Background Electronic cigarette aerosols contain complex chemical mixtures derived from e-liquid ingredients (e.g. nicotine, solvents, and flavoring agents) and from neoformed substances generated during heating (e.g. aldehydes or metals). Their toxicological impact remains only partially characterized. This presentation summarizes the findings of the national evaluation conducted by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES), which identified and classified more than 1,000 potentially hazardous substances possibly present in emissions. It then illustrates cardiovascular toxicity through recent preclinical evidence, including a focused example involving cinnamaldehyde-containing flavors. Methods The ANSES assessment relies on a standardized approach combining: (i) exhaustive collection and characterization of ingredients declared by manufacturers to regulatory authorities; (ii) analytical quantification of aerosol emissions generated under controlled puffing regimes; and (iii) toxicological prioritization integrating exposure levels with hazard classifications. Cardiovascular relevance was demonstrated by summarizing key results from a recent preclinical review of vascular effects of e-cigarette exposure, and by analyzing experimental in vitro data on cinnamaldehyde toxicity in aortic smooth muscle cells. Results ANSES identified numerous hazardous substances in both ingredients and emissions, including carbonyls formed by thermal decomposition, metals, and several reactive flavoring compounds. A subset exceeded thresholds of toxicological concern under realistic exposure conditions. Preclinical evidence consistently reported endothelial dysfunction, oxidative stress, inflammation, and early pro-atherogenic alterations following e-cigarette aerosol exposure. Finally, among flavorings, cinnamaldehyde shows particularly high reactivity: recent in-vitro work demonstrates enhanced inflammatory signaling at concentrations compatible with those generated by flavored vaping emissions. Conclusions Current evidence indicates that multiple compounds present in e-cigarette emissions, including both ingredients and neoformed substances, pose potential toxicological risks based on their hazard. Cardiovascular endpoints appear particularly sensitive, and cinnamon-derived flavoring agents may cause vascular effects. Ongoing chemical characterization and mechanistic studies remain essential to refine hazard and then risk assessment.

Optimizing pulmonary exogenous surfactant delivery remains a critical challenge in neonatal care, particularly for achieving uniform distal lung deposition while minimizing airway obstruction. This study aimed to establish a preclinical imaging framework for quantitative assessment of exogenous surfactant lung distribution in vivo using contrast-enhanced ultrashort echo time (UTE) MRI and to evaluate the impact of physiological processes on surfactant retention and localization. Six juvenile rabbits received intratracheal instillation of a gadolinium-enhanced surfactant solution under clinically relevant conditions. High-resolution, motion-robust 3D UTE MRI datasets were acquired, enabling voxel-wise quantification of signal enhancement, gadolinium concentration, and spatial surfactant lung distribution. Peripheral volume fraction, laterality index, and distality index were computed to characterize deposition homogeneity and distal penetration. In vivo measurements were compared with previously reported ex vivo data from isolated rabbit thoraces. Quantitative MRI enabled precise mapping of surfactant within peripheral alveolar regions. Forty-two percent of the instilled dose was retained in vivo, compared with 93.5% ex vivo. Laterality indices confirmed balanced right-left distribution, while distality indices demonstrated consistent peripheral deposition. The radial UTE sequence minimized motion artifacts and enabled robust voxel-wise quantification under physiological breathing conditions. Quantitative in vivo MRI provides a sensitive and reliable method for assessing pulmonary surfactant delivery, spatial distribution, distal penetration, and homogeneity of deposition. Comparison with ex vivo data underscores the role of physiological processes in surfactant retention. This framework supports optimization of administration strategies in preclinical models and may be extended to other intrapulmonary therapies, establishing a versatile imaging platform for translational research.

