Preparation of surface molecularly imprinted polymers with Fe3O4/ZIF-8 as carrier for detection of Dimethoate in cabbage.

In this study, molecularly imprinted polymers (MIPs) were prepared for the specific recognition of organophosphorus pesticides and a rapid, efficient and simple method was established for the detection of dimethoate (DIT) in food samples. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation, and Fe3O4/ZIF-8 complexes were prepared by a modified in-situ polymerization method, and then magnetic molecularly imprinted polymers (MMIPs) were prepared and synthetic route was optimized by applying density functional theory (DFT). The morphological characterization showed that the MMIPs were coarse porous spheres with an average particle size of 50 nm. The synthesized materials are highly selective for the organophosphorus pesticide dimethoate with an adsorption capacity of 461.50 mg·g-1 and are effective resistance to matrix effects. A novel method for the determination of DIT in cabbage was developed using the prepared MMIPs in combination with HPLC. The practical results showed that the method can meet the requirements for the determination of DIT in cabbage with recoveries of 85.6-121.1 % and detection limits of 0.033 µg·kg-1.

Allelochemicals of Alexandrium tamarense and its algicidal mechanism for Prorocentrum donghaiense and Heterosigma akashiwo.

The effects of culture filtrate of Alexandrium tamarense on Prorocentrum donghaiense and Heterosigma akashiwo were investigated, including determination of algal density, photosynthesis, intracellular enzyme content and activity. The filtrate of A. tamarense had a stronger inhibitory effect on P. donghaiense than H. akashiwo, and the inhibitory effect decreased with higher temperature treatment of the filtrate. Instantaneous fluorescence (Ft) and maximum quantum yield of photosystem II (Fv/Fm) values of both kinds of target algae were reduced as exposed to the filtrate of A. tamarense, which proved that allelopathy could inhibit the normal operation of photosynthetic system. The increase of Malondialdehyde (MDA) content of the two kinds of target algae indicated that the cell membrane was seriously damaged by allelochemicals released by A. tamarense. The different responses of Superoxide Dismutase (SOD) and Catalase (CAT) activity in two kinds of target algae demonstrated the complexity and diversity of allelopathic mechanism. The filtrate of A. tamarense also influenced the metabolic function (ATPases) of P. donghaiense and H. akashiwo, and the influence on P. donghaiense was greater. Liquid-liquid extraction was used to extract and isolate allelochemicals from the filtrate of A. tamarense. It was found that only component I with molecular weight of 424.2573 and 434.2857 could inhibit the growth of P. donghaiense by HPLC-MS.

Comparison and evaluation of overcoring and hydraulic fracturing stress measurements.

The stress measurements determined by both the overcoring (OC) and hydraulic fracturing (HF) methods in the Shuichang iron mine and Sanshandao gold mine were compared and evaluated, respectively. The results indicate that the independent OC and HF data in the two mines reveal the same dominant faulting stress regime. The σH orientations derived from the OC and HF methods in the Shuichang iron mine are dominantly oriented in the N81.1°W-N89.4°W and N77.0°E-N88.0°E, respectively, and the σH orientations yielded from the OC and HF techniques in the Sanshandao gold mine are predominantly in the N30°W-N90°W and N55.5°W-N60.4°W, respectively; hence, the σH orientations obtained by the two different methods in the two mines are comparatively similar. In addition, the shapes of the probability density diagrams using an improved Bayesian regression approach of the three principal stresses measured by the OC and HF methods in the same mine are quite similar, and all the obtained Kolmogorov-Smirnov test p-values are larger than the selected significance level of 0.01, indicating that the stress data interpreted by the two methods approximately follow the same distribution law. Thus, the performance of the two techniques and the reliability of the measured data are satisfactory.

Effect of butylphthalide on prevention and treatment of high altitude cerebral edema in rats.

