). CeO2NPs preferentially occupied the central cavity enriched with Asp residues. However, AuNPs bind to the lateral cavities, including the S1/S2 cleavage site, where they interact with Arg-rich motifs for furin-mediated activation of the S protein. Mechanistically, CeO2NPs achieved stable binding by coordinating with Asp carboxyl groups in the central cavity, while AuNPs bound lateral cavities primarily via electrostatic attraction with Arg residues. These findings suggest that residue-level recognition governs NP binding among sterically accessible protein cavities, with size compatibility enabling access and surface-residue matching defining binding selectivity. The insight provides a strategy for designing NPs to engage recessed features on protein surfaces previously inaccessible, enabling selective functional modulation and broader biomedical applications.

The photocatalytic hydrogen evolution activity of a model 2D covalent organic framework (TpDTz) containing a thiazolo[5,4-d]thiazole (DTz) electron acceptor and triformylphloroglucinol (Tp) electron donor groups is enhanced by combining it with well-defined catalytic centers and suitable sacrificial electron donors. Platinum nanoparticles (PtNPs) with an average diameter of 2.7 ± 0.4 nm achieve rates up to 106 000 μmol H2 g-1 h-1 (5% Pt w/w). The best system requires the use of ascorbic acid/ascorbate buffer, which has been demonstrated to enhance the photoluminescence of TpDTz by forming aggregates while efficiently extracting charges from the excited TpDTz (TpDTz*). The productive charge extraction by the PtNPs from TpDTz* is also supported by steady state and time-resolved photoluminescence studies. All these factors combined with the high catalytic activity of PtNPs catalytic centers lead to the high performance of the overall system. In addition, a noble metal-free molecular catalyst based on a tetraazamacrocyclic cobalt complex has been identified as a good alternative catalyst candidate, efficiently quenching TpDTz photoluminescence. Under optimal conditions, the cobalt-based system achieves catalytic rates of 10 400 μmol H2 g-1 h-1 (1% Co w/w), which is only three times slower than the noble metal-based PtNPs system (1% Pt w/w, 28 300 μmol H2 g-1 h-1). By using controlled catalytic centers, it was possible to identify the factors limiting the hydrogen evolution photocatalytic activity of TpDTz allowing one to minimize undesired pathways and enhancing its performance by 2 orders of magnitude.

Controlling the nucleation and growth of magnetite nanoparticles (NPs) via aqueous coprecipitation at room temperature is inherently challenging due to kinetic and thermodynamic constraints. Rapid pH increases trigger a burst nucleation event that depletes precursors before significant growth occurs, while NP surfaces are quickly passivated by water and hydroxyl ions, forming a dewetting barrier that impedes further growth. To address these challenges, we developed an innovative synthesis approach that incorporates lanthanide (Ln) cations, mainly Ce3+, together with sodium citrate into the coprecipitation process. These additives act synergistically to lower surface energy and stabilize both precursors and reaction intermediates, thereby facilitating controlled crystal growth. We systematically investigated the impact of Ln cations by fine-tuning the Ce3+ concentration, which enabled precise control over NP size, yielding diameters from 13 to 46 nm. Notably, at higher Ce3+ concentrations, multidomain nanowires are formed, with diameters reaching up to 90 nm and lengths on the micron scale. Moreover, the synthesized NPs exhibit enhanced performance in magnetic hyperthermia (MH) and peroxidase-like activity compared with those produced without Ce3+. The improved catalytic activity is attributed to accelerated Fe2+ regeneration in the reaction, mediated by the presence of the Ce4+/Ce3+ redox couple, which boosts •OH radical production. Importantly, this strategy is versatile and can be extended to other Ln cations (Eu3+, Gd3+, Er3+, Yb3+, and Lu3+), yielding single-crystal magnetite NPs of comparable sizes. Collectively, Ln-assisted synthesis addresses longstanding challenges in magnetite NP coprecipitation, providing a scalable route to high-performance magnetic NPs with tunable size and morphology. This approach not only improves control over NP growth but also broadens their potential applications in MH and catalysis.

