The invention described herein provides for novel nitric oxide-releasing polymers that comprise at least two adjacent units derived from acrylonitrile monomer units and containing at least one carbon-bound diazeniumdiolate. The diazeniumdiolated acrylonitrile-derived polymers can be used in medical devices therapeutically. Accordingly, the invention also provides a method of treating a biological disorder and a method of promoting angiogenesis that includes administering a medical device comprising a nitric oxide-releasing polymer comprising at least two adjacent units of acrylonitrile before exposure to nitric oxide and at least one nitric oxide releasing N2O2− group, wherein the N2O2− group is attached directly to the polyacrylonitrile backbone, to a specific location on or within the mammal in an amount effective to treat the biological disorder or promote angiogenesis.