There is disclosed an apparatus for providing an ionized analyte for mass analysis by photon desorption comprising at least one layer for contacting an analyte, and a substrate on which said layer is deposited. Also included are sterol-modified hedgehog polypeptides and functional fragments thereof. A valve is located between the drainage portion and the venting portion. The fibers of the invention are useful in a variety of applications. An inflatable membrane configured on the balloon catheter is used to firmly implant the attachment systems within the vessel.