Chitin nanocrystals from deep-sea shrimp (Plesionika martia): Structural, morphological, and functional characterization.

Chitin nanocrystals (ChNCs) were isolated from α-chitin extracted from the underutilized deep-sea shrimp Plesionika martia via controlled acid hydrolysis, providing one of the first systematic characterizations of ChNCs derived from a deep-sea crustacean source. The structural, morphological, optical, and rheological properties of the resulting ChNCs were evaluated and compared with native chitin to elucidate the effects of nanoscale processing. The extracted ChNCs showed a yield of 62.33 ± 9.60%, a degree of deacetylation of 65.45%, and a high crystallinity index of 82.19%, indicating effective removal of amorphous domains. Transmission electron microscopy revealed rod-like nanocrystals with average dimensions of 203 ± 99 nm in length and 31 ± 16 nm in width, while dynamic light scattering confirmed a narrow size distribution (~ 200.2 nm) and high colloidal stability supported by a positive zeta potential of + 45.8 mV. UV–visible spectroscopy demonstrated enhanced optical transmittance of ChNC suspensions relative to native chitin, consistent with reduced light scattering at the nanoscale. Rheological analysis further showed that ChNC suspensions exhibited markedly lower apparent viscosity and more gradual viscosity increases with concentration compared to native chitin, reflecting reduced aggregation and improved flow behavior. These findings highlight distinct physicochemical and rheological advantages of ChNCs derived from Plesionika martia and demonstrate the potential of deep-sea shrimp shell waste as a sustainable source of high-value chitin nanomaterials for applications where optical clarity, colloidal stability, and controlled flow properties are required.