Recent advances in understanding the effects of nanomaterials on gut microbiota

The gut microbiota is a large symbiotic microorganism community located in the human digestive tract. It plays a profound role in human health by modulating multiple life functions, such as immune development, metabolism regulation, and nutrient absorption. Alterations in the gut microbiota may influence the host health. Recently, the wide application of nanomaterials in every aspect of human life has increased the opportunity of exposure of gut microbiota to nanomaterials, which has led to public concern regarding the consequence of contact between nanomaterials and the gut microbiota. Herein, we attempt to provide a comprehensive summary of recent advances and theories regarding occurrence mechanisms in this field of study. In this work, we first utilize the Web of Science (WOS) innate function and bibliometric methods to identify annual publication trends, the most popular nanomaterials, and popular topics of research interests in this field. Related studies on nanomaterialmediated gut microbiota alterations and their bio-effects are summarized. More importantly, the possible occurrence mechanisms of the effects, based on the physicochemical properties of nanomaterials, are discussed. Finally, the existing challenges and future development directions are proposed. It is hoped that such a review will be helpful in identifying current research trends, providing an in-depth understanding of biological effects, and further promoting the development of this important field.