Introduction: Studies have shown that microplastics (MPs) and nanoplastics (NPs) could accumulate in the human body and pose a potential threat to human health. The purpose of this study is to evaluate the biodistribution and toxicity of MPs/NPs with different particle sizes comprehensively and thoroughly. Methods: The purpose of this study was to investigate the biodistribution and in vivo toxicity of polystyrene (PS) MPs/NPs with different sizes (50 nm, 100 nm, and 500 nm). The BALB/c mice were given 100 μL of PS50, PS100 and PS500 at the dosage of 1 mg/kg BW or 10 mg/kg BW, respectively, by gavage once a day. After 28 consecutive days of treatment, the biodistribution of differently sized PS MPs/NPs was determined through cryosection fluorescence microscopy and fluorescent microplate reader analysis, and the subsequent effects of differently sized PS MPs/NPs on histopathology, hematology and blood biochemistry were also evaluated. Results: The results showed that the three different sizes of PS MPs/NPs were distributed in the organs of mice, mainly in the liver, spleen, and intestine. At the same time, the smaller the particle size, the more they accumulate in the body and more easily penetrate the tissue. During the whole observation period, no abnormal behavior and weight change were observed. The results of H&E staining showed that no severe histopathological abnormalities were observed in the main organs in the low-dose exposure group, while. Exposure of three sizes of PS MPs/NPs could cause some changes in hematological parameters or biochemical parameters related to heart, liver, and kidney function; meanwhile, there were size- and dose-dependencies. Conclusion: The biological distribution and toxicity of plastic particles in mice were more obvious with the decrease of particle size and the increase of concentration of plastic particles. Compared with MPs, NPs were easier to enter the tissues and produce changes in liver, kidney, and heart functions. Therefore, more attention should be paid to the toxicity of NPs.

Obesity is one of the risk factors of metabolic diseases. Decreased sensitivity to insulin or impairment of the insulin signaling pathway may affect the metabolism of adipose tissue. Bisphenol F (BPF) has been widely used in various products as a substitute for bisphenol A (BPA). BPA has been defined as "obesogen". However, knowledge about the correlation between BPF and obesity is very limited. This study was aimed to explore the effects of BPF on glucose metabolism and insulin sensitivity in mammalian tissues, using a mouse 3T3-L1 adipocyte line as the model. Differentiated 3T3-L1 adipocytes were treated with BPF at various concentrations for 24 h or 48 h, followed by the measurement of cell viability, lipid accumulation, expression levels of adipocytokines, glucose consumption, and impairment of the insulin signaling pathway. The results indicated that BPF had no effect on the size of 3T3-L1 adipocytes, but the expression of leptin, adiponectin and apelin was decreased, while that of chemerin and resistin was increased after 48 h of BPF treatment. Moreover, BPF inhibited the glucose consumption, the expression of GLUT4, and its translocation to the plasma membranes in 3T3-L1 adipocytes. Western blot analysis indicated that the activation of IRS-1/PI3K/AKT signaling pathway was inhibited by BPF, which resulted in reduced GLUT4 translocation. In conclusion, our data suggest that exposure of adipocytes to BPF may alter the expression of calorie metabolism-related adipokines and suppress insulin-stimulated glucose metabolism by impairing the insulin signaling (IRS-1/PI3K/AKT) pathway.

Quercetin is a well-known flavonoid for its potent antitumor and antiproliferative effects on a wide range of human cancer cell lines. However, the delivery of quercetin is challenging due to its extreme insolubility in water. The intention of this study was to evaluate the antitumor effect of quercetin-loaded PEGylated liposomes (PEG-Que-NLs) in vitro and in vivo. We first prepared PEG-Que-NLs by method of thin film hydration; further determined, the optimum ratios of quercetin to Soybean phosphatidylcholine (SPC), to cholesterol (CHL), and to PEG-4000 were 1 : 8, 1 : 2, and 1 : 2 ( ), respectively, and the optimal hydration temperature was 55°C when the mean vesicle diameter and apparent Zeta potential of PEG-Que-NLs were found to be nm and mV, respectively; the encapsulation efficiency and the drug loading of PEG-Que-NLs were and , respectively. Drug release study in vitro showed that PEG-Que-NLs exhibited a slow-release effect without significant burst effect. Furthermore, the inhibition effect of PEG-Que-NLs on HeLa cells was considerably higher than free quercetin (free-Que) and quercetin liposomes (Que-NLs). Intravenous injection of PEG-Que-NLs into U14 bearing mouse models inhibited the cervical carcinoma growth significantly, and the tumor inhibition rate was much higher than free-Que and Que-NLs. These results of this study indicated that PEG-Que-NLs exhibited potential application prospects in the treatment of malignant tumors because of its tumor targeting, slow-release properties, and the solubility improvement of quercetin.