Molecularly imprinted ratiometric fluorescence sensor for visual detection of 17ß-estradiol in milk: A generalized strategy toward imprinted ratiometric fluorescence construction.

17ß-Estradiol (E2) is the typical endocrine disruptor of steroidal estrogens and is widely used in animal husbandry and dairy processing. In the environment, even lower concentrations of E2 can cause endocrine dysfunction in organisms. Herein, we have developed a novel molecularly imprinted ratiometric fluorescent sensor based on SiO2-coated CdTe quantum dots (CdTe@SiO2) and 7-hydroxycoumarin with a post-imprint mixing strategy. The sensor selectively detected E2 in aqueous environments due to its two fluorescent signals with a self-correction function. The sensor has been successfully used for spiking a wide range of real water and milk samples. The results showed that the sensor exhibited good linearity over the concentration range 0.011-50 µg/L, obtaining satisfactory recoveries of 92.4-110.6% with precisions (RSD) < 2.5%. Moreover, this sensor obtained an ultra-low detection limit of 3.3 ng/L and a higher imprinting factor of 13.66. By using estriol (E3), as a supporting model, it was confirmed that a simple and economical ratiometric fluorescent construction strategy was provided for other hydrophobic substances.

Effects of polystyrene nanoplastics on growth and hemolysin production of microalgae Karlodinium veneficum.

There are few studies on the effects of nanoplastics on growth and hemolysin production of harmful algal bloom species at present. In this study, Karlodinium veneficum was exposed to different concentrations (0, 5, 25, 50, 75 mg/L) of polystyrene nanoplastics (PS-NPs, 100 nm) for 96 h. The effects of PS-NPs on growth of K. veneficum were investigated by measuring algal cell abundance, growth inhibition rate (IR), total protein (TP), malondialdehyde (MDA), glutathione reductase (GSH), superoxide dismutase (SOD), ATPase activity (Na+/K+ ATPase and Ca2+/Mg2+ ATPase). Scanning electron microscope and transmission electron microscope (SEM and TEM) images of microalgae with or without nanoplastics were also observed. The effects of PS-NPs on hemolysin production of K. veneficum were studied by measuring the changes of hemolytic toxin production of K. veneficum exposed to PS-NPs on 1, 3, 5 and 7 days. High concentrations (50 and 75 mg/L) of PS-NPs seriously affected the growth of K. veneficum and different degrees of damage to cell morphology and ultrastructure were found. Excessive free radicals and other oxidants were produced in the cells, which disrupted the intracellular redox balance state and caused oxidative damage to the cells, and the basic activities such as photosynthesis and energy metabolism were weakened. The athletic ability of K. veneficum was decreased, but the ability to produce hemolysin was enhanced. It was suggested that the presence of nanoplastics in seawater may strengthen the threat of harmful algal bloom species to aquatic ecosystems and human health.

Assessing the potential risks, sources and the relationship between the dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) in the typical semi-enclosed bay, Bohai Bay of China.

This study aimed to investigate the spatial and temporal distribution as well as the partitioning behavior of dissolved and particulate polycyclic aromatic hydrocarbons (PAHs) during the summer and autumn seasons of 2020. It was found that the average concentration of PAHs in surface seawater was significantly higher in autumn (58.16 ng L-1) than in summer (40.47 ng L-1) due to a large amount of input in autumn and more photodegradation and biodegradation affected by higher temperatures in summer. The spatial distribution indicated that the river had a significant dilution effect on PAHs in summer and became a significant input source in autumn. In addition, a large number of oil and gas development platforms were distributed throughout the Bohai Bay, and the discharge of production and domestic sewage contributed to the PAHs pollution level. As a semi-enclosed bay, the water exchange capacity of Bohai Bay was poor, leading to a greater accumulation of PAHs in the marine environment. The diagnostic ratios and PCA-MLR indicated that petroleum was the most important source of PAHs with a contribution of 45%, followed by fuel combustion (39%) such as coal and oil. Photooxidation in seawater resulted in a reduction of BaP/BeP, indicating that seasonal variations in photooxidation had a significant impact on the composition of PAHs (summer: 1.49, autumn: 2.96). The concentration of particulate PAHs was correlated with the concentration of dissolved PAHs and SPM, and the proportion of 3-rings (43.8%) and 4-rings (49.8%) PAHs was significantly higher on SPM. The distribution coefficients Log Kd and φspm-water showed a trend of increasing and then decreasing as the number of rings increased, with the 4-rings Pyr exhibiting the highest value. According to the ecological risk assessment, the ecological risk of total PAHs was low (RQNCs < 800, RQMECs < 1), but the ecological risk of individual PAHs and the carcinogenicity of high-ring PAHs could not be ignored (＞96.5%). This study is significant for investigating the "sources and sinks" of PAHs in the complex marine environment by analyzing the partitioning behavior of PAHs in different phases.

