| The present disclosure provides a polyproline nanocage compound, which includes two cyclic peptide scaffolds and at least three connecting molecules. Each of the two cyclic peptide scaffolds includes at least three polyproline II helix rods and at least three turn-angle molecules, and two of the at least three polyproline II helix rods are connected by one of the at least three turn-angle molecules to form a closed ring. The at least three connecting molecules are connected from each of the polyproline II helix rods of one of the two cyclic peptide scaffolds to each of the polyproline II helix rods of another of the two cyclic peptide scaffolds. Accordingly, the polyproline nanocage compound of the present disclosure is biocompatible, and the connection position and the number of the functional groups can be controlled, which is suitable for the various applications. |