Cancer cell survival and proliferation are correlated with increased metabolic activity and consequent oxidative stress, driving metabolic shifts that interfere with the immune response to malignant cells. This is the case of high-energy-demanding angioimmunoblastic T cell lymphoma (AITL), a highly aggressive cancer with poor survival rates, where malignant CD4+ PD-1high T cells show increased mitochondrial activity and Reactive oxygen species (ROS) accumulation. Here, we report that administration of ROS scavenging cerium oxide (CeO2) nanoparticles in an AITL preclinical mouse model leads to their preferential accumulation in the spleen, where the CD4+ PD-1high T cells driving malignancy were significantly reduced. This was accompanied by activation of previously exhausted cytotoxic CD8+ T cells, restoring their potent antitumor function. As a result, survival rates dramatically increase with no observed toxicity to healthy cells or tissues. Overall, it highlights the correlation between increased energy demand, increased mitochondrial mass, increased PD-1 expression, increased ROS production, and immune suppression and how this vicious loop can be stopped by scavenging ROS.

Gold nanoparticles (AuNPs) decorated with antigens have recently emerged as promising tools for vaccine development due to their innate ability to provide stability to antigens and modulate immune responses. In this study, we have engineered deactivated virus-like particles (VLPs) by precisely functionalizing gold cores with coronas comprising the full SARS-CoV-2 spike protein (S). Using BALB/c mice as a model, we investigated the immunogenicity of these S-AuNPs-VLPs. Our results demonstrate that S-AuNPs-VLPs consistently enhanced antigen-specific antibody responses compared to the S protein free in solution. This enhancement included higher binding antibody titers, higher neutralizing capacity of antibodies, and stronger T-cell responses. Compared to the mRNA COVID-19 vaccine, where the S protein is synthesized in situ, S-AuNPs-VLPs induced comparable binding and neutralizing antibody responses, but substantially superior T-cell responses. In conclusion, our study highlights the potential of conjugated AuNPs as an effective antigen-delivery system for protein-based vaccines targeting a broad spectrum of infectious diseases and other emergent viruses.

Conventional toxicological methods and integrated transcriptomic analysis were used to comprehensively assess the potential health hazard of residual metal nanoparticles accumulated in the body due to poor solubility.

The selective interaction of nanomaterials with proteins for protein function suppression has been reported. However, whether the nanomaterials could be used to target a three-dimensional (3D) structure of proteins for the consequent function inhibition is not defined. When SARS-CoV-2 binds to the host cell surface ACE2 receptor, the spike protein trimer changes to an "Open State" which forms a 5 nm cavity structure, consequently exposing the receptor binding domain (RBD) for the following viral infection. We found that the 3 nm cerium oxide nanoparticles (CeO2@3) showed a better anti-SARS-CoV-2 effect than 30 nm cerium oxide nanoparticles (CeO2@30). We performed a series of experiments and demonstrated that the CeO2@3 could target the 5 nm spike protein trimer cavity and tightly bind with the RBD, thus effectively blocking the following virus-cell interaction and rendering CeO2@3 as an effective anti-viral agent. As all coronaviruses possess similar spike protein structures as homologous proteins, CeO2@3 can be used as a broad-sperm anti-coronavirus nanodrug candidate by targeting the spike protein 3D structure. This work, for the first time, demonstrated that rationally engineered inorganic nanomaterials can be used to specifically target a 3D structure of a certain protein for function inhibition, thus providing a novel methodological approach and paving the way for future molecular targeting nanodrug candidate design.

