A polycation capable of forming a complex with a nucleic acid for carriage thereof. The polycation comprising at least one cyclic compound having a cavity. A polymer backbone is threaded into the cavity of the cyclic compound. A pair of bulky moieties cap the terminals of the polymer backbone to inhibit dethreading of the cyclic compound from the polymer backbone. In use, the net positive charge of said polycation enables a complex to form with nucleic acid.