A simple method for manufacturing biological nano-aerosols is described. It is based on gas-phase neutralization of a cloud of highly charged electrospray-generated particles or macromolecular ions with a cloud of oppositely charged electrospray products, e.g., ions of a volatile solvent. It was demonstrated that the electrosprayed products became neutralized within a few seconds, forming a stable nano-aerosol composed of single polymer molecules, nanofibers, or nano-clusters of different sizes, depending on polymer concentration, solvent, humidity, and other factors. It was also demonstrated that enzymes aerosolized by this mild technique retain their specific activity, which opens a variety of new applications for this technology. (C) 2011 Elsevier Ltd. All rights reserved.