Aerosol delivery during invasive mechanical ventilation is influenced by multiple factors, including nebulizer type and ventilatory settings. Current intensive care unit (ICU) guidelines generally provide limited recommendations regarding modification of ventilatory parameters during aerosol administration because available evidence remains heterogeneous. However, most available data originate from simplified in vitro models or evaluate individual components of aerosol delivery, limiting understanding of how aerosol characteristics interact with respiratory mechanics under realistic ventilatory conditions. This study evaluated how inspiratory flow and inspiratory-to-expiratory (I:E) ratio influence aerosol transport and respiratory tract deposition according to nebulizer technology using a controlled preclinical model. The objective was not to establish superiority between commercial devices, but to determine whether ventilatory parameters differently modulate aerosol fate depending on aerosol generation technologies. Using a validated ex vivo porcine respiratory model under volume-controlled ventilation, we assessed the impact of inspiratory flow (35 vs. 60 L/min) and I:E ratio (1:2 vs. 1:3) on respiratory tract deposition. Experiments were performed with a vibrating mesh nebulizer (VMN) and a jet nebulizer (JN) placed 15 cm upstream of the Y-piece, with active heated humidification. Deposition was measured by planar scintigraphy with radiolabeled aerosol and a mass balance approach. VMN showed significantly higher delivery efficiency than JN in all conditions. With VMN, lower inspiratory flow increased respiratory tract deposition (57% ± 8% vs. 45% ± 5%, p = 0.022), and a longer expiratory phase (I:E 1:3 vs. 1:2) further improved deposition (60% ± 9% vs. 45% ± 5%, p < 0.0001), with reduced losses in the inspiratory limb. In contrast, JN had low output and no significant variation across settings. Ventilatory parameters significantly influence aerosol deposition with VMN but not JN in mechanical ventilation. Combining lower inspiratory flow and prolonged expiratory time increased respiratory tract deposition with VMN under the investigated experimental conditions. Further studies are required to determine whether these findings translate into clinical benefit.

Aerosol therapy in mechanically ventilated patients is common in intensive care units but lacks standardized practices and clinical evidence. Aerosol deposition depends on nebulizer type, ventilation mode, circuit position, and patient characteristics. This study examined how ventilation mode and nebulization technology affect regional aerosol deposition using a validated ex vivo porcine model. Four experimental conditions compared two nebulization technologies - vibrating mesh nebulizer (VMN) and jet nebulizer (JN) - during two ventilation modes: spontaneous ventilation with pressure support and volume-controlled ventilation. Radiolabeled tracer (99mTc-DTPA) quantified regional aerosol deposition throughout the ventilator circuit and respiratory tract via scintigraphic imaging. Each experiment was repeated three times using different porcine airways ventilated in a hypobaric chamber. Particle size analysis determined Mean Mass Aerosol Diameter (MMAD) and Geometric Standard Deviation. VMN produced significantly higher nebulized fractions (97-98%) versus JN (30-32%). Pulmonary deposition was consistently higher with VMN: 47% versus 9% for JN during spontaneous ventilation, and 57% versus 13% during volume-controlled ventilation. Nebulization technology affected deposition more than ventilation mode. Central-to-total lung deposition ratio was higher for VMN in volume-controlled mode. VMN produced larger particles (MMAD 4.6 mu m) than JN (MMAD 3.7 mu m) with similar dispersion profiles. This regional deposition comparison study demonstrates VMN significantly increased lung deposition up to fivefold, primarily through lower residual doses and higher aerosol output. No significant difference existed between ventilation modes, though volume-controlled ventilation trended higher. Results strongly support using VMN over JN in intensive care units as the key factor for optimizing aerosol delivery.

