Toxicological effects of micro/nano-plastics on mouse/rat models: a systematic review and meta-analysis.

Micro/nano-plastics (MNPs) are considered a heterogeneous class of environmental contaminants that cause multiple toxic effects on biological species. As the commonly used mammalian models to study the effects of MNPs with regard to their toxic effects, the mouse and rat models are making a great contribution to the disciplines of environmental toxicology and medical health. However, the toxic effects of MNPs have not been systematically summarized. Therefore, a systematic review and a meta-analysis of the toxic effects of MNPs on mouse/rat models were conducted. A total of seven main categories were established in this systematic review, and 24 subcategories were further divided according to the specific physiological significance of the endpoint or the classification of the physiological system, which covered all the selected pieces of literature. A total of 1,762 biological endpoints were found, and 52.78% of them were significantly affected. This fact indicates that there are relative factors, including the size, polymer type, concentration, and exposure time of MNPs and different sexes of mouse/rat models that could significantly affect the biological endpoints. These biological endpoints can be classified into various factors, such as the dose-response relationships between MNP concentration and physiological categories of the nervous system, growth, reproduction, digestive tract histopathology, and inflammatory cytokine level, among others. MNPs negatively affected the blood glucose metabolism, lipid metabolism, and reproductive function in mice. The reproductive function in male mice is more sensitive to the toxic effects of MNPs. These findings also provide insights into and directions for exploring the evidence and mechanisms of the toxic effects of MNPs on human health. It is clear that more research is required on the pathological mechanisms at the molecular level and the long-term effects of tissue accumulation.

The effect of care transition pathway implementation on patients undergoing joint replacement during the COVID-19 pandemic: a quasi-experimental study from a tertiary care hospital orthopedic department in Beijing, China.

BACKGROUND: The coronavirus disease (COVID-19) pandemic has had a massive impact on individuals globally. The Chinese government has formulated effective response measures, and medical personnel have been actively responding to challenges associated with the epidemic prevention and control strategies. This study aimed to evaluate the effect of the implementation of a care transition pathway on patients that underwent joint replacement during the COVID-19 pandemic. METHODS: A quasi-experimental study was designed to evaluate the effect of implementing a care transition pathway for patients who underwent joint replacement during the COVID-19 pandemic in the orthopedic department of a tertiary care hospital in Beijing, China. Using a convenient sampling method, a total of 96 patients were selected. Of these, 51 patients who had undergone joint replacement in 2019 and received treatment via the routine nursing path were included in the control group. The remaining 45 patients who underwent joint replacement during the COVID-19 epidemic in 2020 and received therapy via the care transition pathway due to the implementation of epidemic prevention and control measures were included in the observation group. The quality of care transition was assessed by the Care Transition Measure (CTM), and patients were followed up 1 week after discharge. RESULTS: The observation group was determined to have better general self-care preparation, written planning materials, doctor-patient communication, health monitoring, and quality of care transition than the control group. CONCLUSIONS: A care transition pathway was developed to provide patients with care while transitioning through periods of treatment. It improved the patient perceptions of nursing quality. The COVID-19 pandemic is a huge challenge for health professionals, but we have the ability to improve features of workflows to provide the best possible patient care.

Carboxylation as an effective approach to improve the adsorption performance of graphene materials for Cu2+ removal.

Graphene materials are high-performance adsorbents for water and soil remediation, whose oxygen containing groups bind to metal ions intensely. In this study, we prepared carboxylated graphene oxide (GO-OCH2COOH) sponge and investigated the adsorption behaviors of Cu2+ on it by both experimental and computational approaches. Carboxylation largely improved the adsorption capacity from 23.8mg/g for graphene oxide (GO) sponge to 93.8mg/g for GO-OCH2COOH. The efficient adsorption was due to the strong interaction between Cu2+ and carboxyl groups (especially in -OCH2COOH form) according to the density functional theory calculation, while epoxy and hydroxyl groups contributed lowly. The fast adsorption process was achieved within 30min, corresponding to a large k2 value of pseudo-second order model (0.061mg/g/min). The adsorption was spontaneous and exothermic according to thermodynamics analyses. The binding strength of Cu2+ on GO-OCH2COOH was so strong that pH and ionic strength had mild impact. The strong binding sites were not recyclable, but the weaker ones (more than 40%) could be regenerated by simple washing. Our results highlighted the importance of chemical design in graphene adsorbents and the potential of GO-OCH2COOH in heavy metal fixation from water and soil.

