Methods and compositions are provided for generating and applying long-lasting therapeutic nitric oxide (NO) gas from the reaction of a least one microencapsulated nitrite salt and an activating volume of an aqueous acidified gel that has sufficient acidity to convert the nitrite salt to a nitric oxide (NO) and further provides a reducing property that retains the NO in bioactive form.本發明係揭露一種透過至少一種微囊化的亞硝酸鹽和激活體積的水凝膠之反應、長時間持續產生和應用治療性一氧化氮氣體的組合物和方法,所述之水凝膠具有足夠的酸度將亞硝酸鹽轉化為一氧化氮,還具有保持一氧化氮生物活性的還原性質。