Aerosol delivery during invasive mechanical ventilation is influenced by multiple factors, including nebulizer type and ventilatory settings. Current intensive care unit (ICU) guidelines generally discourage modifying these parameters due to limited and conflicting evidence. This study evaluated the effects of inspiratory flow and inspiratory-to-expiratory (I:E) ratio on pulmonary aerosol deposition according to nebulizer technology using a controlled preclinical model.Using a validated ex vivo porcine respiratory model under volume-controlled ventilation, we assessed the impact of inspiratory flow (35 vs. 60 L/min) and I:E ratio (1:2 vs. 1:3) on regional aerosol deposition. Experiments were performed with a vibrating mesh nebulizer (VMN) and a jet nebulizer (JN) placed 15 cm upstream of the Y-piece, with active heated humidification. Deposition was measured by planar scintigraphy with radiolabeled aerosol and a mass balance approach.VMN showed significantly higher delivery efficiency than JN in all conditions. With VMN, lower inspiratory flow increased pulmonary deposition (57% ± 8% vs. 45% ± 5%, p = 0.022), and a longer expiratory phase (I:E 1:3 vs. 1:2) further improved deposition (60% ± 9% vs. 45% ± 5%, p < 0.0001), with reduced losses in the inspiratory limb. In contrast, JN had low output and no significant variation across settings.Ventilatory parameters significantly influence aerosol deposition with VMN but not JN in mechanical ventilation. Combining lower inspiratory flow and longer expiratory time may optimize delivery with VMN. These findings support a device-specific approach and require clinical confirmation.

Metal–organic frameworks (MOFs) are porous hybrid materials increasingly used in environmental and biomedical applications. However, their structural diversity and tunable properties complicate the prediction of their biological safety. This study investigated the relationship between physicochemical properties and biological responses of nine representative MOFs based on aluminium, zirconium, zinc and copper clusters (Al-fum, activated Al-fum, MIL-160, UiO-66, UiO-66-NH₂, MIP-202, MOF-801, ZIF-8 and HKUST-1). MOFs were characterized by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), inductively coupled plasma mass spectrometry (ICP-MS) and dynamic light scattering (DLS). Their biological effects were evaluated in RAW264.7 macrophages by assessing membrane integrity (LDH release) and pro-inflammatory cytokine production (TNF-α). The investigated MOFs displayed distinct physicochemical profiles and biological responses, demonstrating that toxicity was not solely determined by metal composition. ZIF-8 exhibited the highest cytotoxicity, whereas zirconium-based MOFs showed the lowest cytotoxic and inflammatory responses. Conversely, MIL-160 induced marked TNF-α production despite limited membrane damage, indicating that inflammatory activation may occur independently of overt cytotoxicity. Overall, these findings establish structure–toxicity relationships linking physicochemical properties to biological responses and support the Safe-and-Sustainable-by-Design development of MOFs.

This study investigates how multiple washing cycles affect the biocide content and performance of reusable biocidal masks, in comparison with type IIR surgical masks. Quantification of copper (Cu) and silver (Ag) biocides was performed using ICP-MS after 0, 1, 5 and 40 wash cycles. The performance of the masks was evaluated by bacterial filtration efficiency (BFE), differential pressure (breathability) and bactericidal activity. Microscopic analyzes were performed to evaluate the evolution of fiber and pore structure. Cu and Ag levels dropped sharply after the first wash and then stabilized. Despite this loss, bactericidal activity remained high after 5 min of contact (87% as new vs. 79% after 40 washes), suggesting that only a minimal residual amount of biocide is required to ensure efficacy. The BFE of the biocidal masks increased with the number of washes (from 71.8% to 88.4%), while the type IIR surgical masks maintained a BFE of 99.9%. Breathability remained within the EN14683 regulatory limit under all conditions. Microscopy showed no significant deterioration in fiber diameter or pore structure, suggesting that washing slightly densifies the textile and improves filtration without compromising the airflow and breathability of the mask. The investigated biocidal masks retain their high bactericidal activity and improve their BFE despite a significant reduction in biocidal content after repeated washing. These results emphasize the importance of textile structure and biocide content for overall performance and support the use of such reusable biocidal masks as a potential sustainable alternative to disposable type IIR surgical masks, even if the filtration properties decrease slightly.

