ABSTRACT Persistent luminescence (PersL) materials exhibit prolonged emission of light, lasting from seconds to hours after stopping the excitation. At the nanoscale, they have attracted considerable interest for applications in in vivo imaging, photodynamic therapy, and biosensing. In 2023, an unexpected phenomenon was reported: a dose‐dependent enhancement of PersL in ZnGa 2 O 4 :Cr 3+ nanoparticles (ZGO:Cr 3+ NPs) upon exposure to hydrogen peroxide (H 2 O 2 ), opening a novel in vitro strategy for biomolecule detection. This strategy allows for fast and sensitive qualitative and quantitative detection of H 2 O 2 that is of major diagnostic relevance as it results from enzymatic processes and serves as a key biomarker in a wide range of diseases. This study investigates the fundamental mechanism underlying H 2 O 2 ‐induced PersL enhancement in ZGO:Cr 3+ NPs using a combination of structural, optical, photochemical, and surface chemistry analyses. It is demonstrated that under UV‐C irradiation, ZGO:Cr 3+ NPs produce photoelectrons initiating a redox reaction with adsorbed H 2 O 2 . Produced hydroxyl radicals ( • OH) interact with the nanoparticle surface to generate additional charge carriers, ultimately intensifying and prolonging Cr 3+ luminescence. These results reveal a previously unknown charging pathway in persistent phosphors, combining photocatalysis and chemiluminescence, and lay the foundations for advanced applications in biodetection and other emerging photonics technologies.

Assessing the environmental risks of emerging contaminants related to new technologies remains a major challenge due to the diversity of pollutants, their complex interactions, and the limitations of conventional testing frameworks. Among these contaminants, engineered nanomaterials (ENMs) stand out for their unique surface reactivities and transformation pathways, which can significantly alter their behavior and that of co-occurring pollutants. Although many studies have addressed the toxicity and fate of individual ENMs, real-world scenarios often involve complex mixtures, whose combined effects are less investigated. This study addresses this gap by investigating the fate, behavior, and ecological impacts of a mixture of two representative metal oxide ENMs i.e. an industrial TiO2 and a combustion-derived CeO2. This study shows that under environmentally relevant conditions using freshwater mesocosms, these two ENMs undergo primary hetero-aggregation. Co-exposure of the freshwater snail Planorbarius corneus revealed that ENM aggregates (homo- or primary hetero-aggregates) interact with egg layings, potentially affecting early developmental stages, while slight but measurable uptakes were also observed in co-exposed adult snails. Importantly, no quenching of reactive oxygen species generated by the photocatalytic TiO2 was detected in the presence of CeO2, suggesting that the combusted CeO2 does not mitigate potentially TiO2-induced phototoxicity. These findings underscore the importance of considering ENM mixtures in environmental risk assessments and the relevance of mesocosm experiments to capture realistic exposure scenarios. Future studies should prioritize investigating how unique surface reactivities and transformation mechanisms of ENM mixtures shape their ecological impacts throughout their life cycles.

Persistent luminescence (PersL) materials exhibit prolonged emission of light, lasting from seconds to hours after stopping the excitation. At the nanoscale, they have attracted considerable interest for applications in in vivo imaging, photodynamic therapy, and biosensing. In 2023, an unexpected phenomenon was reported: a dose-dependent enhancement of PersL in ZnGa2O4:Cr3+ nanoparticles (ZGO:Cr3+ NPs) upon exposure to hydrogen peroxide (H2O2), opening a novel in vitro strategy for biomolecule detection. This strategy allows for fast and sensitive qualitative and quantitative detection of H2O2 that is of major diagnostic relevance as it results from enzymatic processes and serves as a key biomarker in a wide range of diseases. This study investigates the fundamental mechanism underlying H2O2-induced PersL enhancement in ZGO:Cr3+ NPs using a combination of structural, optical, photochemical, and surface chemistry analyses. It is demonstrated that under UV-C irradiation, ZGO:Cr3+ NPs produce photoelectrons initiating a redox reaction with adsorbed H2O2. Produced hydroxyl radicals (center dot OH) interact with the nanoparticle surface to generate additional charge carriers, ultimately intensifying and prolonging Cr3+ luminescence. These results reveal a previously unknown charging pathway in persistent phosphors, combining photocatalysis and chemiluminescence, and lay the foundations for advanced applications in biodetection and other emerging photonics technologies.