3-n-butylphthalide (NBP) contains one of the main active ingredients of celery seed. It has a series of pharmacological mechanisms, including reconstitution of microcirculation, protection of mitochondrial function, inhibition of oxidative stress, and inhibition of neuronal apoptosis. Based on the complex multi-targeting of NBP pharmacological mechanisms, the clinical applications of NBP are increasing, and more and more clinical studies and animal experiments have focused on NBP. In this study, we used male Sprague Dawley rats as an animal model to elucidate the intervention effect of butylphthalide on high altitude cerebral edema (HACE), and also compared the effect of butylphthalide and rhodiola rosea on HACE. Firstly, we measured the changes of body weight and brain water content and observed the pathological changes of brain tissues. In addition, the contents of inflammatory factors, oxidative stress and brain neurotransmitters were assessed by enzyme-linked immunoassay kits, and finally, the expression of apoptotic proteins in brain tissues was determined by western blotting. The results showed that NBP reduced brain water content, attenuated brain tissue damage, altered inflammatory factors, oxidative stress indicators, and brain neurotransmitter levels, and in addition NBP inhibited the expression of Caspase-related apoptotic proteins. Therefore, NBP has the potential to treat and prevent HACE.

Single and combined toxic effects of nCu and nSiO2 on Dunaliella salina.

There are many studies on the toxic effects of single nanoparticles on microalgae; however, many types of nanoparticles are present in the ocean, and more studies on the combined toxic effects of multiple nanoparticles on microalgae are needed. The single and combined toxic effects of nCu and nSiO2 on Dunaliella salina were investigated through changes in instantaneous fluorescence rate (Ft) and antioxidant parameters during 96-h growth inhibition tests. It was found that the toxic effect of nCu on D. salina was greater than that of nSiO2, and both showed time and were dose-dependent with the greatest growth inhibition at 96 h. A total of 0.5 mg/L nCu somewhat promoted the growth of microalgae, but 4.5 and 5.5 mg/L nCu showed negative growth effects on microalgae. The Ft of D. salina was also inhibited by increasing concentrations of nanoparticles and exposure time. nCu suppressed the synthesis of TP and elevated the MDA content of D. salina, which indicated the lipid peroxidation of algal cells. The activities of SOD and CAT showed a trend of increasing and then decreasing with the increase of nCu concentration, suggesting that the enzyme activity first increased and then decreased. The toxic effect of a high concentration of nCu was reduced after the addition of nSiO2. SEM and EDS images showed that nSiO2 could adsorb nCu in seawater. nSiO2 also adsorbed Cu2+ in the cultures, thus reducing the toxic effect of nCu on D. salina to a certain extent. TEM image was used to observe the morphology of algal cells exposed to nCu.

Predictive Value and Immunological Role of the HSPA5 Gene in Cervical Cancer.

Cervical cancer (CC) ranks fourth among women's malignancies worldwide and seriously affects women's health. HSPA5 is a heat shock protein, also known as glucose regulatory protein 78 (GRP78). Upregulation of HSPA5 has been reported to be closely associated with multiple types of tumors. However, the specific role of HSPA5 in cervical cancer has not been discovered. In our study, we explored the prognostic value of HSPA5 in CC. Here, we analyzed the (TCGA) and (UCSC) databases, the analysis of HSPA5 in many tumors types was conducted with the "wilcox. test" method. A False Discovery Rate (FDR) value < 0.05 and Log2 | (fold change, FC) |> 1 were set as the cutoffs. "*", "**", and "***" indicate FDR < 0.05, < 0.01, and < 0.001, respectively, and further used human cervical cancer cells for q-PCR and western blotting detection. q-PCR and western blotting results showed that HSPA5 was highly expressed in cervical cancer cells, while it was expressed at low levels in normal cells (P < 0.05).We also analyzed the immunohistochemical data. immunohistochemical analysis results showed that HSPA5 was highly expressed in human cervical cancer, while it was expressed at low levels in normal tissues (P < 0.05). Analysis in TCGA-UCSC showed that the proportion of G3 in the group with high expression of HSPA5 was relatively high (P < 0.05). Enrichment analysis and survival analysis showed that the increased expression of HSPA5 in cervical cancer was related to the survival of CC and was involved in the regulation of biological behavior and molecular signaling pathways of cervical cancer. The correlation analysis of immune checkpoint and immune infiltration showed that HSPA5 was involved in the regulation of immune process of cervical cancer (P < 0.05). Drug sensitivity correlation analysis showed that HSPA5 was a sensitive target for tumor drugs (P < 0.05). In brief, those results suggest that HSPA5 can act as an oncogene of CC development and can serve as an effective predictive biomarker in cervical cancer.