The label-free imaging of inorganic nanoparticles (NPs) using confocal laser scanning microscopy (CLSM) provides a powerful and versatile tool for studying interactions between NPs and biological systems. Without the need for exogenous labels or markers, it simply benefits from the differential scattering of visible photons between biomaterials and inorganic NPs. Validation experiments conducted on fixed and living cells in real-time, as well as mouse tissue sections following parenteral administration of NPs. Additionally, by incorporating reporter fluorophores and utilizing both reflectance and fluorescence imaging modalities, the method enables high-resolution multiplex imaging of cellular structures and NPs. Different sizes and concentrations of Au NPs are tested as for Ag, Fe3O4, and CeO2 NPs, all with biological interest. Overall, the comprehensive study of NP imaging by confocal microscopy in reflectance mode provides valuable insights and tools for researchers interested in monitoring the nano-bio interactions. Label-free imaging of inorganic nanoparticles through confocal laser scanning microscopy offers a versatile approach to studying nano-bio interactions. This method, based on photon scattering, eliminates the need for labels. Validation experiments on cells and tissue section post-NP administration demonstrate real-time applications. Using reporter fluorophores and both reflectance and fluorescence imaging, the method achieves high-resolution multiplex imaging of cellular structures and NPs. image

Due to advances in additive manufacturing and prototyping, affordable and rapid microfluidic sensor-integrated assays can be fabricated using additive manufacturing, xurography and electrode shadow masking to create versatile platform technologies aimed toward qualitative assessment of acute cytotoxic or cytolytic events using stand-alone biochip platforms in the context of environmental risk assessment. In the current study, we established a nasal mucosa biosensing platform using RPMI2650 mucosa cells inside a membrane-integrated impedance-sensing biochip using exclusively rapid prototyping technologies. In a final proof-of-concept, we applied this biosensing platform to create human cell models of nasal mucosa for monitoring the acute cytotoxic effect of zinc oxide reference nanoparticles. Our data generated with the biochip platform successfully monitored the acute toxicity and cytolytic activity of 6 mM zinc oxide nanoparticles, which was non-invasively monitored as a negative impedance slope on nasal epithelial models, demonstrating the feasibility of rapid prototyping technologies such as additive manufacturing and xurography for cell-based platform development.

Water is essential for innumerable natural, technological, and industrial activities. The advent of nanotechnology has allowed a better understanding of water at the nanoscale and its interaction with bio-organic, inorganic, and nanostructured interfaces. This knowledge offers clues to designing new nanomaterials or nanotechnological devices. Nowadays, a wide range of nanomaterials provides very efficient and tunable interfacial processes that can be exploited for many applications, including water remediation. Therefore, in this article, we survey the more representative nanomaterials and interfacial phenomena to enhance water purification processes. The article starts with the fundamental concepts of water at the nanoscale and its crucial role in interacting with surfaces. Then we discuss relevant nanointerfacial strategies to alleviate the problem of water pollution and shortage.

Introduction Gene therapy holds promise to cure various diseases at the fundamental level. For that, efficient carriers are needed for successful gene delivery. Synthetic ‘non-viral’ vectors, as cationic polymers, are quickly gaining popularity as efficient vectors for transmitting genes. However, they suffer from high toxicity associated with the permeation and poration of the cell membrane. This toxic aspect can be eliminated by nanoconjugation. Still, results suggest that optimising the oligonucleotide complexation, ultimately determined by the size and charge of the nanovector, is not the only barrier to efficient gene delivery. Methods We herein develop a comprehensive nanovector catalogue comprising different sizes of Au NPs functionalized with two different cationic molecules and further loaded with mRNA for its delivery inside the cell. Results and Discussion Tested nanovectors showed safe and sustained transfection efficiencies over 7 days, where 50 nm Au NPs displayed the highest transfection rates. Remarkably, protein expression was increased when nanovector transfection was performed combined with chloroquine. Cytotoxicity and risk assessment demonstrated that nanovectors are safe, ascribed to lesser cellular damage due to their internalization and delivery via endocytosis. Obtained results may pave the way to design advanced and efficient gene therapies for safely transferring oligonucleotides.