Correction for ‘Beyond single nanomaterial exposure: investigating the fate of a TiO 2 and CeO 2 nanomaterial mixture in freshwater mesocosms’ by Amazigh Ouaksel et al. , Environ. Sci.: Nano , 2026, https://doi.org/10.1039/d5en00871a.

Exposure of a freshwater ecosystem to a mixture of two relevant engineered nanomaterials revealed distinct aggregation dynamics, behavior, and fate.

This study presents an investigation into the surfactant-free synthesis of copper oxide nanoparticles (CuONPs) via a precipitation method, focusing on how various experimental parameters influence nanoparticle characteristics. By varying key parameters, such as precursor type and concentration, pH, and reaction temperature, the work reveals their impact on nanoparticle size, morphology, and crystallinity. The results highlight that the precursor's counter-ion and Cu/OH ratio play key roles in directing the particle shape, while an increased copper concentration favored rod-like structures through an oriented attachment phenomenon. A temperature-dependent phase transition was observed for the first time, illustrating a metastable flake-like intermediate that transforms into spherical nanoparticles at high temperatures. This study proposes a detailed growth mechanism, identifying two temperature-dependent pathways, slow CuO condensation at low temperatures and competing oxolation/olation reactions at high temperatures. Overall, this work establishes a reproducible framework for tailoring the morphology of CuONPs under mild conditions.

Persistent phosphors have attracted significant attention for their potential application in safety signage, road markings, data storage, anti-counterfeiting technologies, and biomedical fields. However, despite the significant advancements in room-temperature persistent phosphors and deep-trap materials for information storage, development of low-temperature persistent phosphors with strong afterglow emission remains a considerable challenge. In this study, we successfully modified the trap depth distribution in ZnGa2O4: Cr3+ nanoparticles (ZGO:Cr NPs) by carefully controlling the synthesis conditions in order to develop nanoscale persistent phosphors tailored for various temperature-dependent applications. ZnGa2O4: Cr3+ nanoparticles were synthesized via a rapid, facile, and environmentally friendly microwave-assisted hydrothermal method. A subsequent thermal treatment at temperatures of 500 and 700 degrees C was employed to further modify their structure and, consequently, their optical properties. Notably, the ZGO:Cr NPs without any subsequent calcination (ZGO MW) exhibit strong and long-lasting luminescence at cryogenic temperatures (15-200 K) and they show great potential for applications requiring continuous cooling at liquid nitrogen temperatures, such as the cryopreservation of biological agents, viruses, and tissues. In contrast, ZGO:Cr NPs calcined at 700 degrees C (ZGO 700) demonstrate stabilization of deeper traps, with activation energies near room temperature, which shows promise for conventional persistent luminescence applications requiring small particle sizes (<10 nm). Meanwhile, ZGO:Cr NPs calcined at 500 degrees C (ZGO 500) display a broad distribution of traps and a remarkably wide operational range (15-400 K), due to the coexistence of multiple Cr3+ environments, making it highly suitable for applications requiring stable persistent luminescence behaviour at very wide range of temperatures.

Chromium-doped zinc gallate (ZnGa2O4:Cr3 +) nanoparticles (ZGO) show promising potential for antigen immunodetection using persistent luminescence, thereby reducing autofluorescence interference. Recently, we have shown that ZGO prepared by hydrothermal treatment at 120 degrees C for 24 h can be used for in vitro biodetection in simple media such as phosphate-buffered saline. In this study, we investigated the effect of the protocol used to synthesize these ZGO nanoparticles, using a hydrothermal treatment at 220 degrees C for different durations (6 h, 12 h, and 24 h), followed by calcination at 500 degrees C. The nanoparticle size determined by transmission electron microscopy after grinding and centrifugation was found to be around 15 nm. The persistent luminescence signal of the ZGO nanoparticles varied with the hydrothermal synthesis conditions. Moreover, in the presence of H2O2, these nanoparticles show a signal enhancement dependent on the hydrothermal duration, with a 12 h treatment showing the highest 8-fold luminescence increase in the presence of H2O2 produced by glucose oxidase mediated glucose degradation. Based on these results, these non-functionalized nanoparticles were successfully used to develop a persistent luminescence-based sandwich immunoassay for autofluorescence-free detection of antigens in undiluted human serum samples, using rabbit IgG as a model antigen. This study highlights the promising potential for biosensing applications of persistent ZGO nanophosphors for IgG detection in a complex medium (undiluted human serum), with a linear range from 1 ng mL- 1 to 104 ng mL- 1 and a limit of detection of 0.01 ng mL- 1. The present optimization of ZGO nanophosphor synthesis offers promising prospects for medical diagnostics due to their increased sensitivity and ability to eliminate autofluorescence interference, as well as their ease of use, since no functionalization of the ZGO NPs is required before use.

