: Cellulose is the most abundant biopolymer on
Earth. Cellulose fibers, such as the one extracted form cotton
or woodpulp, have been used by humankind for hundreds of
years to make textiles and paper. Here we show how, by
engineering light−matter interaction, we can optimize light
scattering using exclusively cellulose nanocrystals. The
produced material is sustainable, biocompatible, and when
compared to ordinary microfiber-based paper, it shows
enhanced scattering strength (×4), yielding a transport mean
free path as low as 3.5 μm in the visible light range. The
experimental results are in a good agreement with the
theoretical predictions obtained with a diffusive model for light propagation.