UC Irvine

Microscopy is a fundamental tool in scientific research, allowing the visualization ofstructures not visible to the naked eye. However, imaging thick tissue samples presents challenges due to light scattering from mismatched refractive indices. Tissue clearing techniques solve these issues by rendering tissues transparent, enhancing image quality and contrast-to-background ratios. Despite benefits, common methods can result in tissue deformation, long processing times, and fluorescence quenching. To address these issues, two advanced techniques have been developed: immunolabeling-enabled solvent-cleared organs (iDISCO) and the Fast Optical Clearing Method (FOCM). iDISCO is highly effective in large-scale tissue clearing, ideal for comprehensive studies, but uses hazardous chemicals and requires days to clear tissues. In contrast, FOCM offers a safer, more rapid alternative, achieving tissue transparency in as little as five minutes while maintaining vessel intensity and preserving fluorescence. This study aims to compare the efficacy of FOCM to iDISCO in enhancing imaging quality, focusing on vessel intensity and contrast-to-background ratios in one-millimeter-thick mouse brain samples. By comparing one-millimeter-thick mouse brain samples, the study found that FOCM maintained vessel intensity and contrast-tobackground ratios comparable to iDISCO. FOCM was also tested at 5, 60, and 48 hours, demonstrating increased vessel intensity and contrast over time, with 48 hours providing optimal results. This makes FOCM particularly useful for time-sensitive analyses while maintaining image quality