A dual channel spray gun, and method of use thereof, for fabricating nanostructures including a pharmaceutical/therapeutic agent having enhanced oral bioavailability. The nanostructures are a mixture of at least two (2) solutions/media substantially equally distributed as desired. The spray gun device uses gas pressure and/or two ultrasonicators to simultaneously prepare two solution systems for subsequent mixture and atomization. The gas pressure and frequencies of the ultrasonicators are adjustable for each channel of the spray gun. In operation, the spray gun is used to prepare microstructures that, for example, contain at least one active pharmaceutical agent in one solution system and excipients, such as coating or bioadhesives, in the other solution system. Any combination of solution systems is contemplated, such as both systems containing a pharmaceutical agent or both systems containing excipients.