With the increasing integration of nanomaterials into daily life, the potential ecotoxicological impacts of nanoparticles (NPs) have attracted increased attention from the scientific community. This study assessed the ecotoxicity of ZnS quantum dots (QDs) doped with varying molar concentrations of Mn2+ on Chlorella vulgaris. The ZnS:Mn QDs were synthesized using the polyol method. The size of the ZnS:Mn QDs ranged from approximately 1.1 nm to 2 nm, while the aggregation size in Seine River water was 341 nm at pH 6 and 8. The presence of ZnS:Mn (10%) NPs exhibited profound toxicity to Chlorella vulgaris, with immediate reductions in viability (survival cells) from 71%, 60% to 51%, 52% in BG11 and Seine River water, respectively, at a concentration of 100 mg L−1 of ZnS:Mn (10%) NPs. Additionally, the ATP content in Chlorella vulgaris significantly decreased in Seine River water (by 20%) after 3 h of exposure to ZnS:Mn (10%) NPs. Concurrently, SOD activity significantly increased in Seine River water, indicating that the ZnS:Mn (10%) NPs induced ROS production and triggered an oxidative stress response in microalgae cells.

The release of engineered materials into the environment can have detrimental effects on living organisms in ground, rivers, and oceans. Despite the increasing use of nanomaterials, little research is conducted on their degradation. Understanding the biology and environmental consequences of manufactured materials is crucial for preserving the environment and developing more respectful chemistry protocols. Physicochemical studies are essential to understand material behavior and their uptake and distribution within microorganisms. II-VI semiconducting nanocrystals, like ZnS nanoparticles, have emerged due to their quantum confinement, allowing for customization of electronic and optical properties. To assess the toxicity of ZnS QDs doped with Mn2+ and perform ecotoxicological tests, a suitable natural environment and an aquatic model are needed. Microalgae, like Chlorella Vulgaris, offer advantages in ecotoxicology, including environmental relevance, sensitivity, experimental feasibility, ethical considerations, and comparative studies. This paper presents the synthesis of ZnS:Mn NPs with varying concentrations of Mn2+. These NPs induce an antioxidant defense system in algal cells, which may be toxic to Chlorella vulgaris via an oxidative stress mechanism. The toxicity of manganese-doped ZnS nanoparticles does exist but is lower than that induced by a Mn2+ ion concentration of 100 mg L-1.

With the wide use of nanomaterials in our daily life, the potential ecotoxicology effect of nanoparticles (NPs) has attracted more and more attention from researchers. Here, the ZnS:Mn (0.5%, 2.0%, 4.0% and 10% of Mn, in mol) QDs were synthesized using the polyol method, and the toxicity mechanism was investigated by contacting the microalgae Chlorella vulgaris with ZnS:Mn QDs in different culture media (BG11, Seine River water - SRW, synthetic seawater - SSW). The crystalline size of the synthesized QDs was around 1.5 nm, but the particles tended to aggregate since the size of the ZnS:Mn colloids determined by DLS ranged from 300 nm to 700 nm at pH 6 and 8. From a toxicological point of view, all these ZnS:Mn QDs caused a decrease in the photosynthetic activity, cell viability, and intracellular ATP level; moreover, the SOD activity significantly increased in SSW, which evidenced that the ZnS:Mn NPs would expose the algae cell in the oxidative stress environment. Finally, TEM observations of the algae thin sections confirmed the internalization of the ZnS:Mn NPs, which caused the leakage of the cytoplasm.

In this work, a first demonstration of an hydrogel-gated organic field-effect transistor (HGOFET) for the detection of water pollutants is described. Photosynthetic cyanobacteria were entrapped in a hydrogel grafted onto the platinum gate of the transistor. Photosynthesis was continuously monitored by electroreduction of the oxygen produced or consumed by the cyanobacteria on the gate electrode, under illumination or in the dark, respectively. The presence of herbicides such as diuron and glyphosate was found to strongly affect the cyanobacteria's photosynthetic activity, which was transduced into a significant drop of the device's gate current, strongly amplified onto the drain. This study demonstrates the suitability of HGOFETs for environmental monitoring. (C) 2021 Elsevier Ltd. All rights reserved.