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.

Pyrolysis of exhausted biochar sorbent: Fates of cadmium and generation of products.

Biochar is a promising sorbent for Cd removal from water, while the disposal of the exhausted Cd-enriched biochar remains a challenge. In this study, pyrolysis was employed to treat the exhausted biochar under N2 and CO2 atmospheres at 600-900 °C, and the fate of Cd during pyrolysis and characteristics of high-valued products were determined. The results indicated that higher temperature and CO2 atmosphere favored the volatilization of Cd. Based on the toxicity characteristic leaching procedure (TCLP) results, the pyrolysis treatment under both atmospheres enhanced the stability of Cd, and the leached Cd concentration of regenerated biochar obtained at high temperatures (>800 °C) was lower than 1 mg/L. Compared with the pristine biochar, the regenerated biochar demonstrated higher carbon content and pH, whereas the contents of oxygen and hydrogen declined, and exhibited promising sorption properties (35.79 mg/g). The atmosphere played an important role in modifying biochar properties and syngas composition. The N2 atmosphere facilitated CH4 production, whereas the CO2 atmosphere increased the proportion of CO. These results implied that pyrolysis can be a valuable and environmental-friendly strategy for the treatment and reuse of exhausted biochar sorbent.

The effect of N-methyl-D-aspartate receptor antagonists on the mismatch negativity of event-related potentials and its regulatory factors: A systematic review and meta-analysis.

This study investigates the influence of N-methyl-D-aspartate receptor (NMDAR) antagonists on the mismatch negativity (MMN) components of event-related potentials (ERPs) in healthy subjects and explores whether NMDAR antagonists have different effects on MMN components under different types of antagonists, drug dosages, and deviant stimuli. We conducted a comprehensive literature search of PubMed, EMBASE, and the Cochrane Library from inception to August 1, 2023 for studies comparing the MMN components between the NMDAR antagonist intervention group and the control group (or baseline). All statistical analyses were performed using Stata version 12.0 software. Sixteen articles were included in the systematic review: 13 articles were included in the meta-analysis of MMN amplitudes, and seven articles were included in the meta-analysis of MMN latencies. The pooled analysis showed that NMDAR antagonists reduced MMN amplitudes [SMD (95% CI) = 0.32 (0.16, 0.47), P < 0.01, I2 = 47.3%, p < 0.01] and prolonged MMN latencies [SMD (95% CI) = 0.31 (0.13, 0.49), P = 0.16, I2 = 28.3%, p < 0.01]. The type of antagonist drug regulates the effect of NMDAR antagonists on MMN amplitudes. Different antagonists, doses of antagonists, and types of deviant stimuli can also have different effects on MMN. These findings indicate a correlation between NMDAR and MMN, which may provide a foundation for the application of ERP-MMN in the early identification of NMDAR encephalitis.

Optimal sequence of LT for symptomatic BM in EGFR-mutant NSCLC: a comparative study of first-line EGFR-TKIs with/without upfront LT.

BACKGROUND: The third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) can penetrate blood-brain barrier and are effective for brain metastases (BMs). There is no consensus on the optimal sequence of local therapy (LT) and EGFR-TKIs for symptomatic BM patients because patients suffering neurological symptoms were not enrolled in most clinical trials. METHODS: Non-small cell lung cancer (NSCLC) patients with EGFR mutation (EGFRm) and symptomatic BM receiving first-line osimertinib and aumolertinib from two medical centers were collected. All participants were allocated into the third-generation EGFR-TKIs (TKIs) group and the upfront LT (uLT) plus third-generation EGFR-TKIs (TKIs + uLT) group. Demographic data, survival outcomes, treatment failure patterns, and adverse events were evaluated between the two groups. We also conducted subgroup analyses to explore the impact of BM number on survival outcomes. RESULTS: 86 patients were enrolled, 44 in the TKIs group and 42 in the TKIs + uLT group. There were no significant differences in the short-term response between the groups. TKIs + uLT was associated with significantly longer overall survival (OS) (43 vs. 28 months; hazard ratio [HR], 0.36, 95% confidence interval [CI], 0.17-0.77; p = .011). No differences in progression-free survival (PFS), intracranial PFS (iPFS), failure patterns, or safety were observed. In subgroup analyses of oligo-BM patients, TKIs + uLT could prolong OS (43 vs. 31 months; HR 0.22; 95% CI 0.05-0.92; p = .015). CONCLUSIONS: EGFRm NSCLC patients with symptomatic BM might benefit from uLT, particularly oligo-BM patients. However, larger prospective cohort studies should be carried out to confirm the responses of the TKIs + uLT scheme.

