Sorption of polyhalogenated carbazoles (PHCs) to microplastics.

The sorption of 5 Polyhalogenated carbazoles (PHCs) [3,6-dibromocarbazole (3,6-BCZ), 3,6-dichlorocarbazole (3,6-CCZ), 3,6-diiodocarbazole (3,6-ICZ), 2,7-dibromocarbazole (2,7-BCZ) and 3-bromocarbazole (3-BCZ)] on to three microplastics [polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC)] in a simulated seawater system are studied. Sorption isotherms demonstrated that PVC had the maximum sorption capacity, which can be attributed to polar-polar interaction. The sorption kinetics model showed that the sorption process was controlled by both intraparticle and film diffusion. The sorption of PHCs to microplastics was significantly influenced by temperature, the sorption capacity first increased gradually and then decreased with the increasing temperature. Increasing the salinity decreased the sorption of PHCs onto PP, PE, PVC microplastics. Our results indicated that all three kinds of microplastics can serve as carriers for PHCs in the aquatic environment, which put marine ecosystems at higher risks.

Sorption of 3,6-dibromocarbazole and 1,3,6,8-tetrabromocarbazole by microplastics.

Microplastics and organic pollutants are typical contaminants in the marine environment. However, little is known about their interactions. In this study, the sorption of 3,6-Dibromocarbazole(3,6-BCZ) and 1,3,6,8-Tetrabromocarbazole (1,3,6,8-BCZ) by Polypropylene microplastic in simulated seawater was studied. Factors, including particle size, salinity and concentration, were investigated, and the experimental results were simulated using a mathematical model. Results showed that the pseudo-second-order kinetic model was more suitable to describe the sorption of polyhalogenated carbazole by microplastics, with equilibrium sorption times of 6 h and 8 h for 3,6-BCZ and 1,3,6,8-BCZ, respectively. Sorption capacity increased with decreasing particle size and the adsorption capacity increased initially and then decreased with increasing salinity, with a maximum sorption occurring at salinity of 14%. Moreover, the sorption amount increased with the increasing concentration of polyhalogenated carbazole. The sorption isotherms were confirmed as the extended Langmuir model and the extended Freundlich model, both of which were S-type.

Sorption of Tonalide, Musk Xylene, Galaxolide, and Musk Ketone by microplastics of polyethylene and polyvinyl chloride.

The effects of time, temperature, and salinity on the adsorption of Tonalide (AHTN), Musk Xylene (MX), Galaxolide (HHCB), and Musk Ketone (MK) by microplastics of polyethylene (PE) and polyvinyl chloride (PVC) are studied. Results indicate that the equilibrium sorption time was about 10 h and the adsorption kinetics model conformed to the first-order adsorption kinetic model and pseudo-second order kinetic model, this indicates that the main adsorption mechanism might be chemical adsorption and physical absorption. Adsorption reached a nadir at 15 °C and 14% salinity. The adsorption capacity gradually increases, and then decreases, finally increases with an increase in NaCl concentration. Due to the specific surface area and the pore volume of PVC was larger than PE, the adsorption capacity of PVC was higher than that of PE in the equal conditions.

Marine microplastic-associated bacterial community succession in response to geography, exposure time, and plastic type in China's coastal seawaters.

Microplastics have emerged as new pollutants in oceans. Nevertheless, information of the long-term variations in the composition of plastic-associated microbial communities in coastal waters remains limited. This study applied high-throughput sequencing to investigate the successional stages of microbial communities attached to polypropylene and polyvinyl chloride microplastics exposed for one year in the coastal seawater of China. The composition of plastisphere microbial communities varied remarkably across geographical locations and exposure times. The dominant bacteria in the plastisphere were affiliated with the Alphaproteobacteria class, particularly Rhodobacteraceae, followed by the Gammaproteobacteria class. Scanning electron microscopy analysis revealed that the microplastics showed signs of degradation. Microbial communities showed adaptations to plastisphere including more diverse microbial community and greater "xenobiotics biodegradation and metabolism" in metabolic pathway analysis. The findings elucidate the long-term changes in the community composition of microorganisms that colonize microplastics and expand the understanding of plastisphere microbial communities present in the marine environment.

The formulation and immunisation of oral poly(DL-lactide-co-glycolide) microcapsules containing a plasmid vaccine against lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus).

Nucleic acid-based immunotherapy is a new treatment option for fish immunisation in intensive culture. However, DNA-based vaccines would be hydrolyzed or denaturized because of the existence of nucleases and severe gastrointestinal conditions. Poly(DL-lactide-co-glycolide) (PLGA) microcapsules, loaded with plasmid DNA (pDNA) against lymphocystis disease virus (LCDV), were prepared by modified water in oil in water (W/O/W) double emulsion method in our laboratory. Encapsulation efficiency, loading percent and diameter of microcapsules were 78-88%, 0.5-0.7% and less than 10 mum, respectively. In simulated gastric fluid (SGF), less than 10% of pDNA was released from microcapsules in 12 h, and about 6.5% of pDNA was released in 12 h in simulated intestinal fluid (SIF). The content of the supercoiled of pDNA in microcapsules and control was 80% and 89% respectively, which indicated that a little supercoiled pDNA degradation occurred during encapsulation. RT-PCR showed that lots of RNA containing information of MCP gene existed in all tissues of fish vaccinated with microcapsules 10-90 days after oral administration. SDS-PAGE and immunoblots, as well as immunofluorescence images, displayed that major capsid protein (MCP) of LCDV was expressed in tissues of fish vaccinated with pDNA-loaded microcapsules. In addition, indirect enzyme-linked immunosorbent assay (ELISA) showed that the immune responses of sera were positive (O.D> or =0.3) from week 1 to week 24 for fish vaccinated with microcapsules, in comparison with fish vaccinated with naked pDNA. Our results suggested that PLGA microcapsules were promising oral carriers for pDNA delivery. This encapsulation technique had potential for drug delivery applications due to its ease of operation and notable immunisation efficacy.