Ultramicro-volume syringes were fabricated by integrating micro-nanostructure arrays in microchannels for quantitatively dispensing sub-picoliter volumes of liquids. Using this system, liquids were dispensed in volume increments as low as 0.5 pL with 96% accuracy. Specifically, the controllable synthesis of nanocrystals was achieved using a lab-on-chip platform that was integrated with the syringes.