Volumetric and Optofluidic Live-cell Imaging Using High-Resolution Fourier Light-Field Microscopy (HR-FLFM)

Intracellular organelles in live cells have played a significant role in the spatiotemporal regulation and processes of cellular systems. The visualization of submicron-scale organelle structures and dynamics inside cells requires high-resolution highthroughput microscopic techniques, together with 3D multicolor live imaging capabilities. Light-field microscopy (LFM), which rapidly emerged in recent years as a scanning-free and scalable imaging method, has been widely used for observing structural and functional information spanning many spatiotemporal scales from single cells to mammalian brains. Recent developments of Fourier light-field microscopy (FLFM) have further improved image quality and enhanced computational efficiency by capturing the 4D light field in the Fourier domain. Unlike previous works, which primarily focus on largescale tissues and fixed biological samples, here, we report a high-resolution FLFM (HR-FLFM) to broaden its applications to the realm of high-resolution volumetric and optofluidic imaging for live cells. In HR-FLFM, we have designed a hexagonal microlens array (MLA) to achieve uncompromised subcellular visualization. A 3D deconvolution algorithm using a hybrid PSF has been innovatively developed to reduce the reconstruction artifacts and upgrade the performance of the system. We have demonstrated the 3D optofluidic imaging capabilities of HR-FLFM on typical biological models such as mitochondria and peroxisomes in both fixed and live cells, and the integration with microfluidic systems to achieve a high imaging throughput of the system. We anticipate that HR-FLFM will provide a multiplexed methodology for investigating subcellular anatomy, functions and cell-to-cell variability, paving a promising pathway for broad single-cell investigations and technological breakthroughs.