Toxicity of carbon nanotubes to white rot fungus Phanerochaete chrysosporium.

Carbon nanotubes (CNTs) are widely used in diverse areas with increasing annual production, thus the environmental impact of CNTs needs thorough investigation. In this study, we evaluated the effect of pristine multi-walled CNTs (p-MWCNTs) and oxidized multi-walled CNTs (o-MWCNTs) on white rot fungus Phanerochaete chrysosporium, which is the decomposer in carbon cycle and also has many applications in environmental remediation. Both p-MWCNTs and o-MWCNTs had no influence on the dry weight increase of P. chrysosporium and the pH value of culture system. The fibrous structure of P. chrysosporium was disturbed by p-MWCNTs seriously, while o-MWCNTs had litter influence. The ultrastructural changes were more evident for P. chrysosporium exposed to p-MWCNTs and only p-MWCNTs could penetrate into the cell plasma. The chemical composition of P. chrysosporium was nearly unchanged according to the infrared spectra. The laccase activity was suppressed by p-MWCNTs, while o-MWCNTs showed stimulating effect. The decoloration of reactive brilliant red X-3B was not affected by both CNT samples. However, serious inhibition of wood degradation was observed in the p-MWCNTs exposed groups, suggesting the potential threat of CNTs to the decomposition of carbon cycle. The implication to the environmental risks and safe applications of carbon nanomaterials is discussed.

Influence of reduced graphene oxide on the growth, structure and decomposition activity of white-rot fungus Phanerochaete chrysosporium.

Graphene materials have attracted great interest nowadays due to their large-scale production and wide applications. It is urgent to evaluate the ecological and environmental risk of graphene materials for the healthy development of the graphene industry. Herein, we evaluated the influence of reduced graphene oxide (RGO) on the growth, structure and decomposition activity of white-rot fungus, whose decomposition function is vital for carbon cycle. RGO slightly stimulated the fresh weight and dry weight gains of Phanerochaete chrysosporium. A larger number of fibrous structures were observed at low RGO concentrations in P. chrysosporium, which was consistent with the elongation of cells observed under a transmission electron microscope. RGO did not affect the chemical composition of P. chrysosporium. Moreover, the laccase production of P. chrysosporium was not influenced by RGO. The degradation activities of P. chrysosporium for dye and wood appeared to be promoted slightly, but the differences were insignificant compared to the control. Therefore, RGO had low toxicity to white-rot fungus and was relatively safe for the carbon cycle.

Influence of graphene oxide and reduced graphene oxide on the activity and conformation of lysozyme.

The dramatically different bio-effects of graphene and graphene oxide (GO) have been widely observed in diverse biological systems, which determine the applications and toxicity of graphene materials. To elucidate the mechanism at molecular level, it is urgent to investigate the enzyme-graphene interaction and its consequences. In this study, we comparatively studied the influence of GO and reduced GO (RGO) on the activity and conformation of lysozyme to provide better understandings of their different bio-effects. Both GO and RGO adsorbed large quantities of lysozyme after incubation. GO inhibited lysozyme activity seriously, while RGO nearly had no influence on the enzyme activity. The different inhibitions of enzyme activity could be explained by the lysozyme conformational changes, where GO induced more changes to the protein conformation according to UV-vis absorbance, far-UV circular dichroism spectra, intrinsic fluorescence quenching, and infrared spectra. Based on the spectroscopic changes of lysozyme, GO induced the loss of secondary structure and exposed the active site of lysozyme more to the aqueous environment. In addition, neither GO nor RGO induced the fibrillation of lysozyme after 12d incubation. The results collectively indicated that the oxidation degree significantly impacted the enzyme-graphene interaction. The implications to the designs of enzyme-graphene system for bio-related applications and the toxicological effects of graphene materials are discussed.

