Single-objective lattice light sheet microscopy with microfluidics for single-molecule super-resolution imaging of mammalian cells.

Single-molecule localization microscopy (SMLM) has redefined optical imaging by enabling imaging beyond the diffraction limit, allowing nanoscale investigation into cellular architecture and molecular dynamics. Light sheet illumination enhances SMLM through optical sectioning of the sample, which drastically improves the signal-to-background ratio and reduces photobleaching and photodamage. Lattice light sheet (LLS) microscopy, in which a 2D optical lattice is implemented for light sheet illumination, can provide exceptional sectioning and extended imaging depth when imaging in scattering samples. However, its conventional dual-objective design poses challenges for certain applications. Here, we present an imaging platform which implements LLS illumination with a reflective single-objective geometry (soLLS) inside a microfluidic chip, enabling the use of a single high numerical aperture objective for both illumination and detection, mitigating constraints of a dual-objective setup. We provide quantitative characterization of the propagation properties of the soLLS and demonstrate that it outperforms conventional Gaussian light sheets in terms of useful field of view and sectioning when propagating through scattering samples. Next, by combining soLLS with point spread function engineering, we demonstrate the platform for improved 3D single-molecule super-resolution imaging of multiple targets across multiple cells. The soLLS imaging platform thus expands investigations of nanoscale cellular and intercellular structures and mechanisms into more challenging samples for a wide range of applications in biology and biomedicine.