Immune cell early activation, apoptotic kinetic, and T-cell functional impairment in domestic pigs after ASFV CADC_HN09 strain infection.

African swine fever (ASF) caused by the African swine fever virus (ASFV) is a fatal and highly contagious disease of domestic pigs characterized by rapid disease progression and death within 2 weeks. How the immune cells respond to acute ASFV infection and contribute to the immunopathogenesis of ASFV has not been completely understood. In this study, we examined the activation, apoptosis, and functional changes of distinct immune cells in domestic pigs following acute infection with the ASFV CADC_HN09 strain using multicolor flow cytometry. We found that ASFV infection induced broad apoptosis of DCs, monocytes, neutrophils, and lymphocytes in the peripheral blood of pigs over time. The expression of MHC class II molecule (SLA-DR/DQ) on monocytes and conventional DCs as well as CD21 expression on B cells were downregulated after ASFV infection, implying a potential impairment of antigen presentation and humoral response. Further examination of CD69 and ex vivo expression of IFN-γ on immune cells showed that T cells were transiently activated and expressed IFN-γ as early as 5 days post-infection. However, the capability of T cells to produce cytokines was significantly impaired in the infected pigs when stimulated with mitogen. These results suggest that the adaptive cellular immunity to ASFV might be initiated but later overridden by ASFV-induced immunosuppression. Our study clarified the cell types that were affected by ASFV infection and contributed to lymphopenia, improving our understanding of the immunopathogenesis of ASFV.

Geometric remodeling of tricuspid valve in pulmonary hypertension and its correlation with pulmonary hypertension severity: a prospectively case-control study using four-dimensional automatic tricuspid valve quantification technology.

Background: Evaluation of the tricuspid valve (TV) is crucial for clinical decision making and post-treatment follow-up in pulmonary hypertension (PH) patients. However, little is known about 4-dimensional (4D) TV geometric remodeling in patients with PH. The aim of this study was to examine the 4D geometry of the TV in PH and its correlation with PH severity. Methods: A total of 74 PH patients with mean pulmonary arterial pressure >25 mmHg and 15 age- and gender-matched healthy individuals were consecutively included from September 2017 to December 2018 in National Center for Cardiovascular Diseases, Fuwai Hospital. All participants underwent 2-dimensional (2D) and 4D transthoracic echocardiography and PH patients underwent right heart catheterization (RHC) within 48 hours of echocardiography. TV geometry was analyzed using a dedicated 4D echocardiography from the right ventricular-focused apical view. Results: Compared with controls, PH patients had significantly larger 4D tricuspid annular (TA) and TV tenting sizes except in the 2-chamber diameter. In high-quality image cases, maximal tenting height (MTH), coaptation point height, tenting volume and 4-chamber diameter had good or moderate correlation with PH severity graded according to RHC mean pulmonary artery pressure (r=0.705, r=0.644, r=0.602, r=0.472, respectively; P<0.001 for all). In multivariable linear regression analysis, PH severity was independently associated with coaptation point height (F=18.070, P<0.001 with an R2=0.647) and MTH (F=25.576, P<0.001 with an R2=0.378). Among all 4D TV parameters, MTH had the highest area under the receiver operating characteristic (ROC) curve (AUC) in high-quality image cases [AUC =0.857, 95% confidence interval (CI): 0.743-0.972; P<0.001], comparable to echocardiographic systolic pulmonary arterial pressure (AUC =0.847, 95% CI: 0.733-0.961; P<0.001). Conclusions: In PH, TV geometric remodeling occurs mainly in TA septal-lateral dimension and TV tenting height. Worsening PH is an independent determinant of TV coaptation point height and MTH, not TA size. MTH shows a great diagnostic potential to detect severe PH.