Administration of pulmonary surfactant is crucial for the treatment of respiratory distress syndrome (RDS) in preterm infants. The aim of this study is to evaluate the potential of Curosurf atomization via the Endosurf device, a recently developed spray technology, as a promising approach for surfactant delivery in infants with RDS. A comprehensive analysis was performed to evaluate the physicochemical properties of atomized Curosurf, including its surface tension and rheology. The size distribution of Curosurf vesicles was also investigated. An ex vivo respiratory model based on rabbit lungs breathing through an instrumented hypobaric chamber representing the thorax of a preterm infant was developed to provide proof of concept for regional aerosol deposition of atomized Curosurf. The atomization of Curosurf with the innovative Endosurf device did not significantly alter surface tension, but reduced vesicle size and promoted homogeneous distribution of Curosurf in the lungs. Rheological measurements showed the viscoelastic complexity of atomized Curosurf. This preliminary study confirmed the promising potential of Curosurf atomization via the Endosurf device for the distribution of surfactant in the lungs of infants with RDS. These advances could help to improve the treatment of RDS in preterm infants and offer new perspectives for healthcare professionals and affected families.

The administration of exogenous surfactant is essential for many premature infants to compensate for pulmonary immaturity and the absence of endogenous surfactant at birth. Exogenous surfactant delivery techniques are continually being refined to improve the management of these infants, with the goal of increasing therapeutic efficacy and decreasing the invasiveness of delivery protocols. Imaging is one of the tools available to achieve these goals. In this study, we established and applied an magnetic resonance imaging (MRI) protocol in a rabbit animal model to determine the intrapulmonary distribution of surfactant solution administered by the clinical reference method. The protocol was applied to an ex vivo model of isolated thorax from non-valued food industry by-products. The protocol made it possible to image surfactant biodistribution with isotropic spatial resolution in the millimeter range, to determine surfactant distribution between the main airways and distal lung regions where alveoli are present using automated segmentation techniques, and to quantitatively map the distribution of the administered surfactant solution.

Nanoparticles-based gene delivery has emerged as a promising approach for the treatment of genetic diseases based on efficient delivery systems for therapeutic nucleic acids (NAs) into the target cells. For pulmonary diseases such as cystic fibrosis (CF), chronic obstructive pulmonary diseases (COPD), infectious disease or lung cancer, aerosol delivery is the best choice to locally deliver NAs into the lungs. It is, therefore, important to investigate the effects of nebulization conditions on the efficiency of delivery. To this purpose, the non-viral vector branched polyethyleneimine (b-PEI, 25 kDa) was investigated for plasmid delivery by aerosol. Two types of nebulizers, jet nebulizer and mesh nebulizer, were compared regarding the properties of the nanoparticles (NPs) formed, the efficiency of NAs delivery in vitro and in vivo models and the pulmonary deposition. The results indicate that the mesh nebulizer has a better gene delivery performance than the jet nebulizer in this application. This superiority was demonstrated in terms of size, concentration, distribution of NPs and efficiency of NAs delivery. However, pulmonary deposition appears to be similar regardless of the nebulizer used, and the difference between the two systems lies in the inhalable dose. These results underline the crucial role of nebulization techniques in optimizing aerosol-mediated gene delivery by b-PEI and highlight the potential of mesh nebulizers as promising tools to improved gene therapy. Therefore, the comparison must be performed for each gene therapy formulation to determine the most suitable nebulizer.

Abstract. An inter-laboratory comparison (ILC) involving optical particle counters (OPCs) was organized at the French national level. The aim of this study was to make an inventory of the metrological capabilities of particle number size distribution (PNSD) measurements using OPCs. This laboratory study took place over a period of 18 months and involved 16 partners and 35 OPCs. Rather than focusing on the actual capability of the tested OPCs, this paper aims to reveal good laboratory practices when using standard OPCs. For that, each partner applied the same pre-defined experimental protocol on the OPC(s) to be tested, operated together with a common control OPC. Three different powder-borne test aerosols were involved, and their PNSDs were measured: (1) – a monodisperse amorphous silica sample, (2) – glass beads and (3) – a green cornstarch powder. This article presents the measured PNSD using the 35 OPCs associated with the description of the experimental set-up, sample preparation protocol and comparison with Scanning Electron Microscopy measurements.