Seine river water was used as natural environmental medium to study the ecotoxicological impact of ZnO and CdS nanoparticles and Zn2+ and Cd2+ free ions using Chlorella vulgaris as a biological target. It was demonstrated by viability tests and photosynthetic activity measurements that free Zn2+ (IC50 = 2.7 × 10−4 M) is less toxic than free Cd2+ and ZnO nanoparticles (IC50 = 1.4 × 10−4 M). In the case of cadmium species, free Cd2+ (IC50 = 3.5 × 10−5 M) was similar to CdS nanoparticles (CdS-1: IC50 = 1.9 × 10−5 M and CdS-2: IC50 = 1.9 × 10−5 M), as follows: CdS > Cd2+ > ZnO > Zn2+. Adenosine-5’-triphosphate (ATP) assay and superoxide dismutase (SOD) enzymatic activity confirmed these results. Transmission electron microscopy (TEM), coupled with energy-dispersive X-ray spectroscopy (EDS), confirmed the internalization of CdS-1 nanoparticles after 48 h of contact with Chlorella vulgaris at 10−3 M. With a higher concentration of nanoparticles (10−2 M), ZnO and CdS-2 were also localized inside cells.

Organic electrochemical transistors (OECTs) are now well-known, robust and efficient as amplification devices for redox reactions, typically biologically ones. In contrast, electrolyte-gated organic field-effect transistors (EGOFETs) have never been described for that kind of application because field-effect transistors are known as capacitive coupled devices, i.e., driven by changes in capacitance at the electrolyte/gate or electrolyte/semiconductor interface. For such a kind of transistors, any current flowing at the gate electrode is seen as a drawback. However, we demonstrate in this paper that not only the gate potential can trigger the source-drain current of EGOFETs, which is the generally accepted mode of operation, but that the current flowing at the gate can also be used. Because EGOFETs can work directly in water, and as an example of application, we demonstrate the possibility to monitor microalgae photosynthesis through the direct measurement of photosynthetic O2 production within the transistor’s electrolyte, thanks to its electroreduction on the EGOFET’s gate. This paves the way for the use of EGOFETs for environmental monitoring.

Cellulose nanofibers have mechanical properties that make them very attractive in a myriad of fields such as biomedicine, tissue engineering, biosensors, cosmetics and food packet products. To evaluate the potential health risks of airborne cellulose nanofibers, the cellulose nanofiber was prepared and characterized and then its pulmonary potential toxicity to a mouse model was studied. Cellulose nanofiber has been prepared by acid hydrolysis of cotton cellulose and characterized by transmission electron microscopy, zeta potential and X-ray diffraction analysis. Then, using a short-term inhalation test, the pulmonary biocompatibility of cotton cellulose nanofibers at different concentrations (0.5 mg/mL, 1 mg/mL and 2 mg/mL) were evaluated. Transmission electron images showed needle-shaped particle with a diameter of about 6–18 nm and a length of 85–225 μm. Zeta potential was −25.3±7.80 mV and the X-ray diffraction patterns indicate that cotton cellulose nanofiber has pure structural characteristics. The In Vivo results revealed that the exposure to cotton cellulose nanofiber did not alter the number of inflammatory cells or cytokine secretion by lung cells (p > 0.05). The results demonstrate that the cotton cellulose nanofiber is biocompatible and it is an environment-friendly nanomaterial with promise in various industrial sectors.

Among organic thin film transistors (OTFTs), Organic Electrochemical Transistors (OECTs) have been extensively used for cell monitoring while Electrolyte-Gated Organic Field-Effect Transistors (EGOFETs) have never been described for that kind of application. However, EGOFETs are well adapted for this use because, as well as OECTs, they can operate directly in aqueous solutions such as cells culture media, but they offer much a higher on/off ratio which could lead to better sensitivity. As a proof of concept, we propose herein to monitor the photosynthetic activity of a cyanobacterium (Anabaena flos-aquae) contained within an EGOFET's electrolyte.

