The ability to preserve and deliver reagents remains an obstacle for the successful deployment of self-contained diagnostic microdevices. In this study we investigated the ability of bacteriophage T7 to be encapsulated and preserved in water soluble nanofibers. The bacteriophage T7 was added to mixtures of polyvinylpyrrolidone and water and electrospun onto a grounded plate. Trehalose and magnesium salts were added to the mixtures to determine their effect on the infectivity of the bacteriophage following electrospinning and during storage. The loss of T7 infectivity was determined immediately following electrospinning and during storage using agar overlay plating and plaque counting. The results indicate that the addition of magnesium salts protects the bacteriophage during the relatively violent and high voltage electrospinning process, but is not as effective as a protectant during storage of the dried T7. Conversely, the addition of trehalose into the electrospinning mix has little effect on the electrospinning, but a more significant role as a protectant during storage.