<p>2D materials, including Ti₃C₂ MXene, have gained significant attention in biomedical and photocatalytic applications due to their unique physicochemical properties, including a layered structure, tunable surface chemistry, and environmental responsiveness. Although significant progress has been made in synthesis and performance evaluation, the impact of nanostructure organization under realistic conditions has not been sufficiently investigated. Traditional surface-sensitive techniques are limited in their ability to probe MXene systems under wet and physiological conditions. Small-angle neutron scattering is a non-destructive, bulk-sensitive technique for studying MXene dispersions. This review emphasizes recent advances, focusing on the quantitative analysis of nanosheet dimensions, interlayer spacing, aggregation behavior, porosity, and dynamic structural evolution. These parameters have a significant impact on charge transport, catalytic activity, drug-loading capacity, and biocompatibility. Nanostructure organization and functional performance are strongly correlated. Small-angle neutron scattering is a powerful tool in elucidating the structure–property relationship and guiding the rational design of MXene-based technologies.</p> Graphical abstract <p>Comprehensive schematic illustration of Ti₃C₂ MXene-mediated photocatalytic electron transfer during light exposure and its versatile biomedical use.</p> <p></p>