Provided is a method of delivering a medicament or a diagnostic agent to a subject in need thereof by (a) introducing a microtube configured to deliver the medicament or the diagnostic agent into the subject, said microtube comprises an electrospun shell and an electrospun coat over an internal surface of said shell, and (b) administering the medicament or the diagnostic agent through said microtube, thereby delivering the medicament or the diagnostic agent to the subject. Also provided are kits for delivering a medicament or a diagnostic agent.