Magnetofection of primary motor neurons is highly efficient. Primary motor neurons (2 DIV) were transfected with pmaxGFP using magnetic nanobeads. Different amounts of DNA and beads and different media were tested to optimize transfection efficiency. Cells were fixed 2 days post transfection and stained using neurofilament (NF) and HB9 antibodies to identify motor neurons. A. Representative image of a motor neuron culture from an entire 15 mm diameter coverslip. B. GFP/HB9+ cells were scored and normalized to the number of HB9+ cells. Maximum efficiency of transfection (46%) was achieved using 0.5 μg DNA and 1.75 μl beads (mean and SEM, n = 3). C. Neurobasal medium inhibited motor neuron transfection when used during DNA/beads complex formation. MEM is shown as a positive control. Size bars: 1 mm in A, 50 μm in B.