Effects Of Cadmium Telluride Quantum Dots And Tungsten Selenide Nanodots On The Gut Microbiota

In recent years,with the wide application of nanomaterials in biomedical fields,biosafety research of nanomaterials has become increasingly important.The gastrointestinal tract,which is the most susceptible to foreign substances,plays an important role in the body’s immunity and intestinal barrier protection through the steady state regulation of gut microbiota.The research on the influence of nanomaterials on intestinal microbes has become a hot research topic.Here,the effects of two representative nanomaterials,cadmium telluride quantum dots(QDs)and tungsten selenide nanodots(nanodots),on gut microbiota were investigated.Firstly,the effects of CdTe QDs on gut microbiota were uncovered after oral and intravenous administration.Secondly,tungsten selenide nanodots were used in the regulation of the imbalanced gut microbiota disease treatment in mice with ulcerative colitis.The main content of this paper includes the following aspects:Chapter 1: The research status of nanomaterials,especially QDs and two-dimensional transition metal chalcogenides,as well as the current research results on biosafety,and summarizes the close relationship between gut microbiota and human health were introduced.Chapter 2: The effects of high and low dose of CdTe QDs on intestinal tract and intestinal microorganism of mice were studied by injection.The results indicate that different doses of CdTe QDs alter the gut microbiota in two distinct ways and have varying degrees of effects on intestinal health.Injection of low dose of CdTe QDs resulted in a large increase in the number of lactobacilli on day 1,which was reduced over time,but still caused oxidative stress in the intestine on days 5 and 15,inflammation Reaction and intestinal bleeding.High doses of CdTe QDs reduce the gut microbiota diversity and anti-inflammatory capacity of the intestinal mucosa and lead to mild intestinal damage and pathogenic bacteria.This study shows that low dose of CdTe quantum dots have no obvious toxicity and damage to vital organs such as liver,kidney,spleen and lung,but they have toxic effects on gut microbiota and intestinal tract.Chapter 3: The effects of different concentrations of CdTe QDs on lipid metabolism,major organs,intestinal immunity and intestinal microbes in mice were studied by oral gavage.The mice were orally administered with different concentrations of quantum dots for 28 days.The results showed that the low dose(less than 20 μM)QDs had less effect on the overall growth of the mice and the major organs.However,gavage of QDs lead to an increase in the abundance of gut microbiota,and the ratio of Firmicutes/Bacteroidetes(F/B)is imbalanced,resulting in an imbalance of blood lipid metabolism in mice.Oral high-dose quantum dots(200 μM)also cause liver and kidney function damage and intestinal inflammation during the imbalance of blood lipid metabolism in mice.Chapter 4: The research content of this chapter is based on the fact that tungsten can regulate the growth of anaerobic bacteria(especially E.coli)in the intestine and the antibacterial effect of tungsten selenide.Application of tungsten selenide nanodots to regulate DSS-induced imbalanced intestinal microflora in mice with ulcerative colitis to alleviate and treat ulcerative colitis in mice.The experimental results show that tungsten selenide nanodots can inhibit the growth of E.coli under anaerobic conditions in vitro.Through the SEM and the determination of nitrate reductase activity in the bacterial liquid,it is preliminarily concluded that the tungsten selenide nanodots mainly achieve the purpose of inhibiting the growth of E.coli by physically destroying and destroying the respiratory channel.The application of tungsten selenide nanodots to the treatment of DSS-induced mouse colitis showed that oral administration of tungsten selenide nanodots can effectively alleviate colon length shortening caused by colitis.By regulating the intestinal microbial homeostasis in mice and inhibiting the proliferation of facultative anaerobic bacteria in the intestine,the inflammation of the colon is alleviated.The expression in induced colitis relieves intestinal inflammation and provides a viable new method for the treatment of colitis.