A method of introducing biological material into cells includes providing one or more target cells and establishing a spray of substantially dispersed particles including biological material. The substantially dispersed particles have an electrical charge applied thereto such that one or more of the substantially dispersed particles of the spray is introduced into one or more of the target cells. The spray of substantially dispersed particles may be established by dispensing a spray of microdroplets suspending particles. The electrical charge is concentrated on the suspended particles as the microdroplet evaporates. The suspended particles may include carrier particles with biological material or the suspended particles may be particles of biological material alone. The space charge effect of the concentrated electrical charge on the substantially dispersed particles of the spray enable one or more of the particles to be introduced into one or more of the target cells.