No abstract

Indirect evidence has determined the possibility that microplastics (MP) induce constipation, although direct scientific proof for constipation induction in animals remains unclear. To investigate whether oral administration of polystyrene (PS)-MP causes constipation, an alteration in the constipation parameters and mechanisms was analyzed in ICR mice, treated with 0.5 μm PS-MP for 2 weeks. Significant alterations in water consumption, stool weight, stool water contents, and stool morphology were detected in MP treated ICR mice, as compared to Vehicle treated group. Also, the gastrointestinal (GI) motility and intestinal length were decreased, while the histopathological structure and cytological structure of the mid colon were remarkably altered in treated mice. Mice exposed to MP also showed a significant decrease in the GI hormone concentration, muscarinic acetylcholine receptors (mAChRs) expression, and their downstream signaling pathway. Subsequent to MP treatment, concentrations of chloride ion and expressions of its channel (CFTR and CIC-2) were decreased, whereas expressions of aquaporin (AQP)3 and 8 for water transportation were downregulated by activation of the mitogen-activated protein kinase (MAPK)/nuclear factor (NF)-κB signaling pathway. These results are the first to suggest that oral administration of PS-MP induces chronic constipation through the dysregulation of GI motility, mucin secretion, and chloride ion and water transportation in the mid colon.

Metal–phenolic coordinate bonds are newly used for coagulation of microplastics, reaching over 90% of removal efficiency within 5 min. The purified water using the coagulation method reduced oxidative stress and inflammatory cytokines in vitro.

The pH-dependent complexation behaviors of natural and counterionic polyelectrolyte complexes (PECs) without crosslinkers have been rarely studied. In this work, alginate (0.5-2.5 wt %) and chitosan (0.5-2 wt %) were combined to formulate turbid gel-like assemblies. The PEC was consisted of~100-μm-sized porous structure observed by scanning electron microscope images and electrostatic interactions inside the complex were newly formed characterized by Fourier transform infrared spectra. Based on visual monitoring and ultraviolet-visible absorption measurement, the complex maintained the gel-like structure under acidic, while the complex was more dissolved under becoming basic. As a demonstration of potential pH-dependent delivery, distinct release profiles of the complexes encapsulating rhodamine 6G (R6G) or doxorubicin, were observed when they were immersed in acidic, neutral, and basic medium. Within 2 h, 7.4, 35.4, and 73.7% of R6G were released under acidic, neutral, and basic condition, respectively, with reasons of degree of protonation or deprotonation of each natural polyelectrolyte at certain pH.