A vascular closure device can include both a mechanical component and a biological component for sealing an arteriotomy. The mechanical component reduces the size or closes the arteriotomy. The biological component covers and fills any spaces or cracks present after the arteriotomy has been mechanically reduced in size. An exemplary embodiment includes a suture or clip to approximate the edges of the arteriotomy, and a smooth rounded plug is advanced along the suture towards the closed arteriotomy. An applicator device can be used to deliver the plug and, in particular, the device can include a guidewire that is offset from a central axis along a side of the applicator. In situ, the plug transforms to a flowable or gel state and fills and covers any cracks and spaces along the closed arteriotomy.