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The unicellular photosynthetic organisms known as microalgae are becoming one of the most important models for aquatic system studies. Among them, Chlamydomonas reinhardtii is widely used as a bioindicator of pollution or of different changes in the environment. Numerous pollutants are present in aquatic environments, particularly plastics and nanoplastics. Physiological variations after an environmental change highlight variation in the macromolecular composition of microalgae (proteins, nucleic acids, lipids and carbohydrates). Recently, Fourier transform infrared vibrational spectroscopy has been described as a reliable tool, sensitive and allowing rapid measurement of macromolecular composition of microalgae. Coupled with preprocessing and principal component analysis, it is well adapted to monitoring the effect of environmental stress on biochemical composition. In this study, infrared spectroscopy, combined with multivariate analysis, has been tested first on known environmental stresses such as light intensity variation and nitrogen limitation. Then, this technique has been applied to monitor the interaction and potential impacts of polystyrene nanoparticles on microalgae. The results showed slight variations on protein and carbohydrates bands in the presence of nanoplastics, suggesting that their presence led to modifications in the biochemical composition of the microalgae. To confirm the interaction between microalgae and nanoplastics, visualization by confocal microscopy and cytotoxicity measurement has been carried out. Results showed that polystyrene nanoparticles seemed to adsorb on microalgae surface, leading to a loss of plasma membrane integrity. The resulting chemical modifications, even if moderate, could be detected by infrared spectroscopy‚ showing that this tool could be very helpful in the understanding of nanoparticle-microalgae interaction mechanisms.

Plastic pollution is a major and global threat to ecosystems and human health, resulting from the spreading and breakdown of plastic litter in the environment. In an aquatic environment, the first causes of this degradation are exposure to natural ultraviolet light and abrasion or collisions in the water. The extent of such degradation on a plastic object after a given time remains very difficult to quantify, especially regarding the relative production of microplastics, nanoplastics and soluble species along with volatile compounds. All of these degradation products may contribute differently to environmental pollution. Therefore, when evaluating the pollution caused by plastic objects, we should consider how much of each byproduct is generated. We propose a novel method based on conservation of the carbon mass during the degradation process. This approach is the first to enable quantification of carbon retrieved in each type of degradation product (Microplastics, Nanoplastics, Solubles, Volatile Compounds), as well as its evolution with exposure time. By applying this method to polypropylene granules, we demonstrate its effectiveness in tracking carbon footprint throughout the aging process. One of the unexpected results of this study is to show that the amount of carbon released in volatile form is far from negligible (17%) compared to MP (55%). The procedure we present is general enough to be applied to any type of polymer, and can be a valuable tool for assessing the amount of by-products of a given size released into the environment.

Marine plastic pollution is a major environmental issue. Given their ubiquitous nature and small dimensions, ingestion of microplastic (MP) and nanoplastic (NP) particles and their subsequent impact on marine life are a growing concern worldwide. Transfers along the trophic chain, including possible translocation, for which the hazards are less understood, are also a major preoccupation. Effects of MP ingestion have been studied on animals through laboratory exposure, showing impacts on feeding activity, reserve depletion and inflammatory responses, with consequences for fitness, notably reproduction. However, most experimental studies have used doses of manufactured virgin microspheres that may not be environmentally realistic. As for most ecotoxicological issues, the environmental relevance of laboratory exposure experiments has recently been debated. Here we review constraints and priorities for conducting experimental exposures of marine wildlife to microplastics based on the literature, feedback from peer reviewers and knowledge gained from our experience. Priorities are suggested taking into account the complexity of microplastics in terms of (i) aggregation status, surface properties and interactions with organic and inorganic materials, (ii) diversity of encountered particles types and concentrations, (iii) particle bioavailability and distribution in experimental tanks to achieve reproducibility and repeatability in estimating effects, and (iv) strict experimental procedures to verify the existence of genuine translocation. Relevant integrative approaches encompass a wide spectrum of methods from -omics to ecophysiological approaches, including modelling, are discussed to provide novel insights on the impacts of MP/NP on marine ecosystems from a long-term perspective. Knowledge obtained in this way would inform stakeholders in such a way as to help them mitigate impacts of the micro- and nano-plastic legacy.