Interaction between nanoparticles (NPs) and cells is a key concern in nanotechnology-based biomedical applications. This study investigates cytocompatible silver sulfide (Ag2S) quantum dots (QDs), which emit strongly in the second near-infrared (NIR II) region, for their potential in image-guided therapies. Since cellular microenvironments contain acidic pH, hydrogen peroxide (H2O2), and reactive oxygen species (ROS), which can affect luminescence, Ag2S NPs (AS NPs) coated with three ligands: DTDTPA (dithiolated diethylene triamine pentaacetic acid), 11MUA (11 mercaptoundecanoic acid), and PEG (polyethylene glycol) were studied in fibroblast cells over 9 days. Long term photoluminescence (PL) tracking showed distinct behavior. AS DTDTPA and AS 11MUA exhibited increasing uptake but decreasing PL, while AS PEG showed both enhanced PL and uptake over time. No significant changes in NP size or structure explained the PL differences. Exposure to H2O2 revealed that AS DTDTPA and AS 11MUA lost PL due to oxidation or shell detachment, reducing surface passivation. In contrast, AS PEG showed intensified PL, possibly from removal of metallic silver and increased PL lifetime. These results highlight time dependent PL changes in cellular and oxidative environments. DTDTPA and PEG coatings may act as ROS scavenger and promoter, respectively, while enabling NIR II imaging and offering insights into NP design for stable optical tracking and therapeutic use.

In persistent luminescent materials, energy can be stored under irradiation by controlled traps/defects. This energy is released at ambient temperature for long time by light emission once the excitation has been stopped. The search for innovative materials with improved properties is at the heart of the work and has recently led to several new persistent luminescence materials either as nanomaterials for sensors - and in biosensing and bioimaging- or as single crystals for various applications data storage or as jewels-. These persistent luminescent materials require identification and control of the depth of the traps and the studies of charge/discharge mechanisms.

The use of zinc gallate nanoparticles (ZnGa 2 O 4 :Cr 3+ ) (ZGO‐NPs) presents significant potential for improving the sensitivity in enzyme‐linked immunosorbent assays (ELISA). The persistent luminescence signal increase of these nanoparticles in the presence of hydrogen peroxide (H 2 O 2 ) offers advantages for the sensitive detection of biomolecules. Herein, different conditions of ZGO synthesis have been investigated by varying the hydrothermal reaction duration (6, 12, and 24 h) and examining its impact in the presence of H 2 O 2 . These nanoparticles have been integrated into ELISA assays, using as target antigen IgG. The lowest limit of detection (LOD) of 0.2 pg mL −1 is observed for ZGO‐NPs prepared during 12 h (ZGO2), and with a detection range from 1 to 1000 pg mL −1 . The impact of covalently functionalizing these nanoparticles has then been assessed. First using glucose oxidase (GOx) and the detection antibody (Ab D ) linked to PEGylated ZGO‐NPs, named ZGO‐GOx‐Ab D . Alternatively, only the detection antibody is linked to the PEG ZGO‐NPs, named ZGO‐Ab D . The results show a significant lowering of the LOD when using the functionalized ZGO2 NPs and also highlight the impact of the signal amplification by H 2 O 2 . Specifically, when using ZGO2‐GOx‐Ab D incubated with glucose to produce H 2 O 2 , or with ZGO2‐Ab D to which H 2 O 2 was added, the LODs are ≈98 and 56 fg mL −1 respectively, with detection ranges from 0.01 to 100 pg mL −1 .