New niobium-based oxygen carriers were prepared adopting polyol-mediated process. Four different polyols were used (diethylene glycol, triethylene glycol, tetraethylene glycol, and 1,2-propanediol) and four different quantities of water (0 mL, 1 mL, 10 mL, 30 mL, with a total volume of 80 mL of solution). Series of bulk and alumina-supported materials were prepared. Different structural and textural properties were obtained, depending on polyol type and hydrolysis ratio. After thermal treatment at 1000 °C, alumina-supported materials were evaluated in a lab-scaled fixed bed reactor. Despite a low conversion of methane due to a low content of active phase AlNbO4, they presented a high selectivity to syngas (a mixture of H2 and CO) during the first few seconds of reaction with CH4, indicating a high selectivity towards chemical-looping reforming process.

Understanding the biological processes enabling magnetotactic bacteria to maintain oriented chains of magnetic iron-bearing nanoparticles called magnetosomes is a major challenge. The study aimed to constrain the role of an external applied magnetic field on the alignment of magnetosome chains in Magnetospirillum magneticum AMB-1 magnetotactic bacteria immobilized within a hydrated silica matrix. A deviation of the chain orientation was evidenced, without significant impact on cell viability, which was preserved after the field was turned-off. Transmission electron microscopy showed that the crystallographic orientation of the nanoparticles within the chains were preserved. Off-axis electron holography evidenced that the change in magnetosome orientation was accompanied by a shift from parallel to anti-parallel interactions between individual nanocrystals. The field-induced destructuration of the chain occurs according to two possible mechanisms: (i) each magnetosome responds individually and reorients in the magnetic field direction and/or (ii) short magnetosome chains deviate in the magnetic field direction. This work enlightens the strong dynamic character of the magnetosome assembly and widens the potentialities of magnetotactic bacteria in bionanotechnology.

After about three decades of development, the polyol process is now widely recognized and practised as a unique soft chemical method for the preparation of a large variety of nanoparticles which can be used in important technological fields. It offers many advantages: low cost, ease of use and, very importantly, already proven scalability for industrial applications. Among the different classes of inorganic nanoparticles which can be prepared in liquid polyols, metals were the first reported. This review aims to give a comprehensive account of the strategies used to prepare monometallic nanoparticles and multimetallic materials with tailored size and shape. As regards monometallic materials, while the preparation of noble as well as ferromagnetic metals is now clearly established, the scope of the polyol process has been extended to the preparation of more electropositive metals, such as post-transition metals and semi-metals. The potential of this method is also clearly displayed for the preparation of alloys, intermetallics and core-shell nanostructures with a very large diversity of compositions and architectures.

Phytochelatins or PCn,(gamma Glu-Cys),-Gly,and their glutathione (GSH) precursor are thiol-rich peptides that play an important role in heavy metal detoxification in plants and microorganisms. Complex formation between Cd2+ and Pb2+ and GSH or PCn (n = 2, 4 and 6) are investigated by microcalorimetry, absorption spectrophotometry and T-jump kinetics. Complex formation with Pb2+ or Cd2+ is exothermic, and induces ligand metal charge transfer bands in UV absorption spectral range, which implies the formation of a coordination bond between the metal and the thiol groups of the phytochelatins. Absorption spectra and microcalorimetry experiments allow the determination of the affinity constants and the stoichiometry of the complexes. We show that the three PCn interact with Pb2+ to form the 1:1 and 2:1 M:L complexes, with similar affinity constants (log K-11(pb) similar to 4.6 log K-21(pb)similar to 11.4). These affinities are independent of the number of thiols and are, moreover, lower than those determined for complex formation with Cd2+. On the other hand, with Cd2+, PC2-Cd, PC2-Cd-2, (PC2)(3)-Cd-2, PC4-Cd, PC4-Cd-2, PC6-Cd, (PC6)(2)-Cd-3 and PC6-Cd-3 complexes are detected. Furthermore, for PC4-Cd, the 1:1 complex is the most stable: affinity constant (log K-11(cd)similar to 7.5). Kinetic studies indicate that complex formation between Cd2+ and GSH occurs in the ms range; direct rate constant k(obs) = (6.8 +/- 0.3) 106 M-1 s(-1) and reverse rate constant k(-obs), = 340 +/- 210 s(-1). Thus, when encapsulated in a silica matrix, PCn can be good candidates for heavy metal detection. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

