Disclosed are inclusion complexes suitable for use as histotripsy agents, the methods used in the preparation of the inclusion complexes, and the use of the complexes as histotripsy agents or for drug delivery.

A metal composite for ultrasonic contrast. The metal composite has a metal nano-structure and comprises a contrast core and a shell ligand coated on the contrast core. The contrast core includes metal ions, and the shell ligand includes a polymer having a chelating group, wherein the chelating group is a Lewis base which forms a coordination covalent bond with the metal ions to form a stable metal nano-structure; and the metal ions can effectively generate echoes of ultrasonic waves, enhance the brightness and contrast of the image, and help stabilize the metal nano-structure in the form of Lewis acid-base pair chelation, so that the metal ions will not easily disintegrate during circulation in the human body, thereby meeting the needs of long-time contrast imaging.