Compared with pristine agricultural polyethylene (PE) soil films microplastics (MPs), aged agricultural polyethylene (APE) soil films MPs have a rougher surface, more cracks and have some oxygen-containing functional groups that makes them adsorb organic pollutants, such as pesticides more easily. This may be more harmful to human beings than marine MPs as the agricultural soil films are closer to our living environment. But few works focused on the adsorption of pesticides on pristine or aged agricultural polyethylene soil films MPs. In order to promote the risk assessment of co-exposure of pesticides and agricultural polyethylene soil films MPs, a comparative study on the adsorption behavior and mechanism of four pesticides (carbendazim, diflubenzuron, malathion, difenoconazole) by pristine PE MPs and APE MPs were carried out in this paper. The results showed microcracks and surface oxidation observed on APE MPs. The adsorption kinetics and isotherm models indicated that the adsorption capacity of APE MPs was higher than that of PE MPs, which attribute to the larger surface area of APE MPs. The adsorption capacities of pesticides on APE MPs were positively correlated with LogKow (Water octanol partition coefficient) values of these four pesticides, showed the hydrophobic partitioning played the most important part in the adsorption, but also some H-bonding between secondary amines in the molecular of diflubenzuron and polar O-containing functional groups on APE MPs may be formed. And electrostatic forces or interactions are not the determining factor for these pesticides adsorption behavior of PE MPs, and the effect of pH is mainly driven by changes in sorbate properties rather than changes in surface properties of MPs. The results presented herein show the APE MPs can be a better vector of most hydrophobic pesticides than pristine MPs in the agricultural field, and more attention should be paid to the problem of films and pesticides residue in farmland soil.

The aim of our study was to synthesize a pumpkin peel polysaccharide (PPP)-Cr(III) complex and investigate its hypoglycemic activity. Firstly, a novel PPP-Cr(III) complex with a Cr content of 23.77 mg/g was synthesized and characterized. Physicochemical characterization indicated that PPP-Cr(III) had some changes in chemical composition, monosaccharide composition, and morphological structure compared with PPP. The molecular weights of PPP-Cr(III) and PPP were 1.398 × 10⁶ g/mol and 3.386 × 10⁶ g/mol, respectively, showing a lower molecular weight after the introduction of Cr(III). Fourier transform infrared spectroscopy showed that a new characteristic absorption peak of Cr-O appeared at 534 cm⁻¹ in PPP-Cr(III), indicating that Cr(III) was successfully complexed with PPP. Secondly, the hypoglycemic activity of PPP-Cr(III) based on α-glucosidase inhibitory and insulin resistance (IR)-HepG2 cells was evaluated. Compared with PPP, PPP-Cr(III) exhibited a more significantly α-glucosidase inhibitory activity. The IR-HepG2 cells confirmed an obvious increase in glucose consumption. Western blot analysis demonstrated that the treated IR-HepG2 cells were able to increase the protein levels of p-AMPK and p-GSK-3β, indicating that IR-HepG2 cells exerted hypoglycemic activity via the AMPK/GSK-3β signaling pathway. These results suggested that PPP-Cr(III) had good hypoglycemic activity, which could provide theoretical support for the development of novel hypoglycemic products.