Clinical relevance of ORCs in predicting prognosis and immunotherapy outcomes: A pan-cancer analysis.

BACKGROUND: The origin recognition complex (ORC) consists of six subunits and mediates DNA replication by binding to its origin. Recent studies show that ORCs are closely related to various biological processes in tumors. However, a comprehensive study of ORCs in pan-cancer has not been conducted. RESULTS: A systematic evaluation of the expression, mutation, and prognostic significance of ORCs was conducted across cancer types using data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. The single-sample Gene Set Enrichment Analysis (ssGSEA) was performed using R package "Gene Set Variation Analysis (GSVA)" to evaluate ORC score. ORC score was significantly elevated in most cancers and linked with an inferior prognosis. It was positively related to the G2/M checkpoint and DNA repair pathways. An elevated ORC score also correlated with tumor mutation burden (TMB)/ microsatellite instability (MSI). A prognosis analysis suggested that high ORC scores were associated with heightened immunotherapeutic sensitivity. CONCLUSIONS: Our research elucidates the genomic changes associated with and clinical relevance of ORCs in cancer and provides unique insights for future investigation of ORCs in immunotherapy.

Uncovering the flip side of immune checkpoint inhibitors: a comprehensive review of immune-related adverse events and predictive biomarkers.

Immune checkpoint inhibitors (ICIs) have generated considerable excitement as a novel class of immunotherapeutic agents due to their remarkable efficacy in treating various types of cancer. However, the widespread use of ICIs has brought about a number of safety concerns, especially the development of immune-related adverse events (irAEs). These serious complications could result in treatment discontinuation and even life-threatening consequences, making it critical to identify high-risk groups and predictive markers of irAEs before initiating therapy. To this end, the current article examines several potential predictive markers of irAEs in important organs affected by ICIs. While retrospective studies have yielded some promising results, limitations such as small sample sizes, variable patient populations, and specific cancer types and ICIs studied make it difficult to generalize the findings. Therefore, prospective cohort studies and real-world investigations are needed to validate the potential of different biomarkers in predicting irAEs risk. Overall, identifying predictive markers of irAEs is a crucial step towards improving patient safety and enhancing the management of irAEs. With ongoing research efforts, it is hoped that more accurate and reliable biomarkers will be identified and incorporated into clinical practice to guide treatment decisions and prevent the development of irAEs in susceptible patients.

Droplet-Based Preparation of ZnO-nanostructure Array for Microfluidic Fluorescence Biodetection.

Nanostructure-enhanced biodetection is widely used for early diagnosis and treatment, which plays an essential role in improving the cure rates of cancer patients. ZnO nanostructure-based fluorescence immunoassay has been demonstrated to enable effective and sensitive detection of cancer biomarkers for their excellent biocompatibility, high electrical point, and unique fluorescence enhancement properties. Further optimization of such fluorescence detection technology is still in demand to meet the requirements of highly sensitive, multiplex detection, and user-friendly devices. Droplet microfluidics is a promising platform for high-throughput analysis of biological assays, and they have been intensively used in analytical chemistry and synthesis of nanoparticles. Here, we propose a simple droplet chip, where a static droplet array was successfully obtained for in situ growth of ZnO nanostructures with varied diameters by changing the entire growth time and replenishment interval. This device provides a novel and alternative approach for patterned growth of ZnO nanostructures and understanding the growth condition of ZnO nanostructures in static droplet, which offers some guidance toward the design of multiple fluorescence amplification platforms potentially for biosensing. As a demonstration, we used the patterned grown ZnO nanostructures for multiple detection of cancer biomarkers, achieving a low limit of detection as low as 138 fg/mL in the human α-fetoprotein assay and 218 fg/mL in the carcinoembryonic antigen assay with a large dynamic range of 8 orders. These results suggest that such multifunctional microfluidic devices may be useful tools for efficient fluorescence diagnostic assays.