Multi-walled carbon nanotubes (MWCNTs) have potential applications in the industrial, agricultural, pharmaceutical, medical, and environmental remediation fields. However, many uncertainties exist regarding the environmental implications of engineered nanomaterials. This study examined the effect of the MWCNTs on metabolic status and morphology of filamentous green microalgae Klebsormidium flaccidum. Appropriate concentrations of MWCNT (1, 50, and 100 μg mL−1) were added to a microalgal culture in the exponential growth phase and incubated for 24, 48, 72, and 96 h. Exposure to MWCNT led to reductions in algal growth after 48 h and decreased on cell viability for all experimental endpoints except for 1 µg mL−1 at 24 h and 100 µg mL−1 after 72 h. At 100 µg mL−1, MWCNTs induced reactive oxygen species (ROS) production and had an effect on intracellular adenosine triphosphate (ATP) content depending on concentration and time. No photosynthetic activity variation was observed. Observations by scanning transmission electron microscopy showed cell damage. In conclusion, we have demonstrated that exposure to MWCNTs affects cell metabolism and microalgal cell morphology. To our best knowledge, this is the first case in which MWCNTs exhibit adverse effects on filamentous green microalgae K. flaccidum. These results contribute to elucidate the mechanism of MWCNT nanotoxicity in the bioindicator organism of terrestrial and freshwater habitats.

Silicates-in-silica nanocomposite hydrogels obtained from sodium silicates/colloidal silica mixtures have previously been found to be useful for bacterial encapsulation. However the extension of synthesis conditions and the understanding of their impact on the silica matrix would widen the applicability of this process in terms of encapsulated organisms and the host properties. Here the influence of silicates and the colloidal silica concentration as well as pH conditions on the gel time, the optical properties, the structural and mechanical properties of silica matrices was studied. We show that gel formation is driven by silicate condensation but that the aggregation of silica colloids also has a major influence on the transparency and structure of the nanocomposites. Three different photosynthetic organisms, cyanobacteria Anabaena flos-aquae and two microalgae Chorella vulgaris and Euglena gracilis, were used as probes of the phycocompatibility of the process. The three organisms were highly sensitive to the silicate concentration, which impacts both the gelation time and ionic strength conditions. The Ludox content was crucial for cyanobacteria as it strongly impacts the Young's modulus of the matrices. The detrimental effect of acidic pH on cell suspension was compensated by the silica network. Overall, it is now possible to select optimal encapsulation conditions based on the physiology of the targeted cells, opening wide perspectives for the design of biosensors and bioreactors.

Optical biosensors for the detection of toxic species in aqueous media were developed via the encapsulation of microalgae in sol–gel matrices. In a first step, the effect of cadmium(II), lead(II), and anthracene on the chlorophyll a fluorescence intensity of Anabaena flos-aquae, Chlorella vulgaris, and Euglena gracilis microalgae in suspension was studied. Complementary ATP-metry measurements demonstrated a direct relationship between optical response and pollutant toxicity, in a cell- and dose-dependent manner. In a second step, microalgae were successfully encapsulated in silicate–colloidal silica nanocomposite matrices. However, a complete loss of cell response to pollutant addition was observed, despite the preservation of cell viability. Introduction of a low amount (5 mol%) of amine- or ethyl-bearing silanes in the matrix formulation allowed the recovery of the sensing capacity of the immobilized microalgae, without impacting on the response time (30 s). Porosimetry and 29Si solid-state NMR spectroscopy showed that the organic moieties are fully integrated into the inorganic network, tuning the ability of the target pollutant to diffuse and reach the encapsulated algae. This versatile strategy could be useful for the easy and fast assessment of contamination levels in polluted waters.