Nanoparticle (NP) pharmacokinetics significantly differ from traditional small molecule principles. From this emerges the need to create new tools and concepts to harness their full potential and avoid unnecessary risks. Nanoparticle pharmacokinetics strongly depend on size, shape, surface functionalisation, and aggregation state, influencing their biodistribution, accumulation, transformations, and excretion profile, and hence their efficacy and safety. Today, while NP biodistribution and nanoceria biodistribution have been studied often at short times, their long-term accumulation and excretion have rarely been studied. In this work, 3 nm nanoceria at 5.7 mg/kg of body weight was intravenously administrated in a single dose to healthy mice. Biodistribution was measured in the liver, spleen, kidney, lung, brain, lymph nodes, ovary, bone marrow, urine, and faeces at different time points (1, 9, 30, and 100 days). Biodistribution and urinary and faecal excretion were also studied in rats placed in metabolic cages at shorter times. The similarity of results of different NPs in different models is shown as the heterogeneous nanoceria distribution in organs. After the expectable accumulation in the liver and spleen, the concentration of cerium decays exponentially, accounting for about a 50% excretion of cerium from the body in 100 days. Cerium ions, coming from NP dissolution, are most likely excreted via the urinary tract, and ceria nanoparticles accumulated in the liver are most likely excreted via the hepatobiliary route. In addition, nanoceria looks safe and does not damage the target organs. No weight loss or apathy was observed during the course of the experiments.

Metal clusters supported on TiO 2 are widely used in many photocatalytic applications, including pollution control and production of solar fuels. Besides high photoactivity, stability during the photoreaction is another essential quality of high-performance photocatalysts, however systematic studies on this attribute are absent for metal clusters supported on TiO 2 . Here we have studied, both experimentally and with first-principles simulation methods, the stability of Pt, Pd and Au clusters prepared by ball milling on nanoshaped anatase nanoparticles preferentially exposing {001} (plates) and {101} (bipyramids) facets during the photogeneration of hydrogen. It is found that Pt/TiO 2 exhibits superior stability than Pd/TiO 2 and Au/TiO 2 , and that {001} facet-based photocatalysts always are more stable than their {101} analogous regardless of the considered metal species. The loss of stability associated with cluster sintering, which is facilitated by the transfer of photoexcited carriers from the metal species to the neighbouring Ti and O atoms, most significantly and detrimentally affects the H 2 -evolution photoactivity.

Titanium dioxide nanoparticles (TiO2 NPs) are one of the main sources of the nanoparticulate matter exposure to humans. Although several studies have demonstrated their potential toxic effects, the real nature of the correlation between NP properties and their interaction with biological targets is still far from being fully elucidated. Here, engineered TiO2 NPs with various geometries (bipyramids, plates, and rods) have been prepared, characterized and intravenously administered in healthy mice. Parameters such as biodistribution, accumulation, and toxicity have been assessed in the lungs and liver. Our data show that the organ accumulation of TiO2 NPs, measured by ICP-MS, is quite low, and this is only partially and transiently affected by the NP geometries. The long-lasting permanence is exclusively restricted to the lungs. Here, bipyramids and plates show a higher accumulation, and interestingly, rod-shaped NPs are the most toxic, leading to histopathological pulmonary alterations. In addition, they are also able to induce a transient increase in serum markers related to hepatocellular injury. These results indicate that rods, more than bipyramidal and spherical geometries, lead to a stronger and more severe biological effect. Overall, small physico-chemical differences can dramatically modify both accumulation and safety.

Cerium oxide nanoparticles (CeO2NPs) have exceptional catalytic properties, rendering them highly effective in removing excessive reactive oxygen species (ROS) from biological environments, which is crucial in safeguarding these environments against radiation-induced damage. Additionally, the Ce atom's high Z number makes it an ideal candidate for utilisation as an X-ray imaging contrast agent. We herein show how the injection of albumin-stabilised 5 nm CeO2NPs into mice revealed substantial enhancement in X-ray contrast, reaching up to a tenfold increase at significantly lower concentrations than commercial or other proposed contrast agents. Remarkably, these NPs exhibited prolonged residence time within the target organs. Thus, upon injection into the tail vein, they exhibited efficient uptake by the liver and spleen, with 85% of the injected dose (%ID) recovered after 7 days. In the case of intratumoral administration, 99% ID of CeO2NPs remained within the tumour throughout the 7-day observation period, allowing for observation of disease dynamics. Mass spectrometry (ICP-MS) elemental analysis confirmed X-ray CT imaging observations.

