Although the risks of microplastics in environmental exposure and human health are being increasingly studied, little is known about the behavior of "eco-friendly" bioplastics in humans, especially their effects on our gastrointestinal tract. Here we demonstrate that enzymatic hydrolysis of bio-based polylactic acid (PLA) microplastics rapidly generates an excess of nanoplastic particles by competing for triglyceridedegrading lipase during gastrointestinal processes. These tiny nanoparticles are oligomers formed by hydrophobic-driven self-aggregation, and upon exposure the oligomers and their associated nanoparticles can bioaccumulate in in vitro and several in vivo organs, including the liver, intestine, and even in the brain. Severe intestinal damage and in ammation are also observed, the toxic effect of which is mostly pronounced from hydrolyzed oligomer products. Furthermore, the oligomers' potential protein target screening using large scale pharmacophore model reveals that oligomers can interact with matrix metallopeptidase 12 protein (MMP12), which is further validated using protein binding assay. A close mechanistic study reveals high binding a nity of oligomers to the catalytic zinc ion nger domain, leading to MMP12 inactivation and mediating the adverse bowel in ammatory effect following PLA oligomer exposure. Since biodegradable plastics are highly proposed as one solution for the global plastic problem, understanding the gastrointestinal fate and toxicity of bioplastics, will provide groundbreaking data on bioplastics as a substantial risk to human health.

Our previous research work indicated that highly boron doped polysilicon nanofilms (≤100 nm in thickness) have higher gauge factor (the maximum is ∼34 for 80 nm-thick films) and better temperature stability than common polysilicon films (≥ 200nm in thickness) at the same doping levels. Therefore, in order to further analyze the influence of deposition temperature on the film structure and piezoresistance performance, the piezoresistive sensitivity, piezoresistive linearity (PRL) and resistance time drift (RTD) of 80 nm-thick highly boron doped polysilicon nanofilms (PSNFs) with different deposition temperatures were studied here. The tunneling piezoresistive model was established to explain the relationship between the measured gauge factors (GFs) and deposition temperature. It was seen that the piezoresistance coefficient (PRC) of composite grain boundaries is higher than that of grains and the magnitude of GF is dependent on the resistivity of grain boundary (GB) barriers and the weight of the resistivity of composite GBs in the film resistivity. In the investigations on PRL and RTD, the interstitial-vacancy (IV) model was established to model GBs as the accumulation of IV pairs. And the recrystallization of metastable IV pairs caused by material deformation or current excitation is considered as the prime reason for piezoresistive nonlinearity (PRNL) and RTD. Finally, the optimal deposition temperature for the improvement of film performance and reliability is about 620 °C and the high temperature annealing is not very effective in improving the piezoresistive performance of PSNFs deposited at lower temperatures.

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