Would it be possible to suspend these kinds of particles using a standing wave of ultrasound ? Perhaps something similar to https://www.researchgate.net/publication/265401333_Cell_and_... and then project the laser on them.
I would guess that the relatively long wavelength of ultrasound could potentially cause resolution issues.
I doubt ultrasound can provide the same fidelity as a highly-tuned laser high-frequency laser beam when it comes to keeping something in one place.