Recent years have witnessed a boom in the biosynthesis of a large variety of nanomaterials using different biological resources among which algae-based entities have been gaining much more attention within the community of material scientists worldwide. In our previously published findings, we explored some factors that governed the biofabrication of gold nanoparticles using living cultures of microalgae, such as the utilized microalgal genera, the phylum they belong to, and the impact of tetrachloroauric acid concentrations on the ability of these strains to perform the biosynthesis of gold nanoparticles once in contact with these cations. As a follow-up, we present in this paper an improvement of the features of bioproduced gold colloids using living cells of Euglena gracilis microalga when this species is grown under either mixotrophic or autotrophic conditions, i.e., exposed to light and grown in an organic carbon-enriched culture medium versus under autotrophic conditions. As an outcome to this alteration, the growth rate of this photosynthetic microorganism is multiplied 7–8 times when grown under mixotrophic conditions compared to autotrophic ones. Therefore, the yield, the kinetics, and the colloidal stability of the biosynthesized gold nanoparticles are dramatically enhanced. Moreover, the shape and the size of the as-produced nano-objects via this biological method are affected. In addition to round-shaped gold nanoparticles, particular shapes, such as triangles and hexagons, appear. These findings add up to the amassed knowledge toward the design of photobioreactors for the scalable and sustainable production of interesting nanomaterials.

Recently, cellulose nanofibers (CNFs) have attracted considerable attention as natural, abundant polymers with excellent mechanical properties and biodegradability. CNFs provide a new materials platform for the sustainable production of high-performance nano-enable products for various applications. Given the increasing rates of CNF production, the potential for their release to the environment and the subsequent impact on ecosystem is becoming an increasing concern that needs to be addressed. Here, we used the Klebsormidium flaccidum as a bioindicator organism of terrestrial and freshwater habitats pollution using a battery of biomarkers. Our results show that cotton CNFs inhibit the proliferation of algae and induce morphological changes in them. The two main toxicity mechanisms induced by cotton CNFs are: (i) a direct contact of CNFs with the cell wall and cellular membrane and (ii) an indirect effect through the generation of reactive oxygen species (ROS).

Studies have been demonstrating that smaller particles can lead to unexpected and diverse ecotoxicological effects when compared to those caused by the bulk material. In this study, the chemical composition, size and shape, state of dispersion, and surface’s charge, area and physicochemistry of micro (BT MP) and nano barium titanate (BT NP) were determined. Green algae Chlorella vulgaris grown in Bold’s Basal (BB) medium or Seine River water (SRW) was used as biological indicator to assess their aquatic toxicology. Responses such as growth inhibition, cell viability, superoxide dismutase (SOD) activity, adenosine-5-triphosphate (ATP) content and photosynthetic activity were evaluated. Tetragonal BT (~170 nm, 3.24 m2 g−1 surface area) and cubic BT (~60 nm, 16.60 m2 g−1) particles were negative, poorly dispersed, and readily aggregated. BT has a statistically significant effect on C. vulgaris growth since the lower concentration tested (1 ppm), what seems to be mediated by induced oxidative stress caused by the particles (increased SOD activity and decreased photosynthetic efficiency and intracellular ATP content). The toxic effects were more pronounced when the algae was grown in SRW. Size does not seem to be an issue influencing the toxicity in BT particles toxicity since micro- and nano-particles produced significant effects on algae growth.

As an alternative approach to the well known Ca(II)-alginate encapsulation process within silica hydrogels, proton-driven alginate gelation was investigated in order to establish its capacity as a culture carrier, both isolated and embedded in an inorganic matrix. Control over the velocity of the proton-gelation front allows the formation of a hydrogel shell while the core remains liquid, allowing bacteria and microalgae to survive the strongly acidic encapsulation process. Once inside the inorganic host, synthesized by a sol-gel process, the capsules spontaneously redissolve without the aid of external complexing agents. The entrapped cells survive the two-step process to a significant extent; culture's growth restores the initial cell count in less than two weeks. Biosynthesis of Au nanoparticles mediated by the entrapped microalgae illustrates the preservation of the biosynthetic abilities supported by this platform.