A new method is presented for the in vitro detection of glucose using glucose oxidase (GOx) covalently linked to persistent luminescent nanoparticles (PLNPs). This method ensures both sensitive and specific glucose detection by exploiting the enhanced luminescence of PLNPs in the presence of H2O2, generated by an enzymatic reaction. To this end, three different PLNPs composed of ZnGa2O4:Cr3+ (ZGO) nanoparticles are prepared by hydrothermal synthesis at 120 degrees C for 6 h (ZGO1), 12 h (ZGO2), and 24 h (ZGO3), followed by a calcination at 500 degrees C, resulting in nanoparticles with an average hydrodynamic diameter of 100 nm +/- 5 nm after grinding and centrifugation. These nanoparticles are efficiently covalently functionalized with GOx, via a PEG linker. Following the production of H2O2 by the enzymatic reaction between GOx bound to the ZGO surface and glucose present in 100-fold diluted serum, a significant increase in the persistent luminescent signal is observed. This phenomenon is most pronounced for ZGO2, for which a detection limit of 0.01 mu m and a detection range from 0.05 to 1 mu m is obtained. These results demonstrate the innovative potential of this new technique in glucose monitoring, opening up new avenues for real-time monitoring and effective management of diabetes.

Interaction between nanoparticles (NPs) and cells is a key concern in nanotechnology‐based biomedical applications. This study investigates cytocompatible silver sulfide (Ag2S) quantum dots (QDs), which emit strongly in the second near‐infrared (NIR II) region, for their potential in image‐guided therapies. Since cellular microenvironments contain acidic pH, hydrogen peroxide (H2O2), and reactive oxygen species (ROS), which can affect luminescence, Ag2S NPs (AS NPs) coated with three ligands: DTDTPA (dithiolated diethylene triamine pentaacetic acid), 11MUA (11 mercaptoundecanoic acid), and PEG (polyethylene glycol) were studied in fibroblast cells over 9 days. Long term photoluminescence (PL) tracking showed distinct behavior. AS DTDTPA and AS 11MUA exhibited increasing uptake but decreasing PL, while AS PEG showed both enhanced PL and uptake over time. No significant changes in NP size or structure explained the PL differences. Exposure to H2O2 revealed that AS DTDTPA and AS 11MUA lost PL due to oxidation or shell detachment, reducing surface passivation. In contrast, AS PEG showed intensified PL, possibly from removal of metallic silver and increased PL lifetime. These results highlight time dependent PL changes in cellular and oxidative environments. DTDTPA and PEG coatings may act as ROS scavenger and promoter, respectively, while enabling NIR II imaging and offering insights into NP design for stable optical tracking and therapeutic use.

Persistent luminescence (PersL) nanoparticles emit a signal that lasts long after the excitation has ended, enabling highly sensitive bioimaging without background noise. By using UV light as the excitation source prior to injection, a strong PersL signal can be detected in vivo before disappearing within a few hours. For long-term imaging, we have shown in the past that visible LED can be used to re-excite ZnGa1.995Cr0.005O4 (ZGO:Cr3+) nanoparticles in vivo, producing a signal intensity that is, however, much lower compared to the signal obtained after the UV pre-excitation method. This lower signal intensity of the nanoprobe when using a visible LED may prevent its detection in some cases. Herein, we report an improvement in visible LED excitation efficiency using PersL Zn1.33Ga1.335Cr0.005Sn0.33O4 (ZGSO:Cr3+) nanoparticles. We fully compared ZGSO:Cr3+ and the original ZGO:Cr nanoparticles in terms of structure, optical properties and bio-imaging potential. Co-doping with tin strongly increases persistent luminescence, even at the nanoscale. In vivo imaging results showed that ZGSO:Cr3+ exhibited an approximately 3-fold signal enhancement over ZGO:Cr3+ using UV pre-excitation. More interestingly, when using LED excitation, the signal intensity of ZGSO: Cr3+ is more than 10 times higher than that of ZGO:Cr3+, making ZGSO nanoparticles much easier to detect. ZGSO:Cr nanoparticles can be surface-modified with PEG to produce nanoprobes with much longer residence time in blood. This unique comparison between the two compositions makes ZGSO:Cr3+ a more effective imaging diagnostic probe than the original ZGO:Cr3+ nanoparticles, opening up new applications for in vivo diagnostics.

