A biasing system for the blade of a folding knife includes one component or assembly applying a force tending to move the knife blade from a closed position, nested in the handle, to an open position, extending from the handle. By providing for transcriptional initiating regulation dependent upon transcription factors that are only active in specific, limited cell types, virus replication will be restricted to the target cells. The rotating locking hub includes a locking feature that protrudes into the printing mechanism to radially lock the ribbon spool when the locking hub is in a locked position.