Flexible Structural Color Substrates And Their Heart-on-chips Construction

Heart is one of the most important organs of the human body,which pumps blood flow to systemic tissues for nutrients supply and normal cell metabolism.When lesions occur in the heart,it would result in damage to tissues and organs and even death.Heart disease has become the leading cause of human death worldwide,and the situation is increasingly serious.Currently,the main challenge of the drug development for heart disease is the lack of effective preclinical models of heart in vitro.Traditional planar cell culture and animal models fail to precisely predict the real human physiological environment and functions.Therefore,heart-on-a-chip has emerged to match the requirements of effective extracorporeal heart models.Heart-on-a-chip is a typical organ platform that integrates with biochemical,physical,and other factors through microfluidics.It aims to simulate the biological environment for cell culture and tissue construction,and thus achieves the physiological similarity of intracorporal cardiac tissue in vitro for drug screening,disease modeling and biological mechanism researches.Structural color,which is derived from the interaction between periodic nanostructure and incident light,exists widely in natural creatures and plays an important role in information communication and camouflage.Due to the vivid and stable color and optical property,structure color and its inherent structure have been widely studied.The structural color hydrogel is a typical example.Various structural color hydrogels with different electrical,thermal,and optical responsive properties can be obtained by selecting and compositing functional monomers,which have been employed in optical elements,detection,sensing and wearable devices.In this paper,flexible structural color substrates are used as the sensing element,and participate in the construction of visualizable heart-ona-chip based on their optical properties.The specific research contents are as follows:(1)The naturally derived soft structural color substrates were obtained by manipulating the Morpho Menelaus wing,a natural structural color material,with plasma grafting,carbon nanotubes filling,and methacrylated gelatin(Gel MA)hydrogel coating.(2)The monodispersed silica nanoparticles derived soft structural color substrates were fabricated by developing the reduced graphene oxide(r GO)composited stripe inverse opal structural color hydrogel,the photo-controlled healing structural color hydrogel,carbon nanotube sheet(CNTs)composited non-close-packed structural color hydrogel,and the heterogeneous structural color microfibers.(3)Constructing different kinds of heart-on-a-chip platforms by employing the aforementioned soft structural color substrates.Taking advantage of the surface structure of these substrates,the induced orientation of cultured cardiomyocytes was achieved,which could enhance the consistency of contraction.The dynamic visualizable sensing of the cardiomyocytes was based on the intrinsic optical properties of these substrates.(4)Implementing drug evaluation through the resultant heart-on-a-chip platforms.By pumping drug candidate solution with a certain concentration into the chip,the changes of cardiac beating frequency and contraction could be simply reflected through the change of optical signals,which demonstrated the application potentials of the heart-on-a-chip in drug screening and evaluation.The r GO doped structural color hydrogels showed a positive effect on the cardiac differentiation of human-induced pluripotent stem cells.In addition,by adjusting the size of sensing elements,single-cell level detection could be achieved,which implied a new chapter of individualized medical strategy.