Surface modification-mediated biodistribution of ¹³C-fullerene C60 in vivo.

BACKGROUND: Functionalization is believed to have a considerable impact on the biodistribution of fullerene in vivo. However, a direct comparison of differently functionalized fullerenes is required to prove the hypothesis. The purpose of this study was to investigate the influences of surface modification on the biodistribution of fullerene following its exposure via several routs of administration. METHODS: (13)C skeleton-labeled fullerene C60 ((13)C-C60) was functionalized with carboxyl groups ((13)C-C60-COOH) or hydroxyl groups ((13)C-C60-OH). Male ICR mice (~25 g) were exposed to a single dose of 400 µg of (13)C-C60-COOH or (13)C-C60-OH in 200 µL of aqueous 0.9% NaCl solution by three different exposure pathways, including tail vein injection, gavage and intraperitoneal exposure. Tissue samples, including blood, heart, liver, spleen, stomach, kidneys, lungs, brain, large intestine, small intestine, muscle, bone and skin were subsequently collected, dissected, homogenized, lyophilized, and analyzed by isotope ratio mass spectrometry. RESULTS: The liver, bone, muscle and skin were found to be the major target organs for C60-COOH and C60-OH after their intravenous injection, whereas unmodified C60 was mainly found in the liver, spleen and lung. The total uptakes in liver and spleen followed the order: C60 > > C60-COOH > C60-OH. The distribution rate over 24 h followed the order: C60 > C60-OH > C60-COOH. C60-COOH and C60-OH were both cleared from the body at 7 d post exposure. C60-COOH was absorbed in the gastrointestinal tract following gavage exposure and distributed into the heart, liver, spleen, stomach, lungs, intestine and bone tissues. The translocation of C60-OH was more widespread than that of C60-COOH after intraperitoneal injection. CONCLUSIONS: The surface modification of fullerene C60 led to a decreased in its accumulation level and distribution rate, as well as altering its target organs. These results therefore demonstrate that the chemical functionalization of fullerene had a significant impact on its translocation and biodistribution properties. Further surface modifications could therefore be used to reduce the toxicity of C60 and improve its biocompatibility, which would be beneficial for biomedical applications.

Toxicity of graphene oxide to white rot fungus Phanerochaete chrysosporium.

With the wide production and applications of graphene and its derivatives, their toxicity to the environment has received much attention nowadays. In this study, we investigated the toxicity of graphene oxide (GO) to white rot fungus (Phanerochaete chrysosporium). GO was prepared by modified Hummers method and well characterized before use. P. chrysosporium was exposed to GO at the concentrations of 0-4 mg/mL for 7 d. The fresh and dry weights, pH values of culture media, structures, ultrastructures, IR spectra and activities of the decomposition of pollutants were measured to reveal the hazards of GO to P. chrysosporium. Our results indicated that low concentrations of GO stimulated the growth of P. chrysosporium. The exposure to GO induced more acidic pH values of the culture media after 7 d. GO induced the disruption of the fiber structure of P. chrysosporium, while at 4 mg/mL some very long and thick fibers were formed. Such changes were reflected in the scanning electron microscopy investigations, where the disruption of fibers was observed. In the ultrastructural investigations, the shape of P. chrysosporium cells changed and more vesicles were found upon the exposure to GO. The infrared spectroscopy analyses suggested that the chemical compositions of mycelia were not changed qualitatively. Beyond the toxicity, GO did not alter the activities of P. chrysosporium at low concentrations, but led to the complete loss of activity at high concentrations. The implication to the ecological safety of graphene is discussed.