Energy metabolism response induced by microplastic for marine dinoflagellate Karenia mikimotoi.

Microplastic contaminations threaten the entire marine ecosystem and cause severe ecological stress. This study explored the energy metabolism change of Karenia mikimotoi under exposure to nanoplastics (NPs) and microplastics (MPs) (65 nm, 100 nm, and 1 µm polystyrene (PS), and 100 nm polymethyl methacrylate (PMMA)) at a concentration of 10 mg L-1. Membrane potential, esterase activity, polysaccharide content, and ATPase activity were detected to assess the energy metabolism of K. mikimotoi under MPs/NPs exposure. Transcriptome and metabolomic analyses were used to investigate the intrinsic mechanisms of energy metabolism changes. Smaller PS particles caused greater damage to the cell membrane potential, increased the polysaccharide content, and resulted in a heavier weakening of the ATPase enzymatic activity in K. mikimotoi cells, suggesting that smaller-sized PS had more influence on esterase activity and energy metabolism than the bigger-sized PS. The results evidenced that energy metabolism relates to the size and type of MPs/NPs, and nano-scale plastic particles could induce greater metabolic changes.

Is hydrodynamic diameter the decisive factor? - Comparison of the toxic mechanism of nSiO2 and mPS on marine microalgae Heterosigma akashiwo.

To investigate the toxic mechanism of SiO2 nanoparticles (nSiO2) and polystyrene microplastics (mPS) on microalgae Heterosigma akashiwo, growth inhibition tests were carried out. The growth and biological responses of the algae exposed to nSiO2 (0.5, 1, 1.5, 2, 5, 10 and 30 mg L-1) and mPS (1, 2, 5, 10, 30 and 75 mg L-1) were explored in f/2 media for 96 h. It was found that the hydrodynamic diameter of the particles seems to be one of the more important factors to influence the algae. nSiO2 and mPS with similar hydrodynamic diameters have the similar toxic mechanism on H. akashiwo, and the effects were dose- and time-dependent. High concentrations of micro-/nano-particles (MNPs) could inhibit the growth of algal cells, however, low concentrations of MNPs did not restrict or even promoted the growth of algae, known as "Hormesis" phenomenon. The 96 h-EC20 values of nSiO2 and mPS on H. akashiwo were 2.69 and 10.07 mg L-1, respectively, and chlorophyll fluorescence parameters indicated that the microalgal photosynthetic system were inhibited. The hydrophilic surface of nSiO2 increased the likelihood of nSiO2 binding to the hydrophilic functional group of microalgae, which may account for the slightly stronger toxic effect of nSiO2 than mPS. The algae continued to produce reactive oxygen species (ROS) under stress conditions. Total protein (TP) levels reduced, and superoxide dismutase (SOD) and catalase (CAT) levels increased to maintain ROS levels in the cells. The decrease in adenosine triphosphate (ATPase) indicated an impact on cellular energy metabolism. Cell membrane damage, cytoplasm and organelle efflux under stress were confirmed by scanning and transmission electron microscopy (SEM and TEM) images. This study contributes to the understanding of the size effect of MNPs on the growth of marine microalgae.

Highly selective separation and detection of cyromazine from seawater using graphene oxide based molecularly imprinted solid-phase extraction.

A novel molecularly imprinted polymer based on graphene oxide was prepared as a solid-phase extraction adsorbent for the selective adsorption and extraction of cyromazine from seawater samples. The obtained graphene oxide molecularly imprinted polymer and non-imprinted polymer were nanoparticles and characterized by scanning electron microscopy. The imprinted polymer showed higher adsorption capacity and better selectivity than non-imprinted polymer, and the maximum adsorption capacity was 14.5 mg/g. The optimal washing and elution solvents for molecularly imprinted solid phase extraction procedure were 2 mL of acetonitrile/water (80:20, v/v) and methanol/acetic acid (70:30, v/v), respectively. The recoveries of cyromazine in the spiked seawater samples were in the range of 90.3-104.1%, and the relative standard deviation was <5% (n = 3) under the optimal procedure and detection conditions. The limit of detection of the proposed method was 0.7 µg/L, and the limit of quantitation was 2.3 µg/L. Moreover, the imprinted polymer could keep high adsorption capacity for cyromazine after being reused six times at least. Finally, the synthesized graphene oxide molecularly imprinted polymer was successfully used as a satisfied sorbent for high selectivity separation and detection of cyromazine from seawater coupled with high-performance liquid chromatography.

