Study On Multi-scale Structure And Biomimetics Of Cercariae Spines Of Schistosoma Japonicum

Schistosomiasis japonica(S.japonica)is a kind of persistent disease that affects the health and economic development of Chinese people.Through years of effort from professional institutions and scientific researchers,the great achievements in effective control of schistosomiasis,and the China is recognized and admired by the world.It is necessary to strive to eliminate schistosomiasis nationwide in 2025.However,the cercariae of S.japonicum is small size,and there are few researches on the movement form of cercariae in water,the microstructure of cercariae surface and the invasion mechanism.Therefore,this contribution is used to study the movement of cercariae in water and the relationship between the multi-scale structure of cercariae and the structure-activity of penetrating skin.Moreover,further reveal the mechanism of rapid penetrating skin,and provide new ideas for bionic intelligent materials.The main research contents include:1.Multiscale structure of cercariae of S.japonicum.The cercariae escaping from Oncomelania were fixed by osmic acid/glutaraldehyde fixative,and the dehydration deformation of cercariae was prevented by gradient displacement of tert-butanol.Scanning electron microscopy(SEM)was used to observe surface structures of the cercaria samples.It was found that cercaria,like tadpole structure,can be divided into head and tail.The head of cercaria contains organs such as abdominal sucker and head organ,and the whole body of cercaria is covered with body spines.The body spines of different parts are different in size,the head body spines are shorter and smaller,and the tail is longer and slender.A systematic study of the multiscale structure of cercariae of S.japonicum lays a foundation for revealing the mechanism of cercariae penetrating the skin.2.Study on the movement of S.japonicum cercariae in water.The process of cercariae escaping from Oncomelania to water surface was observed by electron microscope and CCD camera.It is found that the cercariae head down and tail up,through the tail swing to the water surface.The statistical analysis of the swimming speed of head and tail,the result shows that the swinging speed is positively related to the swimming speed of head and tail.The driving force of upward movement is the difference of upward resistance in the process of continuous swinging and recovery of cercaria tail.To observe the process of cercaria penetrating into mouse skin,cercaria penetrates through mouse skin through head stretching and tail swinging.The expansion period of cercaria head was analyzed statistically,and the model was established to reveal the mechanism of cercaria penetrating skin rapidly,which provided a new idea for bionic intelligent interface materials.3.The construction of flexible cone array of schistosoma cercariae.Magnetic fluid was induced to produce cone-shaped structure by magnetic field.184 glue and cobalt particles were used to configure magnetic fluid.The shape of magnetic cone was adjusted by controlling the proportion of 184 glue and cobalt particles and the intensity of magnetic field,so that it was similar to the body spine of cercariae head.The resistance increasing effect of cercariae was tested and verified.