A nanotweezer comprises a first metastructure including a first substrate, a first electrode, and a plurality of plasmonic nanostructures; a second metastructure including a second substrate and a second electrode, wherein the second substrate and the second electrode are substantially transparent to light within a wavelength range; a microfluidic channel between the first metastructure and the second metastructure; a voltage source configured to selectively apply an electric field between the first electrode and the second electrode a light source configured to selectively apply an excitation light to the microfluidic channel, the excitation light having a wavelength within the wavelength range. In response to the selective application of the electric field and/or the excitation light, nanoparticles within the microfluidic channel are manipulated.