This study focuses on research in the area of "nanomaterials in waste" and shows the difficulty of providing quantitative data on nanomaterials in different wastes. As highlighted in the ECHA report (November 2021) and although substantial progress have been made in the characterization and measurement of nanomaterials, some challenges remain, particularly the characterization of nanomaterials in complex media. Therefore, work to improve the detection, characterization, and quantification of nanomaterials should be continued to complete the database with different types of nanowaste mixtures. The dominant end-of-life scenario for nanocomposites is the incineration. The environmental by-products impact on the soil and air have been considered from the point of view of nanoparticles partitioning and the potential toxicological synergistic effects. A specific management of nanocomposites end-of-life should be implemented as recommended by the Organization for Economic Co-operation and Development (OECD) in order to limit nanoparticles dissemination by landfilling and particularly in incineration facilities where their presence is significantly increasing. The aim of our study was to expand the current knowledge of the partition of nanowaste, mainly in case of nanocomposites mixture, and the potential synergetic or antagonistic impact of potential hazardous nanowastes on the toxicological profile. Incineration products of ethylene-vinyl acetate copolymer (EVA) and polydimethylsiloxane (PDMS) nanocomposites containing both silica and precipitated calcium carbonate, corresponding to cable sheaths compositions, were investigated in this study, using a lab-scale incineration process. Soot and residue composition were analysed using various relevant experimental techniques in order to assess the presence of initial nanoparticles. In vitro toxicological assessments were carried out and have shown that only pro-inflammatory responses seem to be affected by the presence of nanoparticles. SiO2 nanoparticles appear to have a major impact on toxicity whatever the partitioning in soot or residue. Conversely, CaCO3 as expected does not impact the nanowaste toxicity and does not seem able to mitigate the SiO2 toxicity.

Transferring the production of nanoparticles from laboratory batches to large-scale production for preclinical and clinical applications represents a challenge due to difficulties in scaling up formulations and lack of suitable preclinical models for testing. Here, we transpose the production of hyaluronic acid and polyarginine-based nanoparticles encapsulating the platinum-derivative dichloro(1,2 diaminocyclohexane)platinum(II), from conventional bulk method to continuous production using microfluidics. The microfluidic-based drug delivery system is then tested in a customised preclinical setup to assess its suitability for pressurised intraperitoneal aerosol chemotherapy (PIPAC), a locoregional chemotherapy used to treat peritoneal carcinomatosis. PIPAC consists of the aerosolization of drugs under pressure using laparoscopy. In our preclinical setup, two clinical aerosol devices, CapnoPen® and TOPOL®, are used in conjunction with syringe pump to achieve the clinically optimal aerosol droplet size range (25-50 μm). Aerosol droplet sizes of 38 and 64 μm are obtained at upstream pressures of 14.7 and 7.4 bar and flow rates of 0.4 and 1.1 mL/s, for CapnoPen® and TOPOL®, respectively. To study the spatial distribution of the aerosol, our preclinical setup is then coupled to an ex-vivo model (inverted porcine urinary bladder) that mimics the physiological peritoneal cavity environment. The smaller droplet size obtained with CapnoPen® provided more homogeneous aerosol distribution in the bladder cavity, crucial for maximising treatment coverage within the peritoneal cavity. Furthermore, stability studies reveal that nanoparticles maintained their physicochemical properties and anticancer activity post-aerosolization. Overall, this study provides a scalable approach for the production of platinum-derivative-loaded polymeric nanoparticles and demonstrates the suitability of this DDS for PIPAC.

