Alternative methods for the pilot-scale production and characterization of chitosan nanoparticles.

This work describes the production/characterization of low molar mass chitosan nanoparticles derived from waste shrimp shells (SSC), as well as from a commercial chitosan (CC). The production of low molar mass nanochitosan employed thermal shock, alternating between 100 °C and ambient temperature, followed by grinding the dry material (SSC and CC) in a ball mill, producing around 500 g of nanochitosan per batch. A highlight of the methodology employed is that it enables nanochitosan to be obtained even from a low quality commercial raw material. All particles had diameters smaller than 223 nm, with an average diameter below 25 nm (determined by DLS), while reductions of molar mass were between 8.4-fold and 13.5-fold. The depolymerization process resulted in a reduction in crystallinity of 38.1 to 25.4% and 55.6 to 25.9% in the CC and SSC samples, respectively. The production of nanochitosans was also confirmed by TEM through the observation of crystalline domains with diameters between 5 and 10 nm. This work perfectly reproduces the results on bench scale from previous research. The simple and inexpensive processes enable easy scale-up, representing an important advance in the production chain of biopolymers. Graphical abstract.