A key component of nanoengineering is the controlled accumulation and delivery of nanoparticles (NPs), which is crucial for targeted therapy or the elimination of microorganisms. The method for accumulating, delivering, and releasing nanoparticles across two optical nanofibers with counter-propagating evanescent waves of 980-nm wavelength (NF). We experimentally and theoretically demonstrate that the NPs delivered along the NF surface in opposite directions are accumulated into the region where the scattering loss of the NPs ismaximum, and about 90% of the incident optical field from both ends of the NF can be coupled into the region using a 713-nmdiameter polystyrene NPs suspension and an 890-nm-diameter NF as an example. By adjusting the incident optical field, the accumulation region can be adjusted. NPs can be delivered while the two counter-propagating laser beams have a high-power ratio and then by shutting off the two lasers, discharged into the precise spots