Using surfactants in the galvanic replacement reaction (GRR) offers a versatile approach to modulating hollow metal nanocrystal (NC) morphology and composition. Among the various surfactants available, quaternary ammonium cationic surfactants are commonly utilised. However, understanding how they precisely influence morphological features, such as the size and void distribution, is still limited. In this study, we aim to uncover how adding different surfactants—CTAB, CTAC, CTApTS, and PVP—can fine-tune the morphological characteristics of AuAg hollow NCs synthesised via GRR at room temperature. Our findings reveal that the halide counterion in the surfactant significantly controls void formation within the hollow structure. When halogenated surfactants, such as CTAB or CTAC, are employed, multichambered opened nanoboxes are formed. In contrast, with non-halogenated CTApTS, single-walled closed nanoboxes with irregularly thick walls form. Furthermore, when PVP, a polymer surfactant, is utilised, changes in concentration lead to the production of well-defined single-walled closed nanoboxes. These observations highlight the role of surfactants in tailoring the morphology of hollow NCs synthesised through GRR.

Endotoxins or lipopolysaccharides (LPS), found in the outer membrane of Gram-negative bacterial cell walls, can stimulate the human innate immune system, leading to life-threatening symptoms. Therefore, regulatory limits for endotoxin content apply to injectable pharmaceuticals, and excess LPS must be removed before commercialization. The majority of available endotoxin removal systems are based on the non-specific adsorption of LPS to charged and/or hydrophobic surfaces. Albeit effective to remove endotoxins, the lack of specificity can result in the unwanted loss of essential proteins from the pharmaceutical formulation. In this work, we developed microparticles conjugated to anti-Lipid A antibodies for selective endotoxin removal. Anti-Lipid A particles were characterized using flow cytometry and microscopy techniques. These particles exhibited a depletion capacity > 6 ×103 endotoxin units/mg particles from water, as determined with two independent methods (Limulus Amebocyte Lysate test and nanoparticle tracking analysis). Additionally, we compared these particles with a non-specific endotoxin removal system in a series of formulations of increasing complexity: bovine serum albumin in water < insulin in buffer < birch pollen extracts. We demonstrated that the specific anti-Lipid A particles show a higher protein recovery without compromising their endotoxin removal capacity. Consequently, we believe that the specificity layer integrated by the anti-Lipid A antibody could be advantageous to enhance product yield.

The long quest for efficient drug administration has been looking for a universal carrier that can precisely transport traditional drugs, new genomic and proteic therapeutic agents. Today, researchers have found conditions to overcome the two main drug delivery dilemmas. On the one side, the versatility of the vehicle to efficiently load, protect and transport the drug and then release it at the target place. On the other hand, the questions related to the degree of PEGylation which are needed to avoid nanoparticle (NP) aggregation and opsonization while preventing cellular uptake. The development of different kinds of lipidic drug delivery vehicles and particles has resulted in the development of ionizable lipid nanoparticles (iLNPs), which can overcome most of the typical drug delivery problems. Proof of their success is the late approval and massive administration as the prophylactic vaccine for SARS-CoV-2. These ILNPs are built by electrostatic aggregation of surfactants, the therapeutic agent, and lipids that self-segregate from an aqueous solution, forming nanoparticles stabilized with lipid polymers, such as PEG. These vehicles overcome previous limitations such as low loading and high toxicity, likely thanks to low charge at the working pH and reduced size, and their entry into the cells via endocytosis rather than membrane perforation or fusion, always associated with higher toxicity. We herein revise their primary features, synthetic methods to prepare and characterize them, pharmacokinetic (administration, distribution, metabolization and excretion) aspects, and biodistribution and fate. Owing to their advantages, iLNPs are potential drug delivery systems to improve the management of various diseases and widely available for clinical use.