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Behaviour of zinc oxide nanoparticles in the human digestive system

Project


Project code: BfR-LMS-08-1322-676
Contract period: 01.01.2017 - 31.12.2017
Purpose of research: Applied research

Zinc is known as a micronutrient and therefore used in many dietary supplements. Furthermore, zinc oxide has an antibacterial effect and is therefore of interest as a nanomaterial. High doses of zinc oxide cause liver and kidney failure in animal experiments. The Scientific Committee on Food (SCF) recommended an upper limit of zinc intake of 25 mg/ person per day. Nevertheless, it is still unknown how zinc oxide nanoparticles behave in the human digestive tract with regard to their physicochemical properties and whether these particles exert altered toxicity. Zinc oxides show an increased ion release in acidic environment. Therefore, dissolution of zinc oxide nanoparticles in the stomach due to the acidic pH is assumed and has been demonstrated using a very simple in vitro gastric juice simulation fluid. Unfortunately, this model just contained pepsin at a pH of 2. Possible particle-stabilizing effects of other components like proteins, mucines or food ingredients was ignored. Especially for silver nanoparticles, it has been shown that these nanoparticles disappear in gastric juice due to ion release and particle agglomeration but reappear in the same size range when intestinal juice is added. Therefore, silver nanoparticles reach and come in contact with intestinal cells in their nanoparticulate form. This type of particle reappearance or de novo formation has not been yet investigated for zinc oxide. It is thus not known whether zinc oxide nanoparticles reach the intestinal cells as totally dissolved ions or as particles. This project focuses on the influence of particle properties such as size and coating, as well as on the influence of the composition of digestion fluids and food ingredients on ion release and particle agglomeration of zinc oxide nanoparticles in the human digestive tract.

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Subjects

Framework programme

BMEL - research cluster

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