Persistent luminescence (PersL) is widely used for near infrared (NIR-I, 650-950 nm) imaging as they allow getting images without background. Bio-imaging in the second shortwave-infrared region SWIR-II (NIR-II, 1000-1400 nm) is less widespread but is growing as it offers the advantages of low photon scattering, increased in vivo penetration depth, and improved imaging clarity. In this work, the preparation and the complete optical properties of a new material is reported, Zn1.33Ga1.33Ni0.005Cr0.005Sn0.33O3.995 (ZGSO:Cr3+, Ni2+) able of emitting in both deep-red/NIR-I and SWIR (NIR-II) and shows its potential in bioimaging. ZGSO:Cr3+, Ni2+ can be excited using different sources such as X-rays, UV, and visible light to emit persistent signals in dual biological windows (dual-BW). By integrating an energy transfer process from Cr3+ to Ni2+ within this newly synthesized material, the influence of co-dopants on signal intensity and emission wavelengths is sought to explore. PersL at approximate to 700 nm (NIR-I) and approximate to 1300 nm (NIR-II) have been tested in preliminary bioimaging experiments using different protocols, allowing signal detection with good spatial resolution and depth sensitivity. The dual-BW PersL imaging strategy expands the toolbox for highly accurate analysis and has, for the first time, allowed access to accurately high-resolution sensing, and tracing.

Significant achievements have been reported in the last few years regarding the stabilization and functionalisation of gold nanoparticles (AuNPs), mainly through the use of thiols and imidazolylidene N-heterocyclic carbenes capping ligands. Herein, we report that mesoionic carbenes (MICs) ligands, based on the 1,2,3-triazol-5-ylidene scaffold, allow the expeditive preparation of AuNPs of exceptional stability through a simple and straightforward one-pot protocol directly from triazolium salts and discrete Au(III) sources. Control over the size of the AuNPs has been achieved by varying the Au/ligand ratio as well as the nature of the triazolium salts, the latter being facilitated by the ease of synthesis of the MIC precursors through click chemistry. Characterisation of these MIC-AuNPs by X-ray photoelectron spectroscopy (XPS) hints at the exclusive presence of MICs on the nanoparticle surface.

To reduce the environmental impact of supported catalyst production in compliance with the recommendations of the UN's 12th objective, which encourages more sustainable consumption and production patterns, we propose to revisit solgel chemistry in a more frugal mode. The principle of frugal innovation is to simplify products and processes, eliminate complexities to make solutions easier to understand and use, and reduce production costs. By this way, the synthesis of rutheniumbased catalysts supported on gamma-AlOOH and gamma-Al2O3 is revised via solvent-free sol-gel chemistry. Such catalysts are successfully prepared in one-pot preparation of the active phase and the support using Ru(acac)(3)/Al alkoxide that requires no sacrificial organic pore-generating agent, no washing, and no filtration and produces no liquid waste. The mixed Ru/Al precursor is hydrolyzed with a stoichiometric amount of water without any solvent. The obtained materials containing 1 and 3% Ru/Al molar ratios have high specific surface areas, from 300 to 690 m(2)center dot g(-1) and exhibit well dispersed NPs of 1-4 nm on.-AlOOH with interesting CO2 methanation activity and 100% CH4 selectivity. This proves that a frugal synthesis approach can do as well as traditional synthesis methods while having a much lower environmental impact (cE-factor, water consumption, and energy consumption are 24, 69, and 24 to 42 times lower, respectively) than the standard multistep protocol..

Biomedical photothermal therapy with optical nanoparticles is based on the conversion of optical energy into heat through three steps: optical absorption, thermal conversion of the absorbed energy and heat transfer to the surrounding medium. The light-to-heat conversion efficiency (LHCE) has become one of the main metrics to quantitatively characterize the last two steps and evaluate the merit of nanoparticules for photothermal therapy. The estimation of the LHCE is mostly performed by monitoring the temperature evolution of a solution under laser irradiation. However, this estimation strongly depends on the experimental set-up and the heat balance model used. We demonstrate here, theoretically and experimentally, that the LHCE at multiple wavelengths can be efficiently and directly determined, without the use of models, by calibrated photoacoustic spectroscopy. The method was validated using already characterized colloidal suspensions of silver sulfide nanoparticles and maghemite nanoflowers and an uncertainty of 3 to 7% was estimated for the LHCE determination. Photoacoustic spectroscopy provides a new, precise and robust method of analysis of the photothermal capabilities of aqueous solutions of nanoagents.