The interactions between micro polyvinyl chloride (mPVC) and marine dinoflagellate Karenia mikimotoi: The inhibition of growth, chlorophyll and photosynthetic efficiency.

Microplastics pose a great threat to entire marine ecosystems, but little is known about their impacts on phytoplankton, especially for the harmful dinoflagellates. In this study, effects of micro polyvinyl chloride (mPVC) on the growth, chlorophyll content and photosynthetic efficiency of the dinoflagellate Karenia mikimotoi at different periods (0, 24, 48, 72 and 96 h) were assessed using gradient concentrations (0, 5, 25, 50 and 100 mg L-1) of mPVC with a size of 1 µm. PVC microplastics had dose-dependent adverse effects on K. mikimotoi growth, chlorophyll content and photosynthetic efficiency. The density of algal cell decreased with increasing mPVC concentrations and the highest inhibitory rate (IR) was 45.8% at 24 h under 100 mg L-1 of mPVC. The total chlorophyll content and chlorophyll content in a single algal cell decreased at 96 h and the ФPSⅡ and Fv/Fm decreased 25.3% and 17.1%, respectively. The SEM images provided an intuitive visual method to observe the behaviors and interactions between microplastics and microalgae. It was found from the SEM images that microalgae was wrapped by microplastic beads. The physical blockage and aggregation were also responsible for the cytotoxicity of K. mikimotoi. Our study clarified that PVC microplastics can reduce algal growth, chlorophyll content and photosynthetic efficiency, and it is beneficial to evaluate the possible impact of plastics on aquatic ecosystems.

Toxic effects of microplastic on marine microalgae Skeletonema costatum: Interactions between microplastic and algae.

To investigate toxic effects of microplastic on marine microalgae Skeletonema costatum, both algal growth inhibition test and non-contact shading test were carried out, and algal photosynthesis parameters were also determined. The SEM images were used to observe interactions between microplastic and algae. It was found that microplastic (mPVC, average diameter 1 µm) had obvious inhibition on growth of microalgae and the maximum growth inhibition ratio (IR) reached up to 39.7% after 96 h exposure. However, plastic debris (bPVC, average diameter 1 mm) had no effects on growth of microalgae. High concentration (50 mg/L) mPVC also had negative effects on algal photosynthesis since both chlorophyll content and photosynthetic efficiency (ΦPSⅡ) decreased under mPVC treatments. Shading effect was not one reason for toxicity of microplastic on algae in this study. Compared with non-contact shading effect, interactions between microplastic and microalage such as adsorption and aggregation were more reasonable explanations for toxic effects of microplastic on marine microalgae. The SEM images provided a more direct and reasonable method to observe the behaviors of microplastic.

Preparation and characterization of magnetic molecularly imprinted polymers for selective trace extraction of dienestrol in seawater.

Highly selective and efficient magnetic molecularly imprinted polymers (MMIPs) were prepared using Fe3O4@SiO2 as a magnetic supporter, 3-methacryloxypropyltrimethoxy-silane (MPS) as a silane coupling agent, DIS as a template, methacrylic acid (MAA) as a functional monomer and ethyleneglycol dimethacrylate (EGDMA) as a cross-linker for the extraction of trace residuals of the synthetic estrogen dienestrol (DIS) in seawater, which is a concern worldwide for its endocrine disruption and carcinogenic danger to human health. The obtained MMIPs were demonstrated to have spherical morphologies, core-shell structures, large binding capacities, high efficiency and selectivity. These were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and adsorption experiments. Owing to the specific binding sites, the MMIPs exhibited an almost three times higher adsorption capacity towards DIS (Qmax=4.68mgg-1) than magnetic molecularly non-imprinted polymers (MNIPs) (Qmax=1.72mgg-1). DIS in spiked seawater samples from the Weihai Bay of China was extracted and enriched by MMIPs, and satisfactory recoveries (87.3%-96.4%) with low relative standard deviation (RSD) values (2.03%-5.18%, n=5) were obtained. The limit of detection (LOD) of the method obtained was 0.16µgL-1, and the limit of quantitation was 0.52µgL-1 after MMIPs. No significant deterioration of the adsorption capacity of the MMIPs was observed after six rounds of regeneration. The results further demonstrated the applicability of the MMIPs method, a simple and straightforward method for the extraction and enrichment of DIS in seawater without any time-consuming procedures.