Biofabrication of a ring-shaped construct from tissue spheroids in a magnetoacoustic field

А new method for the biofabrication of tissue engineering constructs from tissue spheroids was proposed, based on the manipulation of spheroids using magnetic and acoustic radiation forces. Unlike most modern methods that use scaffolds to shape the structure, the proposed method fabricates levitating spheroids. The levitation effect is achieved due to the strong magnetic field gradient and the difference in the paramagnetic susceptibilities of the spheroids and the solution in which they are located. The structure was formed in an area where gravity was compensated by magnetic forces in the vertical direction, and due to the magnetic gradient in the horizontal plane, the tissue spheroids moved towards each other, rising above the bottom of the container. In turn, the acoustic field formed the structure of the assembled tissue-engineering structure. One of the most desirable forms is a ring or tube, since it is precisely this form that vessels in human tissues have. This shape was fabricated using a cylindrical piezoelectric transducer, which created a standing cylindrical ultrasonic field. The acoustic radiation force acted from the antinode to the node, forming a ring of tissue spheroids. Holding spheroids in such a trap for 18–20 hours led to their fusion into continuous living tissue in the form of a ring. Changing the frequency and amplitude of the ultrasonic wave made it possible to regulate the diameter and thickness of the conglomerate of spheroids.