Araucaria heterophylla (Ah) and Commiphora pedunculata (Cp) are plant exudate gums from the flora of Benin composed mainly of carbohydrate polymers and a considerable amount of essential oils. The aim of this work is to evaluate the functional properties of these polysaccharide extracts such as the ability to coacervation and cross-linking with gelatin, in order to formulate polymeric materials as microcapsules for essential oils produced exclusively from local resources without toxic products. Their physicochemical and chemical characterics were analysed. The polysaccharide extracts of Ah and Cp plants are water-soluble, amorphous, thermally stable polymers (Td ≈ 300°C) with a number-average molar mass of 21300 and 362600 g.mol-1. The composition of the monosaccharide was determined by HPLC after acid hydrolysis. Galactose, arabinose, rhamnose and glucuronic acid are present in both plants. Galactose is predominant in Ah, while arabinose dominates in Cp. Their aqueous solutions, with mass fractions between 0.5 and 1 %, are slightly acidic and surface-active. At 25°C, in a range of higher concentrations (10-60 %), their aqueous solutions are shear thinning. The presence of glucuronic acid gives the polysaccharides in aqueous solution sufficiently stable negative charges (ζ= -17.0±2.4 mV) to behave like an anionic polymer. These properties allow microencapsulation of the essential oils by complex coacervation between extracted polysaccharides and gelatin for an antioxidant and antibacterial activity. In addition, the polysaccharides were oxidized to be used as crosslinkers for gelatin and their non-cytotoxicity was demonstrated. This work closely follows the guidelines of green chemistry and contributes to a circular economy.

The Covid-19 crisis has led to a massive surge in the use of surgical masks worldwide, causing risks of shortages and high pollution. Reusing the masks may be promising to reduce such risks, especially since various decontamination techniques are being investigated. In this study, the thermal degradation of surgical masks was investigated using X-ray-based techniques such as XRD and XPS. Additional characterization was performed using scanning electron microscopy and contact angle measurements. XRD experiments reveal an increase in both crystal size and crystallinity of the mask with temperature until it is destroyed at 160 degrees C. However, XPS results show that there was no significant change in the surface chemistry of the mask, as no other chemical element has been detected in the mask heated up. Breathability has been proven compliant with standards until 150 degrees C. This study explores the thermal degradation of surgical masks. Utilizing X-ray techniques such as XRD and XPS, alongside scanning electron microscopy and contact angle measurements, we observe an increase in crystal size and crystallinity until the mask's destruction at 160 degrees C. Despite thermal stress, surface chemistry remains unchanged according to XPS analysis. Breathability complies with standards up to 150 degrees C, suggesting potential for mask reuse. image

Background Electronic cigarettes (EC) have gained popularity, especially among young people, with the introduction of fourth-generation devices based on e-liquids containing nicotine salts that promise a smoother vaping experience than freebase nicotine. However, the toxicological effects of nicotine salts are still largely unknown, and the chemical diversity of e-liquids limits the comparison between different studies to determine the contribution of each compound to the cytotoxicity of EC aerosols. Therefore, the aim of this study was to evaluate the toxicological profile of controlled composition e-liquid aerosols to accurately determine the effects of each ingredient based on exposure at the air-liquid interface. Methods Human lung epithelial cells (A549) were exposed to undiluted aerosols of controlled composition e-liquids containing various ratios of propylene glycol (PG)/vegetable glycerin (VG) solvents, freebase nicotine, organic acids, nicotine salts, and flavoured commercial e-liquids. Exposure of 20 puffs was performed at the air-liquid interface following a standard vaping regimen. Toxicological outcomes, including cytotoxicity, inflammation, and oxidative stress, were assessed 24 h after exposure. Results PG/VG aerosols elicited a strong cytotoxic response characterised by a 50% decrease in cell viability and a 200% increase in lactate dehydrogenase (LDH) production, but had no effects on inflammation and oxidative stress. These effects occurred only at a ratio of 70/30 PG/VG, suggesting that PG is the major contributor to aerosol cytotoxicity. Both freebase nicotine and organic acids had no greater effect on cell viability and LDH release than at a 70/30 PG/VG ratio, but significantly increased inflammation and oxidative stress. Interestingly, the protonated form of nicotine in salt showed a stronger proinflammatory effect than the freebase nicotine form, while benzoic acid-based nicotine salts also induced significant oxidative stress. Flavoured commercial e-liquids was found to be cytotoxic at a threshold dose of ≈ 330 µg/cm². Conclusion Our results showed that aerosols of e-liquids consisting only of PG/VG solvents can cause severe cytotoxicity depending on the concentration of PG, while nicotine salts elicit a stronger pro-inflammatory response than freebase nicotine. Overall, aerosols from fourth-generation devices can cause different toxicological effects, the nature of which depends on the chemical composition of the e-liquid.