Spatiotemporal distribution, source analysis and ecological risk assessment of polychlorinated biphenyls (PCBs) in the Bohai Bay, China.

As a class of persistent organic pollutants (POPs), the spatial and temporal distribution of polychlorinated biphenyls (PCBs) in seawater is important for environmental assessment. Surface water samples were collected from 35 stations during summer and 36 stations during autumn of 2020 in the Bohai Bay. The concentration, composition, distribution and sources of PCBs were analyzed to assess the ecological impact of PCBs. The average concentration of ∑18PCBs was 124.6 ng/L (range of 28.1-445.5 ng/L) in summer and 122.8 ng/L (range of 21.0-581.4 ng/L) in autumn. PCBs in surface seawater of the Bohai Bay showed high near-shore and low far-shore characteristics, indicating the serious influence of land-based sources such as port activities and river inputs. Proportion analysis showed that Tetra-PCBs and Penta-PCBs were the major constituents in most stations. It was assessed as moderate and high risk (MRQ > 0.1) by mixture risk quotient (MRQ) and concentration addition (CA) model in surface seawater of the Bohai Bay. Principal component analysis (PCA) was used to explain the sources of PCBs in the Bohai Bay. PCBs in the Bohai Bay may come from commercial PCBs and their incineration products, municipal landfills, wood and coal combustion, and industrial activities, etc.

Detection of a temporal salient object benefits from visual stimulus-specific adaptation in avian midbrain inhibitory nucleus.

Food and predators are the most noteworthy objects for the basic survival of wild animals, and both are often deviant in both spatial and temporal domains and quickly attract an animal's attention. Although stimulus-specific adaptation (SSA) is considered a potential neural basis of salient sound detection in the temporal domain, related research on visual SSA is limited and its relationship with temporal saliency is uncertain. The avian nucleus isthmi pars magnocellularis (Imc), which is central to midbrain selective attention network, is an ideal site to investigate the neural correlate of visual SSA and detection of a salient object in the time domain. Here, the constant order paradigm was applied to explore the visual SSA in the Imc of pigeons. The results showed that the firing rates of Imc neurons gradually decrease with repetitions of motion in the same direction, but recover when a motion in a deviant direction is presented, implying visual SSA to the direction of a moving object. Furthermore, enhanced response for an object moving in other directions that were not presented ever in the paradigm is also observed. To verify the neural mechanism underlying these phenomena, we introduced a neural computation model involving a recoverable synaptic change with a "center-surround" pattern to reproduce the visual SSA and temporal saliency for the moving object. These results suggest that the Imc produces visual SSA to motion direction, allowing temporal salient object detection, which may facilitate the detection of the sudden appearance of a predator.

Toxic effects of nSiO2 and mPS on diatoms Nitzschia closterium f. minutissima.

To investigate the toxic mechanism of SiO2 nanoparticles (nSiO2) and polystyrene microplastics (mPS) on microalgae Nitzschia closterium f. minutissima, growth inhibition tests were carried out. The growth and biological responses of the algae exposed to nSiO2 (0.5, 1, 2, 5, 10, 30 mg L-1) and mPS (1, 5, 10, 30 and 75 mg L-1) were explored in f/2 media for 96 h. Both micro-/nano-particles (MNPs) inhibited the growth of N. closterium f. minutissima in a concentration- and time-dependent manner. The toxic effect of mPS on N. closterium f. minutissima is higher than that of nSiO2, because silicon is essential for diatoms to maintain cell wall integrity, and the addition of appropriate amounts of nSiO2 can be absorbed and used as a nutrient to promote diatom growth and protect the integrity of the siliceous shell to some extent. Both MNPs induce the production of excess oxidation and activate the cellular antioxidant defense system, leading to increased SOD and CAT activity as a means to resist oxidative damage to the cell, and eliminating excess ROS and maintaining normal cell morphology and metabolism. SEM is consistent with the results of MDA, showing that mPS with high concentrations attach to the surface of algal cells to produce heterogeneous aggregates and disrupt the cell wall and cell membrane, causing the cells to expand and rupture. This study contributes to the understanding of the size effect of MNPs on the growth of marine diatom.

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.