Optical tweeze-sectioning microscopy for 3D imaging and manipulation of suspended cells

Optical manipulation and detection of biological particulates are crucial procedures in biophotonics. Optical sectioning (OS) opens the avenue to three-dimensional (3D) microscopy, but nonoptical approaches, including sample adhesion and mechanical scanning, have always been required in this technique, rendering it impossible to image suspended cells. Here, we develop optical tweeze-sectioning microscopy by coupling structured illumination microscopy (SIM) with holographic optical tweezers (HOTs). By sculpting light in HOTs, we demonstrate that the position fluctuations of suspended yeast cells can be optically squeezed to tens of nanometers, which is sufficient for the implementation of OS with SIM. Sample scanning is achieved through optical delivery of the cells, instead of translation stages as in the conventional way. Our work presents an all-optical solution for OS, broadening its application to nonadherent, suspended cells. It further furnishes the original technique that enables both SIM-based 3D imaging and optical manipulation.