Background/Objectives: This study focuses on the ability of vaping technology to deliver beclomethasone dipropionate compared to nebulization. Methods: An in vitro comparison of aerosol properties in terms of respirable dose with the Glass Twin Impinger and the mass median aerodynamic diameter using the Next Generation Impactor was performed. The respirable dose delivered in a vaping drug delivery system (VDDS) puff as a function of concentration was quantified by high-pressure liquid chromatography coupled with an ultraviolet detector. Results: The mass of drug contained in a single puff of 55 mL of aerosol varied between 0.94 and 1.95 µg for a refill liquid concentration range of 400 to 1600 µg/mL. The analysis of the particle size distribution shows an advantage for a VDDS in producing smaller particles compared to nebulization (1.56 ± 0.05 µm vs. 2.30 ± 0.19 µm). In total, 81 puffs are needed to reach the dose equivalent to nebulized beclomethasone dipropionate under these specific experimental conditions, which corresponds to an aerosol duration of about 4 min (i.e., four times lower than the jet nebulizer) and a patient administration time of about 45 min (i.e., three times higher than the jet nebulizer). Conclusions: The results show the potential of vaping devices as an alternative to nebulizers for the administration of beclomethasone dipropionate in an equivalent respirable dose.

To investigate potential correlations between human exposure to inhaled particles and pathological effects, the biological monitoring of nanoparticles in broncho-alveolar lavages (BAL) from patients has been proposed. To better understand the underlying mechanisms of toxicity, we propose to couple this biomonitoring of nanoparticles to their in vitro toxicity assessment. However, BAL obtained from regular clinical practice are conditioned with sodium hypochlorite solution (in a 50% v/v ratio), which is toxic to cells. The aim of this study was to develop a protocol to neutralize sodium hypochlorite, allowing to properly investigate the toxicity of the nanoparticles BAL contain. We first tried to neutralize chemically the sodium hypochlorite using H2O2, ascorbic acid or sodium ascorbate but this approach was unsuccessful. In addition, standard toxicology assays (MTT, LDH) could not be used because of interference with neutralizing solutions. We thus changed strategy and used ultracentrifugation to isolate nanoparticles from the sodium hypochlorite solution, with satisfactory extraction yields (88 to 100%). We then incubated the extracted nanoparticles with macrophages from the RAW264.7 cell line and assessed the cell viability and pro-inflammatory response. This study can be used as a proof-of-concept for further study of the biological impact of nanoparticles. This approach paves the way for studies aiming at a better understanding of the aetiology of some idiopathic diseases and underlying mechanisms.

The aim of this study was to quantify the number of non-airborne bacteria that can passively penetrate the layers of four mask types (surgical mask, community face mask type 1 (CFM1), biocidal CFM1 and CFM2) and to determine the influence of wearing conditions for the surgical type. A mask wearer simulator consisting of a 3D anatomical replica of the upper airway connected to a breathing pump was used. Wearing time, filtration quality of the mask, fit (loose vs. tight) and breathing parameters (tidal volume, respiratory rate) were tested. A Staphylococcus epidermidis inoculum was applied to the inner layer. After the wearing simulation, the layers were separated and the bacteria counted. After four hours, no or only a few bacteria were present in the middle and outer layers. Most remained in the inner layer. Surgical mask and CFM1 retained more bacteria and provided a breeding ground for germs. The biocidal CFM1 rapidly reduced the number in the inner layer. The breathing parameters had no influence, in contrast to fit and wearing time. These results confirm that the standard test for bacterial filtration efficiency, which includes the active penetration of airborne bacteria into aerosol droplets, is the most objective measure of the ability of bacteria to penetrate through the mask layers, as the passive penetration ability of non-airborne bacteria is insignificant.