The impact of a microplastic (MPs) mixture composed of polyethylene (PE) and polypropylene (PP) plastic particles, prepared from commercially available products, was evaluated in blue mussels Mytilus spp. exposed to three environmentally relevant concentrations: 0.008µg Lˉ¹ (low), 10 µg Lˉ¹ (medium) and 100 µg Lˉ¹ (high). Organisms were exposed for 10 days followed by 10 days of depuration in clean seawater under controlled laboratory conditions. The evaluation of MP effects on mussel clearance rate, tissue structure, antioxidant defences, immune and digestive parameters, and DNA integrity were investigated while the identification of plastic particles in mussel tissues (gills, digestive gland, and remaining tissues), and biodeposits (faeces and pseudofaeces) was performed using infrared microscopy (µFT-IR). Results showed the presence of MPs only in the digestive gland of mussels exposed to the highest tested concentration of MPs with a mean of 0,75 particle/mussel (after the 10 days of exposure). In biodeposits, PE and PP particles were detected following exposure to all tested concentrations confirming the ingestion of MPs by the organisms. A differential response of antioxidant enzyme activities between digestive gland and gills was observed. Significant increases in superoxide dismutase (SOD) and catalase (CAT) activities were measured in the digestive gland of mussels exposed to the low (0.008µg Lˉ¹) and medium (10 µg Lˉ¹) concentrations of MPs and in the gills from mussels exposed to the highest concentration (100 µg Lˉ¹) of MPs that could be indicative of a change in the redox balance. Moreover, an increase in acid phosphatase activity was measured in hemolymph of mussels exposed to 0.008 and 10 µg Lˉ¹ concentrations. No significant difference was observed in the clearance rate, and histopathological parameters between control and exposed mussels. This study brings new insights on the potential sublethal impacts of MPs at environmentally relevant concentrations in marine bivalves.

Diatoms are feedstock for the production of sustainable biocommodities, including biofuel. The biochemical characterization of newly isolated or genetically modified strains is seminal to identify the strains that display interesting features for both research and industrial applications. Biochemical quantification of organic macromolecules cellular quotas are time-consuming methodologies which often require large amount of biological sample. Vibrational spectroscopy is an essential tool applied in several fields of research. A Fourier transform infrared (FTIR) microscopy-based imaging protocol was developed for the simultaneous cellular quota quantification of lipids, carbohydrates, and proteins of the diatom Phaeodactylum tricornutum . The low amount of sample required for the quantification allows the high throughput quantification on small volume cultures. A proof of concept was performed (1) on nitrogen-starved experimental cultures and (2) on three different P. tricornutum wild-type strains. The results are supported by the observation in situ of lipid droplets by confocal and brightfield microscopy. The results show that major differences exist in the regulation of lipid metabolism between ecotypes of P. tricornutum .

The detection and quantification of micro(nano)plastics in the marine environment are essential requirements to understand the full impacts of plastic pollution on the ecosystem and human health. Here, static light scattering (SLS) and dynamic (DLS) light scattering techniques are assessed for their capacity to detect colloidal particles with diameters between d = 0.1 and 0.8 µm at very low concentrations in seawater. The detection limit of the apparatus was determined using model monodisperse spherical polystyrene latex particles with diameters of 0.2 µm and 0.5 µm. It is shown that the concentration and size of colloids can be determined down to about 10−6 g/L. Light scattering measurements on seawater obtained from different locations in Western Europe show that colloidal particles were detected with DLS in seawater filtered through 0.8 µm pore size filters. The concentration of these particles was not higher than 1 µg/L, with an average diameter of about 0.6 µm. We stress that these particles are not necessarily plastic. No particles were detected after filtration through 0.45 µm pore size filters. La détection et la quantification des micro(nano)plastiques dans le milieu marin sont des exigences essentielles pour comprendre tous les impacts de la pollution plastique sur l’écosystème et la santé humaine. Ici, les techniques de diffusion statique de la lumière (SLS) et dynamique (DLS) sont évaluées pour leur capacité à détecter des particules colloïdales d'un diamètre compris entre d = 0,1 et 0,8 µm à de très faibles concentrations dans l'eau de mer. La limite de détection de l'appareil a été déterminée à l'aide de particules modèles de latex de polystyrène sphériques monodispersées d'un diamètre de 0,2 µm et 0,5 µm. Il est démontré que la concentration et la taille des colloïdes peuvent être déterminées jusqu'à environ 10 −6 g/L. Les mesures de diffusion de la lumière sur l'eau de mer obtenues à différents endroits en Europe occidentale montrent que des particules colloïdales ont été détectées avec DLS dans l'eau de mer filtrée à travers des filtres de taille de pores de 0,8 µm. La concentration de ces particules n’était pas supérieure à 1 µg/L, avec un diamètre moyen d’environ 0,6 µm. Soulignons que ces particules ne sont pas nécessairement du plastique. Aucune particule n'a été détectée après filtration à travers des filtres de taille de pores de 0,45 µm.

