A drug-delivering medical device for delivering a drug to a target site in a body lumen is disclosed. The drug-delivering medical device includes a balloon catheter and an inflatable balloon positioned on the balloon catheter. The inflatable balloon has a hydrophilic surface. One or more portions of the hydrophilic surface are coated with two or more nano-carriers. A nano-carrier of the two or more nano-carriers includes a drug surrounded by an encapsulating medium. As the drug is surrounded by the encapsulating medium, the surface of the nano-carrier is devoid of the drug. When the inflatable balloon is inflated upon coming in proximity to a target site in the body lumen, about 30% to 80% of the two or more nano-carriers are released from the hydrophilic surface within 15-90 seconds.