Microplastics (MPs) constitute a main environmental issue due to their threat to marine organisms and so far to humans. The lack of a fast standard protocol in MP isolation and identification from living organisms bring to challenge for the science. In this paper, an optimized protocol using potassium hydroxide 10% (KOH 10%; m/v) for digestion of mussel soft tissues ( Mytilus edulis ) and multi-steps of sedimentation has been developed. Efficiency higher than 99.9% of organic and mineral matter elimination was shown by application on mussels sampled on the French Atlantic coast. The identification of MPs was performed by FTIR microscopy straight on the filter and the whole analysis can be compatible with a routine goal. Fourteen MPs of four different chemical natures were found and identified in 5 pools of 3 sampled mussels. Their size ranged from 30 to 200 μm. Further investigations are now needed to evaluate the potential risk of such particles within this marine bivalve species and other filter feeders.

Fast monitoring and control quality of food products become increasingly important for public health. Among foodborne pathogenic microorganisms, bacteria are the most common foodborne pathogens in which the currently used methods are time consuming, labour-intensive and costly. This work aims to develop a new biochip potentially used for an assessment of bacterial contamination on food product. An assessment for bacterial detection employs simple FTIR spectroscopic analysis with a complimentary surface characterization by SEM technique. The biochip based on carboxylic acid functionalized polyurethane (PU) film was synthesized for bacterial detection in particular Salmonella Typhimurium. The PU in this study was synthesized from the reaction of the alcohol groups of hydroxyl telechelic natural rubber based oligomer with the isocyanate groups of 2,4-toluene diisocyanate. The carboxylic acid functional group was incorporated into the PU chain by addition of dimethylol propionic acid as a chain extender during PU preparation. The PU film having different degree of carboxylic acid was explored for the detection of S. Typhimurium. The structural and morphological changes of the PU film after loading of the bacteria were successfully detected using ATR-FTIR and SEM, respectively. The PU film developed is considered a rapid tool for S. Typhimurium detection and has a potential application for rapid food control quality.

Interaction and surface binding characteristics of staphylococcal protein A (SpA) and an anti-Escherichia coli immunoglobulin G (IgG) were studied using the Raman spectroscopy. The tyrosine amino acid residues present in the α-helix structure of SpA were found to be involved in interaction with IgG. In bulk interaction condition the native structure of proteins was almost preserved where interaction-related changes were observed in the overall secondary structure (α-helix) of SpA. In the adsorbed state, the protein structure was largely modified, which allowed the identification of tyrosine amino acids involved in SpA and IgG interaction. This study constitutes a direct Raman spectroscopic investigation of SpA and IgG (receptor-antibody) interaction mechanism in the goal of a future biosensor application for detection of pathogenic microorganisms.

The aim of this study was to synthesize in high product yield of anisotropic core-shell Fe O @Au magnetic nanoparticles and to investigate the effect of the immunomagnetic separation (IMS) volume on the capture efficiency. For these purposes and for the first time, we synthesized polyhedral magnetic nanoparticles composed of Fe O core Au shell. To synthesize magnetic gold anisotropic core-shell particles, the seed-mediated synthetic method was carried out. By choosing an appropriate amount of iron particles and growth solution the fine control of the seed-mediated approach is enabled. This led to the high product yield of anisotropic nanoparticles. The magnetic separation of these nanoparticles was easily accomplished, and the resulting nanoparticles were characterized with transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV–vis), near edge absorption fine structure (NEXAFS) spectroscopy, and X-ray diffraction (XRD). Additionally, the magnetic properties of the nanoparticles were examined. The magnetic nanoparticles (MNPs) were modified with antibody and interacted with ( ). The high capture efficiency between the magnetic nanoparticles and is evidenced by SEM images. The capture efficiency decreases with an increase of volumes, and the highest capture efficiency was observed for in an experiment volume of 100 μL for magnetic nanoparticles. The percentage of captured for polyhedral nanoparticles was found to be approximately 95 % and for spherical nanoparticles 88 %, respectively.